HomeMy WebLinkAboutItem 5a. Study Session on the Urban Forestry Program Item 5a
Department: Public Works
Cost Center: 5004
For Agenda of: 1/11/2023
Placement: Study Session
Estimated Time: 60 Minutes
FROM: Matt Horn, Public Works Director
Prepared By: Greg Cruce, Deputy Director – Maintenance Operations
SUBJECT: URBAN FORESTRY PROGRAM STUDY SESSION
RECOMMENDATION
1. Receive a presentation on the current state of the Urban Forestry Services Program; and
2. Provide comments and direction to staff to guide the final Community Forest Plan and
implementation of a work plan in the 2023-25 Financial Plan and beyond.
POLICY CONTEXT
During the 2021-23 budget setting process, the City Council set four Major City Goals,
which included the goal of Climate Action, Open Space & Sustainable Transportation.
The Urban Forestry Services Program is instrumental in achieving this goal through the
proper management and growth of the City’s urban forest.
REPORT-IN-BRIEF
In 2001, the Public Works Department embarked on a series of assessments with a goal
of improving the City’s Urban Forest Services (UFS) Program. Through these
assessments, it was clear the community’s vision of the ideal urban forest is one where
streets are planted with appropriate trees at the appropriate spacing. The urban forest
features species and age diversification that aligns with best practices. Tree maintenance
is provided at the appropriate interval to reduce failures. When trees fail or need to be
removed, the goal is to replace with the appropriate tree in the appropriate location.
Infrastructure is appropriate to support the adjacent trees. Parks are lined with trees in
the correct locations that allow for shade, relaxation, and recreation activities. Open
spaces are planted and maintained with numerous trees providing enhanced habitat and
ecosystem functions. The tree canopy is increased and meets community
priorities. Development occurs and when it does, trees are considered, and impacts
mitigated.
The purpose of this study session is to invite comments, questions, and general input on
the Urban Forest Services Program as it relates to the various assessments and as staff
finalize the Community Forest Plan and prepare the 2023 -25 Financial Plan.
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Consistent with the Climate Action, Open Space & Sustainable Transportation Major City
Goal, the City has completed multiple assessments to guide the future management of
the City’s Urban Forest Services Program. Included with this report are four technical
studies that provide a foundation for this study session on the City’s urban forest. Studies
are as follows:
1. Attachment A is an assessment of the Urban Forest Services (UFS) Program’s
organizational structure. The report was prepared by Davey Resource Group and
includes an analysis of the staffing structure and provides recommendations which
are included in this report.
2. Attachment B is a Tree Inventory Overview Report prepared by West Cost Arborist
and is an inventory of the trees managed the UFS Program.
3. Attachment C is the Community Forest Plan which was prepared by a Cal Poly
graduate student and provides a high-level overview of the complete urban forest
and provides recommendations to meet the City’s climate action and climate
adaptation goals. This academic report serves as the basis of the forthcoming
Community Forest Plan which is currently planned to be presented to Council in
March 2023.
4. Attachment D is a Maintenance Work Plan which provides an ideal pruning and
planting plan for the assets that makeup the City’s urban forest. This report
includes specific maintenance cycles for different types of trees in the urban forest
as some species of trees require different maintenance needs.
This report provides an overview of the Urban Forest Services Program, completed
assessments, and proposed future resources to increase the level of attention to the
urban forest that is in alignment with community expectations. At this Study Session,
Council will receive a summary presentation and likely hear public input from the
community and provide feedback that will guide the growth of the City’s Urban Forest
Services Program and provide strategies to strengthen the City’s urban forest. This
feedback will be used to guide staff resource requests in the upcoming 2023 -25 Financial
Plan. To facilitate Council and Community feedback, below are a series of questions that
can be used to guide the discussion.
1. Is Council supportive of the Climate Action Plan’s vision for the majority of new “10
Tall” tree plantings primarily occurring in City Open Space?
2. Is Council supportive of a tree give-away or grant program for City residents to
plant trees on their property, which may be used to help achieve the 10 Tall
initiative?
3. Is Council supportive of a bifurcated Urban Forest Services work program across
multiple City Departments?
4. What is Council’s preferred direction on continuing the Commemorative Grove
Tree Program?
5. What size program does the Council feel is appropriate?
6. Recommendations of program phasing – align with full implementation by 2035 or
provide a quicker increase based upon available resources?
7. Would Council like a work program item to further evaluate the Tree Ordinance as
it relates to the compensatory planting pursuant to tree removals after input and
guidance from the development community and Tree Committee?
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DISCUSSION
Background
The City’s urban forest is a living and dynamic resource that offers many environmental,
social, place making, and economic benefits. Increasing the number of trees within the
City’s urban forest will be critical in combating climate change, which aligns with the City’s
2021-23 Major City Goal of Climate Action, Open Space & Sustainable Transportation.
This will be accomplished by integrating best practices for urban forestry throughout the
community and landscape in order to accrue the multiple benefits that trees provide,
including shading and cooling, beautification, habitat, stormwater retention, and carbon
sequestration. Properly maintaining the current inventory of trees and planting additional
trees to grow the living canopy is a best management practice.
Most urban forests, including the City’s urban forest, are especially vulnerable to climate
change including drought and destructive pests or disease. Some strategies to reduce
the impacts of climate change on the City’s urban forest include:
1. Enhance taxonomic, functional, and structural diversity.
2. Alter urban ecosystems toward new and expected climate conditions.
3. Maintain or increase extent of urban forests and vegetative cover.
4. Sustain or restore fundamental ecological functions of urban ecosystems.
5. Reduce the impact of physical and biological stressors on urban forests.
Leveraging the City’s urban forest to mitigate impacts of climate change can provide the
following benefits:
1. Activate social systems (people) for equitable climate adaptation, urban f orest, and
human health outcomes.
2. Reduce the impact of human health threats and stressors using urban trees and
forests.
3. Promote mental and social health in response to climate change.
4. Promote human health co-benefits in nature-based climate adaptation.
The City’s urban forest is comprised of both private and public trees in public rights -of-
way (streets), parks, City facilities, in creek areas, open spaces and private property. The
main focus of this report and study session is targeted at public rights-of-way, parks, and
City facilities.
Urban Forest Services Program
The City’s Urban Forest Services Program (UFS) in the Public Works Department is
responsible for the urban forest that is located within City’s public rights -of-way, parks,
and facilities. Trees located within riparian areas and open space are managed by Parks
and Recreation Department’s Ranger Services Program with oversight and guidance
provided by the Administration Department’s Office of Sustainability and Natural
Resources.
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UFS urban forest responsibility include the planting and maintenance of trees within the
previously mentioned areas as well as code enforcement responsibilities for adjacent
properties, review of private development projects, administration of the City’s Tree
Regulations that are in the Municipal Code Chapter 12.24, as well as staffing the Tree
Committee, the City’s advisory body related to urban forest issues. Specifically, UFS is
the lead program for:
Proactive & Responsive Maintenance
Community Education & Outreach
Tree Plantings
Staffing of the Tree Committee
Community Partner Liaison
Tree Removal Applications
Municipal Code Enforcement
Heritage Tree Program
Development Review
Pest Management
Historically, the program was
staffed by a City Arborist/Urban
Forest Supervisor, three Urban
Foresters, and at times, part
time staff to assist with
maintenance and development
review pertaining to tree
removals and plantings. In
2020, the program lost 75% of
its regular staffing to
retirements and long-term
injuries. Prior to this, in 2017,
the program became impacted
with field staff injuries which
drastically reduced the level of
maintenance performed and
resulted in a growing backlog of
maintenance needs. Due to prolonged injuries and other challenges within the program,
this created an ideal time to evaluate the program’s managed assets, workload and
organization. During this time an updated tree inventory has been completed as well as
a program and organizational assessment. While this assessment work was underway
maintenance was completed using a pruning contractor.
Tree Inventory
The City recently assessed and updated
the inventory information of public trees
located within City’s public rights-of-way,
parks, and facilities. The update inventoried
approximately 13,000 trees and identified
locations where trees previously were
located (tree stumps as well as vacant
planting sites).
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The City obviously has many more trees located in creeks, open spaces, and private
property; however, the trees inventoried are within the “urban” environment and have an
increased liability and thus require a higher level of maintenance and documentation.
During the assessment, the trees species, size, health, and other factors such as utility
line conflicts or tree caused infrastructure damage were captured. This updated data has
given UFS a clear understanding of the needs of the urban forest it manages. UFS
recognizes the importance of consistent documentation for future maintenance and
inspections as identified on page 7 of Attachment A
Tree Maintenance
The UFS has historically used contract services for larger pruning jobs. Due to a growing
backlog of tree maintenance needs, in 2019 the contract service budget was increased
from $50,000 to $225,000 on an on-going basis. This on-going contractor-based funding
has worked well to complete additional maintenance work. Due to the increased funding
being directed to a contractor, a new Request for Proposal s was released, and the City
selected West Coast Arborist (WCA) as the successful contractor. WCA specializes in
municipal tree care and is an industry leader in urban forest management. Due to the
successful results of this directed funding, contract funding was again augmented using
available one-time funding to $450,000 annually in 2021 through the end of the 2021 -23
Financial Plan.
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Since transitioning to contracted area pruning in 2021, four of the City’s nine Pavement
Management Zones and hundreds of service request have been completed. Through
this process, it has become evident that utilizing contract services for proactive stree t tree
pruning and tree planting projects is efficient and effective and a force multiplier for the
City. It has also become evident that responsive maintenance or service requests and
young tree care, is more efficient and cost effective when completed by staff. Historically,
the UFS Program responds to approximately 400 service requests annually for limbs
down and minor pruning related to safety or tree health concerns. Utilizing contract
services for area pruning and an in-house crew for emergency response, service request,
young tree care, and watering is a recommendation on page 27 of Attachment A.
Tree Plantings
Tree Plantings by the UFS Program have traditionally occurred in an ad hoc fashion by
staff leveraging Arbor Day Celebrations and neighborhood planting events to facilitate
this need. As identified in the Climate Action Plan, Pillar 6: Natural Solutions - the City
has undertaken an ambitious tree planting campaign of planting 10,000 new trees by
2035. It is anticipated that the majority of the 10,000 trees proposed for planting by 2035
will be San Luis Obispo native species that will be planted in City ope n space areas and
riparian corridors, although it is intended that streets, parks, schoolyards, private property,
and other locations will also receive plantings. 10 Tall remains a priority area of focus for
the City’s Climate Action Plan (CAP) 2022 Update.
A preliminary, estimated division of planting responsibilities is shown below:
10 Tall: Initiative to Plant 10,000 Trees by 2035 Number of Trees to be Planted
City of San Luis Obispo Tree Plantings
- Streets, Parks, Right-of-Way 1,000
- Creeks, Open Space 2,000
Engineering Standards for New Development 3,000
Volunteers and External Partners1 1,500
Community Members planting on private property
using complimentary trees
1,500
Trees planted to date since 2020 CAP
(approximate)
1,000
Total 10,000
The City is fortunate to have several community partners and volunteer networks, and
has benefited from over 400 tree plantings within the City since 2020. ECOSLO is a non-
profit organization who operates through community donations, grants, and service
contracts such as the City’s “Keys for Trees” program. Their Urban Tree Program
connects the community with tree planting and ongoing care in the urban environment of
the City of SLO. The Rotary de Tolosa service club has also been an active participant
in tree planting activities and remains committed to ongoing involvement. Cal Poly
students and faculty have been actively preparing a website that supports the 10 Tall
initiatives, which will be demonstrated for City Council and the Community at the Study
1 Trees to be planted in public right-of-way and open space by volunteers and external partners.
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Session.
With all tree plantings, the “Right Tree, Right Place2” concept is imperative. The City’s
Engineering Standards contain approved a Street Tree List for trees planted within the
public right-of-way. With the assistance of Cal Poly, these standards are in the process
of being updated, which will include a revised list of approved trees. The updated list will
contain species that are adaptive to the warmer climates with the least impacts to
infrastructure.
Tree plantings within the public right-of-way, and especially in the downtown area have
historically been challenging, due to the infrastructure damage cause d as trees mature.
The primary species, Ficus microcarpa ‘Nitida has caused millions of dollars in damage
and while beloved by some is a primary example that tree selection is critical. Roots of
mature trees can and often do affect sidewalks, curb and gutter, and underground utilities,
all which create a significant liability for the City. On average, the City receives 9.5 claims
annually for trip and falls, with a majority of these incidents involving tree related
infrastructure damage. A comprehensive tree replacement plan for trees within high traffic
right-of-way areas will help manage the long-term negative infrastructure impacts. This
will require the proactive and selective removal of mature species to mitigate damage.
Newly planted trees require a greater initial amount of care over mature trees. This
increased care is required for a minimum of the first three years, and sometimes longer.
For optimal long-term health, young tree care requires annual structural pruning and
weekly watering when located within the public right -of-way or in an area without
irrigation. Historically, the City has had one Urban Forester primarily assigned to young
tree care and watering. During the assessment period over the last 18 months, the City
has explored utilizing contract services for this work and found it to be cost prohibitive
and not in the best interest of the urban forest. Climate change and prolonged drought
periods have exacerbated this issue. The UFS Program is in alignment with the tree
planting recommendations on page 32 and 35 of Attachment A.
Commemorative Grove Program
The City has a Commemorative Grove Program in and around Laguna Lake Park area.
What started out as nine trees in 1989, has grown to over 400 trees today. These trees
have been planted by the City at the request of community members and special interest
groups who wish to commemorate a special event or person in their lives or significant
events in the lives of the people of San Luis Obispo. Due to current staffing levels, the
Commemorative Grove Program has been placed on hold. When active, the current fee
to plant a commemorative grove tree is $410.00. Some of the current challenges with
this program is the fee paid by community members does not cover the cost of the
planting, maintenance and watering until tree becomes established, as well as potential
conflict with the future expansion of amenities at Laguna Lake Park 3. As identified on
page 32 of Attachment A, the location of the Commemorative Grove will be discussed
2 The City has planted many “wrong” trees and/or in the “wrong” place and thus a disproportionate
amount of funding is spent on trimming, removal, infrastructure repair, etc.
3 The City collected over $3 million dollars is park fees from the San Luis Ranch development to mitigate
for needed active park amenities.
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with the community as part of the Laguna Lake Park Strategic Plan.
Tree Removals
Tree Removals within the City are regulated by section 12.24.090 of the Municipal Code
and are separated by Construction and Non-Construction removals. In 2019, the tree
ordinance was amended to allow for a more objective criteria when reviewing tree
removal applications. The former tree ordinance included highly subjective standards for
Non-Construction removals that proved challenging in guiding and clearly defining the
rationale behind tree removal decisions. The standards the Tree Committee could use to
either approve or deny the removal of a tree were:
a. The Tree is causing undue to the property owner. Normal routine maintenance
does not constitute a hardship, i.e., cleaning of gutters, leaf raking, pruning or root
intrusion into a failed sewer lateral.
b. Removing the tree promotes good arboriculture practice; or
c. Removing the tree will not harm the character or environment of the surrounding
neighborhood
To make this section of ordinance less subjective, section 12.24.090 was revised to allow
removal for the following reasons, if approved by the applicable decision maker, which is
also identified in the ordinance.
a. The tree is an imminent hazard to life or property, and removing it is the only
feasible way to eliminate the hazard.
b. The tree is dead or dying or diseased or damaged beyond reclamation.
c. The tree’s roots are causing severe damage to public or private property, and
removing the tree is the only feasible way to eliminate the damage.
d. The tree is affected by structural defects and/or deficiencies that will limit lifespan.
e. The tree is densely clustered amongst other trees and the requested tree removal
promotes good arboricultural practice.
f. The tree is obstructing vision, access, or mobility of public traffic.
g. The requested tree removal is necessary to alleviate a demonstrated and ongoing
maintenance burden for the property owner exceeding routine tree maintenance.
The ordinance was also revised to improve the process for Construction related removals.
One of the focal points of concerns for tree removals regarding development, was the
scope and timing of the Tree Committee’s involvement where tree(s) are a component of
a project. Formerly, the Tree Committee would only consider such removals if the City
Arborist recommended denial of the tree removal request. If the Tree Committee
concurred with the City Arborist’s recommendation to deny the application, the application
would then need to be heard by the City Council. The former process would often cause
confusion and place unnecessary burden on the applicant, staff, Tree Committee, and
City Council.
Another driving factor in the 2019 ordinance revision was the implementation of the
Housing Crisis Act (HCA). The HCA indicates that if a proposed housing development
project complies with the applicable general plan and zoning standards in eff ect at the
time the application is deemed complete , the City shall not conduct more than five
hearings, including any appeals of determinations made at these hearings, in connection
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with the approval or disapproval of the housing development project.
The ordinance update pertaining to development was intended to provide the Tree
Committee with an opportunity to review development projects early in the review process
and provide recommendations on tree removal and compensatory planting needs prior to
final development approval. Currently, if the Construction related tree removal is heard
by the Tree Committee, the project is reviewed for consistency with the Tree Ordinance
and a recommendation is made to the decision maker, which is dictated by the
development project designation.
Council input is specifically requested regarding compensatory planting requirements for
tree removal. Currently, if a tree is approved for removal, that tree is required to be
replaced at a minimum with one new tree if planted on the project site and two new trees
if planted off-site. Council could direct staff to strengthen this requirement related to
development projects and thereby encouraging the Tree Committee and the development
community to plant a higher ratio, but it should be noted that each and every tree
regardless of age and size is regulated on a parcel being developed and subject to
compensatory planting.
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The Tree Committee can recommend a higher ratio of compensatory plantings to the
decision maker since the compensatory planting requirement is a minimum and not a
maximum requirement. This information was recently discussed with the Tree Committee,
and they now have a better understanding of their role and ability to guide future
development projects to benefit the urban forest.
While staff’s recommendation is to work with the Tree Committee to better understand
their role in the development process and allow the Tree Committee to size compensatory
planting requirements on a project-by-project basis to ensure developments impacts on
the urban forest are correctly addressed; Council could direct staff to develop new
compensatory planting ratios for development projects. If Council chooses to develop a
more prescribed table for compensatory pla ntings related to development, Council may
also want to reconsider the Tree Committee’s role in development projects and whether
using one of the available five advisory committee meetings for development projects is
the best use of advisory body input to shape development projects. For Council’s
consideration below is a table which compares the City of San Luis Obispo’s
compensatory planting requirements with the cities of Santa Barbara and Monterey.
Compensatory Planting Requirements for Development
SLO Santa
Barbara Monterey
Onsite Plantings 1:1 1:14 3:1
Offsite Plantings 2:1 1:1 3:1
Urban Forest Partners
As noted, currently the urban forest is managed by the UFS Program in the Public Works
Department, the Office of Sustainability and Natural Resources in the Administration
Department, the Community Development Department, and the Parks and Recreation
Department. Recommendations of changes to the current program structured were
offered within the Organizational Assessment. City staff has discussed different structures
that would create efficiencies and better align duties with the applicable department. If
the City chooses to further bifurcate the UFS Program across departments, an Urban
Forest Team will be vital to the future success of the program. These recommendations
can be found on page 68 of Attachment A.
The City is very fortunate to have so many external community partners within the region
such as ECOSLO, Cal Poly, Downtown SLO, and PG&E. Increased coordination
between these entities and others will be necessary in meeting long term urban forest
goals. One of the recommendations within the Organizational Assessment is currently in
progress, which is the creation of a Volunteer Coordinator within the Parks and
Recreation Department. The Volunteer Coordinator position is an exciting development
that is expected to assist with the coordination and management of community
partnerships and events like Arbor Day and neighborhood plantings. Recommendations
for strengthening of external partnerships can be found in pages 61 - 64 of Attachment A.
4 Oak Tree removals require a 3:1 compensatory replanting
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Existing UF Org Structure Proposed UF Org Structure
Community Forest Plan
The Community Forest Plan (CFP) included in Attachment C of this report is currently in
draft form and will be presented to Council later this year. The Plan’s goals and objectives,
as presently envisioned, are provided below. These concepts were aggregated from 11
stakeholder interviews conducted specifically for this project, along with extensive review
of academic literature and other cities’ urban forest management plans. The goals of the
CFP include:
1. Maintain and expand San Luis Obispo’s urban forest in order to maximize
environmental, social, and economic benefits for all, while minimizing undesirable
conditions.
2. Emphasize the planting and care of climate-ready trees in locations where they will
have the greatest chances of success in environmental conditions that are rapidly
becoming more challenging.
3. Foster a spirit of collaboration between and within City departments that are
involved in urban forest management, as well as between the City and other local
stakeholders including community groups, non-profit organizations, utilities, other
cities, Cal Poly, other State agencies.
4. Educate and seek the involvement of City residents and visitors, including
historically marginalized groups, in order to obtain their buy-in and support for a
thriving urban forest.
Each objective in the CFP contains from one to a dozen implementation actions . Below
is a table that links objectives to goals as indicated in the CFP .
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Community Forest Plan Overview
Plan Objective Goal
Objective 1.1: Design/Implement Program; Accrue and Analyze Data 1,3,4
Objective 1.2: Strengthen Maintenance Practices; Clear Backlog 1
Objective 1.3: Increase New Plantings/Implement 10 Tall Initiative 1
Objective 1.4a: Focus on Sustainability: Climate Resilience 1,2,4
Objective 1.4b: Focus on Sustainability: Lifecycle Perspective 1,2,3,4
Objective 1.4c: Focus on Sustainability: Soil Enhancement and
Stormwater
1
Objective 1.4d: Focus on Sustainability: Safety 1
Objective 1.4e: Focus on Sustainability: Water Conservation 3
Objective 1.5: Address Issues Unique to Downtown 1,2,3,4
Objective 1.6: Increase Outreach to Officials and the Public 3,4
Objective 1.7: Focus on Equity 1,2,3,4
Previous Council or Advisory Body Action
The San Luis Obispo City Council adopted the 2020 Climate Action Plan for Co mmunity
Recovery (2020 CAP) in August 2020. The 2020 CAP, under Pillar 6: Natural Solutions,
calls for a contemporary, holistic approach to urban forestry that includes an updated
urban tree inventory, a database and tracking system accessible to the City’s urban forest
partners, creation of a Community Forest Master Plan, and a goal to plant 10,000 trees
by 2035. Based on these objectives, in February 2021 the City Council identified a
strengthened and expanded urban forest as a Major City Goal for the 202 1-2023 Financial
Plan.
PUBLIC ENGAGEMENT
During the Organizational Assessment Study conducted by Davey Resource Group, an
online survey was conducted for community members to answer questions and provide
feedback regarding the City’s UFS Program. The online survey was linked to the City’s
website, and participation was encouraged through a press release, social media
advertisements, Tree Committee and City Council meetings, and signage throughout the
City’s parks and open space trailheads. The survey was very successful with 644
community member responses, the second highest of any urban forest assessment
completed by Davey Resource Group. The survey included 9 questions about community
members’ views on tree benefits, education, and outreach, UF S operations, and
preferences for future plantings. The survey offered participants to expand on their
answers and provided space for thoughts and suggestions at the end. The survey is
estimated to take approximately 10 minutes to complete which represents approximately
100 hours of stakeholder input from the survey alone. The complete survey and results
are available in Appendix E (page 118) in Attachment A.
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In addition to the online survey, Davey Resource Group interviewed a group of
stakeholders, which included City staff, Council and Tree Committee members,
community partners, and Cal Poly faculty. To prepare for the Climate Action Plan 2023-
27 Work Program, a series of technical stakeholder meetings were held over the summer
of 2022 that focused, in part, on the urban forest and tree planting in creeks and open
space areas. Lastly, department staff has been discussing the different assessments
with the Tree Committee over the past 18 months, and most recently on December 5,
2022.
CONCURRENCE
Over the past 18 months, the Public Works Department has worked internally with
Community Development, Parks and Recreation, and the Office of Sustainability &
Natural Resources on the reorganization and improvement of the UF S Program. Staff
within these departments concur with the proposed direction of the program to gain
efficiencies and better serve the community. As mentioned in the Public Outreach section,
staff has consulted with the Tree Committee during the transition period and incorporated
their feedback into the existing work plan.
ENVIRONMENTAL REVIEW
The California Environmental Quality Act (CEQA) does not apply to the recommended
action in this report, because the action does not constitute a “Project” under CEQA
Guidelines Section 15378. As a study session, this item is informational only and is not
binding on future actions.
FISCAL IMPACT
Budgeted: No Budget Year: 2022-23
Funding Identified: No
Fiscal Analysis:
Funding
Sources
Total Budget
Available
Current
Funding
Request
Remaining
Balance
Annual
Ongoing
Cost
General Fund $ N/A $ - $ - $ -
State $ - $ - $ - $ -
Federal $ - $ - $ - $ -
Fees $ - $ - $ - $ -
Other: $ - $ - $ - $ -
Total $ N/A $ - $ - $ -
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This study session itself does not have any direct fiscal impacts. Below are historical
funding levels for the UFS Program, as well as a list of options for program component
funding that have been recommended for future operations with the associated costing.
While the historic funding level has marginally decreased from the peak funding provided
in the 2019-20 fiscal year, accomplished maintenance work has dramatically increased
in the 2022-23 Fiscal Year due to funding augmentation, contract management approach,
and selected vendor providing services.
Historical Urban Forest Funding
2018-19 2019-20* 2020-21* 2021-22* 2022-23*
$755k $1.1M $1.1M $1,070,741 $906,814
*One-time funding increase to facilitate additional contract pruning
Existing Phased Approach Community Vision
Staffing $264k5 $380k6 $465k7
Maintenance $225k $370k $515k
Planting - $50k $100k
Total8 $489k $800k 1,080k
The table above shows the cost to achieve the urban forest goals in three basic categories
which are staffing, maintenance contracts and plantings. The existing column shows the
funding that the UFS Program would typically receive in the 2023-25 Financial Plan
without augmenting levels of service provided to the urban forest. The phased approach
column shows the cost to achieve the communities vision, augmenting the urban forest
over time to achieve community objectives by 2035. The Community Vision funding level
would achieve the desired urban forest maintenance cycle and planting needs in
approximately five years. Staff is recommending that this funding be reviewed with the
upcoming 2023-25 Financial Plan so that Council may have the benefit of looking at the
entire City budget to determine where resources are best placed to meet community
objectives.
ALTERNATIVES
Council could provide feedback in areas other than the example questions listed above.
ATTACHMENTS
A - SLO Urban Forest Organizational Assessment, Davey Resources Group
B - Tree Inventory Overview Report, West Coast Arborists
C - City of SLO Community Forest Plan: Professional Project Report, City & Regional
Planning Department, California Polytechnic State University
D - Pruning and Planting Plan from Davey Resources Group
5 Funding amount for one City Arborist and One Urban Forester
6 Funding amount for one City Arborist and two Urban Foresters
7 Funding amount for one City Arborist, Two Urban Foresters and one Tree Trimming Assistant.
8 Fund amount does not represent the total cost of the urban forest program. Just those cost in the three
categories of staffing, maintenance and planting.
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San Luis Obispo Summary Report
Urban Forestry Organizational Assessment
2021
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San Luis Obispo Summary Report
Urban Forestry Organizational Assessment
2021
Prepared for:
City of San Luis Obispo Public Works Department
990 Palm Street
San Luis Obispo, CA 93401
Prepared by:
Davey Resource Group, Inc.
295 South Water Street, Suite 300
Kent, OH 44240
www.davey.com/drg
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Table of Contents
Executive Summary 1
Introduction 3
Urban Forest Resource 5
Urban Forest Canopy 5
Community Tree Resource 6
Tree Inventory Management 7
Equity 10
Resource Threats 11
Climate Change 11
Drought 12
Pests and Pathogens 12
Resiliency Strategies 14
Operations and Programs 25
Services and Programs 26
Service Requests 26
Tree Pruning 27
Clearance and Visibility 30
Heritage Trees 30
Tree Planting 31
Commemorative Tree Program 33
Tree Selection 35
Irrigation 37
Tree Removal 39
Debris and Wood Utilization 40
Emergency Response 43
Community Engagement and Outreach 43
Development 45
Design 48
Safety 51
Urban Forest Partners 53
Internal Partners 53
Parks and Recreation Department 54
Community Development Department 55
Fire Department 56
Administration Department - Office of the City Manager 57
Administration Department — Office of Sustainability 58
Public Works Department — Maintenance Operations (Parks) 59
Advisory Bodies 60
San Luis Obispo Tree Committee 60
San Luis Obispo City Council 62
External Partners 63
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Environmental Center of San Luis Obispo (ECOSLO) 63
Downtown SLO 64
California Polytechnic State University (Cal Poly) 65
Organizational Structure and Staffing 67
Staffing 67
Equipment 71
Contract Management 72
Funding 74
Policy and Regulation 77
Federal and State Law 77
Endangered Species Act 77
Migratory Bird Treaty Act (MBTA) 77
Vegetation Management Standards 77
California Urban Forestry Act 77
Model Water Efficient Landscape Ordinance (MWELO) 78
California Global Warming Solutions Act 78
California Solar Shade Control Act 78
Climate Adaptation Actions for Urban Forests and Human Health 78
Guiding Documents for the Urban Forest 79
Municipal Code 79
San Luis Obispo General Plan 2035 80
Climate Action Plan for Community Recovery 82
2021-23 Financial Plan 83
Engineering Standards 83
Management and Performance Audit of the Public Works Department 84
Estimating Urban Canopy Cover in San Luis Obispo 84
San Luis Obispo Creek Stormwater Resource Plan 84
Parks and Recreation Blueprint for the Future 2021-2041 85
Resilient SLO 85
Additional Planning Documents 85
Benchmark Community Survey 87
Analysis of Sustainability Indicators 93
The Trees 93
The Players 95
The Management Approach 96
Conclusion 97
Appendix A: References 101
Appendix B: Industry Standards 104
Appendix C: Estimated Time on Services 107
Appendix D: Sustainability Indicators 108
Appendix E: Community Survey 118
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Tables
Table 1: Tree Canopy by Land Use in San Luis Obispo (Nessen, 2012) ...................................................... 6
Table 2: Sustainable Indicators ............................................................................................................................... 94
Table 3: Tasks and Estimated Time Spent by Urban Forest Services Staff ........................................... 107
Table 4: The Trees ...................................................................................................................................................... 108
Table 5: The Players ................................................................................................................................................... 111
Table 6: The Management Approach ................................................................................................................. 114
Figures
Figure 1: San Luis Obispo Urban Core Boundary in Red (Left) and Canopy Cover (Right) (Nessen,
2012) .................................................................................................................................................................................... 5
Figure 2: Tree Condition ............................................................................................................................................... 6
Figure 3: Relative Age Distribution ........................................................................................................................... 7
Figure 4: Tree Removal Flow Chart ........................................................................................................................ 40
Figure 5: Current Staffing Structure of Urban Forest Services .................................................................... 67
Figure 6: Staffing Recommendations ................................................................................................................... 70
Figure 7: San Luis Obispo Community Member Opinions on the Most Important Benefits of
Trees .................................................................................................................................................................................. 87
Figure 8: Community Member Opinions on the Most Important Environmental Benefit from
Trees .................................................................................................................................................................................. 88
Figure 9: Community Member Opinions on the Most Important Socioeconomic Benefit from
Trees .................................................................................................................................................................................. 88
Figure 10: Community Member Opinions on Where it is Most Important to Plant More Trees ... 89
Figure 11: Community Member Opinions on Encouraging Tree Planting on Private Property ..... 89
Figure 12: Community Member Awareness and Interactions with the Urban Forestry Program .. 90
Figure 13: Community Member Opinions on the Level of Care Provided for Community Trees .. 90
Figure 14: Community Member Opinions on Whether Urban Forest Services and Programs are
Equally Accessible to all Residents ........................................................................................................................ 91
Figure 15: Community Member Opinions on Topics of Education and Outreach of Interest ........ 91
Page 499 of 748
Glossary of Acronyms
American National Standard Institute (ANSI)
Best Management Practices (BMP)
California Department of Forestry and Fire Protection (CAL FIRE)
California Polytechnic State University (Cal Poly)
Capital Improvement Project (CIP)
Diameter Breast Height (DBH)
Environmental Center of San Luis Obispo (ECOSLO)
Full Time Employee (FTE)
Integrated Pest Management (IPM)
International Society of Arboriculture (ISA)
Invasive Shot Hole Borer (ISHB)
Occupational Safety and Health Administration (OSHA)
Pacific Gas and Electric (PG&E)
Part Time Employee (PTE)
Rights-of-way (ROW)
San Luis Obispo (SLO)
Tree Risk Assessment Qualification (TRAQ)
Tree Care Industry Association (TCIA)
Urban Forest Strategic Plan (UFSP)
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1 Executive Summary
Executive Summary
The city of San Luis Obispo (SLO) considers trees and canopy cover important assets for building
a vibrant community. Recognizing that the urban forest improves the quality of life for residents
and visitors, SLO initiated an Urban Forestry Organizational Assessment of the Public Works
Department - Urban Forestry Division during a time of transition and renewed emphasis on the
importance of the urban forest in climate action initiatives. The results of the assessment
included a summary of the challenges and opportunities faced by Urban Forest Services and
provided initial recommendations for the advancement of the urban forestry program and
future urban forest planning initiatives.
During the review process, inadequate inventory management and reactive maintenance of the
public tree resource were common themes. As of 2008, the public tree inventory includes 17,983
trees along streets, in parks, and city facilities, the majority of which are in fair condition. Current
estimates indicate there are 20,000 plating sites across the city, 15-25% of which are vacant
(Climate Action Plan 2020). The Urban Forestry Organizational Assessment identified
recommendations for generating and maintaining a current and up-to-date inventory,
establishing more proactive maintenance, increasing in-house staffing levels to address service
requests and work orders, and developing comprehensive schedules and work plans to provide
routine maintenance.
Another common concern brought up during the review process was around the loss of trees as
a result of the recent increase in development. While San Luis Obispo’s urban forestry program
has a strong tree protection ordinance that prohibits the removal and pruning of public and
private trees, development is a threat to existing trees and source of competition for space for
additional tree plantings. Future planning should consider ways to enhance protections for
existing trees (including exploration into the role of the Tree Commission in tree protection) and
ensure mitigation plantings remain in perpetuity.
The Urban Forestry Organizational Assessment is the first step in the path toward re-enacting a
strong urban forestry program, addressing the identified challenges, and exploring challenges
further during future planning processes. Information gained from this assessment and up to
date information on the public tree resource will help ensure that the necessary resources are in
place to care for the public tree resource and provide a long-term vision for the urban forest.
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Executive Summary 2
Page 502 of 748
3 Introduction
Introduction
The city of San Luis Obispo (SLO) places a great emphasis on creating a sustainable, resilient,
livable, and vibrant community and both the community and the organization recognize and
celebrate the role the urban forest plays in providing the quality of life for visitors and the
community. Community members are actively involved and passionate about trees. This is
evident from the many volunteers involved in tree planting, maintenance, and advocacy as well
as the community’s consistent support of local revenue measures that provide funding for tree-
related programs. The City’s achievements around the urban forest include 38 years as an Arbor
Day Foundation “Tree City USA” and two International Society of Arboriculture Gold Leaf
Awards. San Luis Obispo’s urban forest is made up of trees on public and private property. The
City’s Urban Forest Services, within the Public Works Department, is responsible for the care of
approximately 20,000 trees along streets, in parks, and at city facilities.
As outlined in the Climate Action Plan and the Financial Plan, the City intends to develop an
Urban Forest Strategic Plan (UFSP) in the near future. To begin that process, the City of San Luis
Obispo Public Works Department contracted with Davey Resource Group, Inc. (DRG) to review
the urban forest program, including the current structure and operations, background
documents, and existing policies. DRG also engaged key partners and community members and
conducted an online survey to gauge community awareness and support for the urban forest.
This document summarizes the findings from this review and provides recommendations for
consideration during the development of an Urban Forest Strategic Plan. The review process did
not include an assessment of the entire urban forest (trees on private property, natural areas,
and riparian buffers) or engagement with other governing bodies. Therefore, the findings
provided in this report are not a comprehensive account of every consideration that should be
addressed by a UFSP. DRG recommends that future planning phases include additional
exploration on the role of the Tree Committee, objective design standards, compensatory
planting requirements resulting from development, along with expanded engagement with key
stakeholders and the community. Furthermore, Urban Forest Services is in a transition period
and recently began to contract tree maintenance and inventory work. The next phase of
development of a UFSP should assess any new information gathered on the resource from these
activities.
The vision for San Luis Obispo is of a “sustainable community within a diverse
natural and agrarian setting, which is part of a larger ecosystem upon which its
existence depends. San Luis Obispo will maintain its healthy and attractive
natural environment valued by residents, its prosperity, and its sense of safety
and community, within a compact urban form…”
-Land Use Element of the General Plan
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Introduction 4
The findings in this report reflect input that was received from stakeholders and document
known challenges and opportunities that should be considered by the City to make decisions
around Public Works Department services and staffing levels. Each section of this report
documents and benchmarks current conditions, challenges, and opportunities, and provides
initial recommendations for the advancement of the urban forestry program and the
development of a UFSP.
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5 Urban Forest Resource
Urban Forest Resource
An urban forest is a living and dynamic resource, changing over time and in constant response
to its environment. The health and stability of the urban forest can be influenced by many
factors, including pruning, irrigation, climate change, weather fluctuations, emerging pests and
disease, as well as development and new tree planting. A complete understanding of the current
extent of tree canopy within City boundaries, as well as the structure, condition, and
maintenance needs of trees managed by the urban forestry program is essential to making the
best possible management decisions.
Urban Forest Canopy
When looking at a subset of the City boundary that contains urbanized areas within San Luis
Obispo, there are 1,050 acres of tree canopy for an overall canopy cover of 13.2% (Figure 1;
Table 1). Canopy cover varies by land use category and is highest for office properties (19.6%)
and residential areas (19.2%) and lowest in business parks (2.5%). Tree canopy in residential
areas ranges from 15.4% in medium density to 20.6% in low density, with medium high and high
density falling in between (Nessen, 2012).
Figure 1: San Luis Obispo Urban Core Boundary in Red (Left) and Canopy Cover (Right) (Nessen, 2012)
Page 505 of 748
Urban Forest Resource 6
Table 1: Tree Canopy by Land Use in San Luis Obispo (Nissen, 2012)
Land Use Category Acres Canopy
Acres Canopy %
Residential 3,313.1 635.7 19.2
Public Facilities 981.4 91.8 9.4
Undeveloped 1,171.5 84.8 7.2
Manufacturing 1,013.0 76.9 7.6
Commercial 737.1 69.3 9.4
Office 232.4 45.6 19.6
Park 220.2 38.2 17.3
Business Park 311.7 7.9 2.5
Total 7,978.2 1,050.0 13.2
Community Tree Resource
The tree inventory includes 17,983 trees along streets, in medians, parks, and at city facilities.
Although the inventory is outdated (last updated in 2008), the data is estimated to be between
90-95% accurate. The Climate Action Plan (2020) estimates there are currently 20,000 trees and
additional planting opportunities in 15-25% of sites that are vacant.
Tree condition is an indication of how well trees are managed and how well they are performing
in the region and in each site-specific environment (e.g., street, median, parking lot, etc.).
Condition ratings can help managers anticipate maintenance and resource needs, as well as give
a glimpse on the benefits the trees provide. The amount
and distribution of leaf surface area is the driving
force behind a tree’s ability to produce benefits
for the community (Clark et al. 1997). Trees
rated in the good or better category typically
have full, healthy canopies and therefore
maximize benefits to the community. Thirty
seven percent of San Luis Obispo’s
community tree inventory is in good or
better condition (Figure 2). Typically trees in
fair condition have minor structural
problems, but reasonable vitality and therefore
also provide considerable benefits to the
community.
Excellent
0.4%
Very Good
0.9%Good
35.2%
Fair
54.8%
Poor
7.8%
Critical
0.1%Dead
0.8%
Figure 2: Tree Condition
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7 Urban Forest Resource
The relative age distribution of a species and for the overall resource can be approximated with
consideration of the diameter (DBH1) of individual trees. The age distribution of a tree
population influences present and future costs as well as the flow of benefits. An ideally aged
population allows managers to allocate annual maintenance costs uniformly over many years
and assures continuity in overall tree canopy coverage and associated benefits. A desirable
distribution has a high proportion of young trees to offset establishment and age-related
mortality as the percentage of older trees declines over time (Richards, 1982/83). San Luis
Obispo’s inventoried trees show a nearly ideal age distribution (Figure 3).
Figure 3: Relative Age Distribution
Maintaining diversity in a community tree resource is important. Dominance of any single
species or genus can have detrimental consequences in the event of storms, drought, disease,
pests, or other stressors that can severely affect a community tree resource and the flow of
benefits and costs over time. Having a diverse tree resource provides resiliency to the urban
forest. Recognizing that all tree species have a potential vulnerability to pests and disease, urban
forest managers have long followed a rule of thumb that no single species should represent
greater than 10% of the total population and no single genus more than 20% (Santamour,
1990). There are 298 unique species in San Luis Obispo’s tree inventory. The most abundant
species, coast live oak (Quercus agrifolia), represents 10% of the overall resource. All other
species represent less than 5% of the overall resource and fall within these recommendations
but striving for greater diversity could provide even more benefits for resiliency.
Tree Inventory Management
In the past, the City used a tree specific inventory management software (ArborPro) to inventory
community trees in rights-of-ways, streets, parks, city facilities, and heritage trees on private
property. In line with a recommendation from the 2011 audit of the Public Works Department,
the City integrated the tree inventory into Cityworks, an inventory management software used
to track multiple assets within the Public Works Department (Management and Performance
1 DBH: Diameter at Breast Height. DBH represents the diameter of the tree when measured at 1.4 meters
(4.5 feet) above ground (U.S.A. standard).
0%
10%
20%
30%
40%
0 ‐ 3 3 ‐ 6 6 ‐ 12 12 ‐ 18 18 ‐ 24 24 ‐ 30 30 ‐ 36 36 ‐ 42 42+% of PopulationDBH Class (inches)
ideal age distribution
total population
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Urban Forest Resource 8
Audit of the Public Works Department, 2011). Since the transition, that began in 2013 and ended
in 2014, tree data has not been regularly updated in Cityworks, although staff does use
Cityworks to track tree removal inspections as they occur. Currently, the Public Works
Department is developing a request for proposals for a complete update of the tree inventory
maintained by Urban Forest Services.
Currently, partnering departments and organizations do not have access to the tree inventory.
For example, ECOSLO manages the inventory of trees the organization has planted in an online
format and cannot integrate with the City’s existing inventory. During maintenance, inventory
updates are conducted by contractors and occur in a separate program so data has to be
uploaded into Cityworks quarterly.
A complete, up-to-date tree inventory housed in a comprehensive management system will
strengthen the program. An inventory management system is a powerful tool that can be used
to track trees that require pruning or removal for risk mitigation, record current characteristics of
each tree (e.g., species, condition, size), map (GIS based) assets, develop maintenance cycles and
work plans, create real-time workflows, analyze work history, and share data amongst divisions
in the Public Works Department as well as other urban forest partners (Bond and Buchanan,
2006).
Challenges and Opportunities: Urban Forest Resource
Tree inventory is out of date and not regularly updated as work occurs.
The Public Works Department is planning to obtain a complete inventory of the
trees they manage.
The tree inventory has an approximate 10% error rate, with some errors in species
identification.
Urban forest partners provide the majority of new tree planting in rights-of-ways yet
do not have access to update the existing inventory program.
Tree canopy data is more than 10 years old and is not comprehensive.
The stocking level for trees maintained by Urban Forest Services is unknown and
vacant sites are not currently documented or tracked.
Staff struggles to document and maintain the tree inventory data, especially for
assets that require frequent maintenance.
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9 Urban Forest Resource
Recommendations for UFSP Planning: Urban Forest Resource
Complete a comprehensive update of the tree inventory that includes data on all
existing trees, vacant sites, stumps, and potential sites (per Climate Action Plan and
Strategic Budget Direction Report).
Use this information to better understand the stocking level and potential for
future planting.
Update inventory database (as needed) when inspections or maintenance occur (per
Climate Action Plan).
Confirm species
Update condition and maintenance needs (if applicable)
Update DBH
Analyze and correct misidentified species in the tree inventory.
Explore opportunities for assistance from Cal Poly students.
Allow urban forestry partners access to update the tree inventory.
Use administrative settings to control access and editable data
Conduct a full land-cover assessment, including impervious surfaces (per Climate
Action Plan).
Analyze historic change.
Explore canopy distribution and equity, especially for publicly managed areas
Explore canopy and planting potential.
Maintain historic records of tree maintenance, update data as trees are pruned or
removed and add new trees to the inventory as they are planted.
Determine and account for the time it takes to keep the inventory up-to-date as work
occurs for budgeting purposes.
Use a common database tracking system amongst Urban Forest Services, contractors,
ECOSLO, Office of Sustainability, Parks and Recreation, and any other partners so
there are not redundancies or lag times in accessing data.
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Urban Forest Resource 10
Equity
Equity is an initiative for the City’s Climate Action Plan and
Diversity, Equity and Inclusion is a Major City Goal in the
2021-23 Financial Plan. The City aims to consider the
distribution of the urban forest to increase the benefits from
trees, especially for residents most vulnerable to extreme
heat and flooding.
The City has the greatest ability to directly impact tree
planting on City property followed by trees within the City
limits (excluding properties owned by state and county
agencies). In all maintenance zones, trees in rights-of-way
currently receive the same level of service. Parks are
distributed throughout the community so that all residents
have access to trees and tree canopy. In general, newer
housing developments have more tree planting opportunities than what is available for houses
in older neighborhoods. If a planting site is vacant, residents have an opportunity to request a
tree.
Twenty percent of respondents to the online survey do not feel that urban forest services and
programs are equally accessible to all. The Urban Forest Strategic Plan process should consider a
comprehensive land-cover assessment, including analysis of rights-of-way, to explore
distribution and quality of tree canopy across the community. Additional community
engagement should explore concerns about equitable access to urban forest resources and
services.
20% of community
survey respondents
did not think that
Urban Forest Services
and programs are
equally accessible to
all.
Challenges and Opportunities: Equity
The current extent of tree canopy across the community is not known.
Equity is a City initiative, but currently there is not coordination between Urban
Forest Services and the Diversity, Equity, and Inclusion Task Force.
The online survey indicated that 63% of community members are not sure if Urban
Forest Services and programs were equally accessible to all and 20% feel they are
not.
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11 Urban Forest Resource
Resource Threats
Like all urban forests, San Luis Obispo's trees are vulnerable to numerous stressors and threats.
These threats may be specific to a particular host species, which means that the threat is more
isolated. Other threats, like climate change, can affect a broader range of tree species and could
result in significant loss in benefits and canopy cover.
Climate Change
Urban Forest Services recognizes that shifts in weather patterns are likely to alter species habitat
ranges and render some species less adapted to the region. Research on climate change in
complex urban ecosystems is challenging and still evolving. Although there is no clear
consensus on the future outcomes, it is thought that extraordinary weather events are likely to
increase in years to come. As temperatures rise and precipitation patterns fluctuate from
historical norms, existing trees must adapt or succumb to the changes in climate.
Impacts on the urban forest program may include:
Health and structural impacts on tree species that are not adapted to new and changing
conditions.
Increase in pests and disease as a result of changes in temperature, precipitation, and
tree stress.
Recommendations for UFSP Planning: Equity
Conduct a tree canopy and land cover assessment and explore the distribution of
tree canopy (particularly in ROW) by neighborhood, census tracts, and other
geographic metrics to better understand distribution and opportunities for
additional canopy.
Analyze canopy distribution, cover, and urban forest benefits for equitable
distribution, including for vulnerable populations.
○ Analyze canopy as it relates to flood zones and land surface
temperatures.
○ Create linkages in areas with high tree canopy fragmentation.
Explore the relationship between tree canopy and socioeconomic variables.
Coordinate with the Diversity, Equity, and Inclusion Task Force to identify gaps in
the equity of the urban forest.
Explore how urban forest services and programs can be more equitable in the
Urban Forest Strategic Plan development process.
Develop equity strategies around the urban forest.
Use trees to increase neighborhood wellness, aesthetics, and other quality of life
improvements (per 2021-23 Financial Plan).
Use trees to increase carbon sequestration and mitigate the effects of climate
change (per 2021-23 Financial Plan).
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Urban Forest Resource 12
Additional costs for mitigation (e.g., irrigation infrastructure) and tree removal for
marginal species.
Canopy loss, especially where key species (e.g., predominant species) become
marginalized.
Tree species can adapt to climate change by shifting their range (e.g., expanding northward and
to a higher elevation) or contracting (reducing) their range. In a study of North American tree
species, more than half were contracting their ranges in response to climate change (Zhu, et al
2012). With a potential for an increase in maladapted species in tree populations and the
potential for urban areas to exacerbate these stresses, it is important to incorporate new species
that are showing promise into ongoing tree planting and then proactively monitor and select
high performing species for additional planting.
Climatic events (e.g., storms, drought, wildfire), disease or pest outbreaks, land use changes, and
other stressors can severely affect the urban forest and the flow of benefits and costs over time.
Increasing species diversity and tracking species performance can help managers determine
suitable species and lessen the detrimental consequences in the event species are susceptible to
changes in climate and other pressures in the urban environment.
Drought
The recent droughts in California have led to a decrease in
urban trees throughout the state. Not only can drought be
the primary cause for a tree to die, but it can also
predispose trees to other stressors. Urban forest partners
and community members expressed concern that park
trees in San Luis Obispo have died from drought conditions
and also the need to focus future planting efforts on
drought tolerant species.
Pests and Pathogens
In some cases, pests or pathogens can result in significant tree damage or loss and/or be costly
to manage. Involvement in the global economy, close proximity to major ports, and a highly
mobile human population increase the risk of an invasive pest or pathogen to San Luis Obispo.
Pests of greatest concern have already been introduced to the state or neighboring
communities and other pests or pathogens could foreseeably have a huge impact on the tree
resource. Urban Forest Services continually monitors the tree resource for emergent pests and
pathogens. When unknown diseases are discovered, the causal agents are identified by a local
lab and management is determined based on the results.
Invasive Shot Hole Borers and Fusarium Dieback
The polyphagous shot hole borer and the Kuroshio shot hole borer (Euwallacea sp.) are invasive
beetles introduced from Asia. They are involved in a disease called Fusarium dieback, which is
present in Southern California. The polyphagous shot hole borer was first found in Southern
California in 2003 and now has established populations in Los Angeles, Orange, and Riverside
counties. It has recently spread to San Bernardino, Ventura, and Santa Barbara counties, and in
2016, a single beetle was found and caught in a trap in San Luis Obispo County (University of
“Ideally, less water
intensive trees would be
great across the city.”
-Survey Respondent
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13 Urban Forest Resource
California, 2021). Urban Forest Services has not observed this pest in San Luis Obispo, but
participates in the statewide invasive shot hole borer management program, coordinates with
the regional CAL FIRE representative specializing in forest pathology and entomology, and stays
up to date on what to look for and how to manage this pest.
The damage causes branch dieback, and over time can kill the tree (Eskalen et al. 2017). These
beetles have the potential to colonize healthy or stressed trees and have a large host range
consisting of more than 260 plant species. The invasive beetles feed on fungi that they carry into
heartwood tissues of the tree. Some of the introduced fungi are tree pathogens that disrupt the
flow of water and nutrients. Sometimes staining and gummosis can be seen around beetle entry
and exit wounds, and typically cankers have formed at these sites. The beetles feed on the
fungus rather than tree tissues (Umeda et al. 2016).
Citrus Greening
Similarly, citrus greening (Candidatus liberibacter asiaticus) is a bacterial disease spread by the
Asian citrus psyllid. The disease causes bitter, hard fruit production, and is among the most
concerning pests as it threatens the viability of California’s citrus crop. As citrus is an important
agricultural crop, there are quarantines in place to protect the industry. Because of the lack of
effective treatments, the typical treatments for non-agricultural trees are to destroy and dispose
of material appropriately and treat trees with pesticides (Grafton-Cardwell et al. 2019). In San
Luis Obispo, all incoming citrus trees are inspected by the county.
Sudden Oak Death
Sudden oak death (caused by the pathogen Phytophthora ramorum) is documented in many
coastal counties of California including the counties of Monterey, Santa Cruz, and Santa Clara
(California Oak Mortality Task Force, 2020). While primarily affecting coastal areas from
Monterey up to the Oregon border, there is a possibility of the disease spreading south to San
Luis Obispo (EDDMapS, 2021). Urban Forest Services has identified this disease as a threat. In
susceptible hosts, the pathogen can become systemic and girdle trees as quickly as one year
after infection (Daugherty and Hung, 2020). San Luis Obispo’s most abundant species, coastal
live oak (Quercus agrifolia) is highly susceptible to sudden oak death and incurs high mortality
rates upon infection.
Challenges and Opportunities: Resource Threats
Selecting species of trees that will be resilient in a changing climate, such as
selecting drought-resistant tree species that will perform well in dryer and hotter
climates.
Increasing potential for periods of prolonged drought.
Existing and emerging pests and disease.
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Urban Forest Resource 14
Resiliency Strategies
Severe impacts on the urban forest are anticipated as a result of climate change, including
increased management costs and loss of canopy from declines in overall tree health. Despite
anticipated negative outcomes for trees and the urban forest, the urban forest can be used as
a tool to adapt to climate change. Management strategies can increase resiliency in the urban
forest and also contribute to the overall resiliency of a community. It is important to
incorporate as many resiliency strategies as possible and strive to maintain a healthy urban
forest to better address climate change and pest and disease threats.
In recognition of the urban forests’ role in mitigating the effects of climate change, in 2021 the
USDA Forest Service published nine strategies to increase resilience in the urban forest and
communities to climate change, including the following (Janowiak et al. 2021):
Recommendations for UFSP Planning: Resource Threats
Update/develop a comprehensive species palette, including key characteristics,
such as
Size/height
Water needs/drought tolerance
Space requirements
Propensity to cause infrastructure conflicts
Fall color, flowers, fruit, etc.
Minimum planter size
Pest/disease resistance
Collaborate with researchers for newly recognized species that are expected to
perform well in the region/microclimates.
Explore tree palettes in regions with similar and projected climate.
Consider a policy requiring replanting a certain percentage of native and/or
drought tolerant species.
Continue to collaborate with local and regional experts (Extension,
Universities/Colleges, Nurseries, Landscape Architects, Researchers).
Emerging pests/disease and management strategies/treatments
Species selection and diversity
Partner with the SLO Climate Coalition on climate action initiatives that relate to
the urban forest.
Threats to the urban forest
Contribution or support from the urban forest
Ensure the urban forest is continues to be emphasized in future planning
documents (e.g., Resilient SLO).
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15 Urban Forest Resource
Activate social systems for equitable climate adaptation, urban forest, and human
health outcomes
Reduce the impact of human health threats and stressors using urban trees and forests
Maintain or increase extent of urban forests and vegetative cover
Sustain or restore fundamental ecological functions of urban ecosystems
Reduce the impact of physical and biological stressors on urban forests
Enhance taxonomic, functional, and structural diversity
Alter urban ecosystems toward new and expected conditions
Promote mental and social health in response to climate change
Promote human health co-benefits in nature-based climate adaptation
Strategy 1: Activate social systems for equitable climate adaptation, urban forest, and
human health outcomes
Effective response to climate change will require collaboration. Strategy 1 highlights the
importance of engaging the community and leadership as a means to help sustain the urban
forest, respond to climate change, and invoke broader policy to meet environmental justice
goals for the health of both trees and people.
The key adaptation methods or approaches include:
Address socio-ecological systems in early, comprehensive response.
Integrate urban forestry in climate planning and policy.
Address climate and health challenges of disadvantaged communities and vulnerable
populations.
The following are examples of how urban forest management can activate social systems for
equitable climate adaptation, urban forest, and human health outcomes:
Engage the Community in the Urban Forest — When a community recognizes the
many benefits provided by trees, supports the urban forest, and engages in activities
related to trees, the community is more aware of their responsibility in the care of
public and private trees and the resilience of the urban forest to climate change.
Share Common Goals and Collaborate with Urban Forestry Partners — Partner with
other green industry leaders, neighboring communities, regional groups, nonprofits,
businesses, utility and state agencies, and other municipal agencies to work together to
support the urban forest and climate change response efforts.
Capitalize on Tree Planting Efforts to Address Climate Based Impacts —
Communities of black, indigenous, and other people of color have been disadvantaged
by racially motivated policies, like redlining. Early studies suggest that one of the
impacts of such policies is fewer trees in areas where more of these groups live.
Planting trees is hugely beneficial, but through the strategic planting of trees, not only
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Urban Forest Resource 16
can some of these disparities in canopy distribution be alleviated, but climate concerns
can also be addressed.
Create New and Expand Existing Urban Natural Areas — Promote greater species
diversity, expand canopy cover and the urban forest through creating, restoring, and/or
expanding the size of urban natural areas.
Strategy 2: Reduce the impact of human health threats and stressors using urban trees
and forests.
The key adaptation methods or approaches include:
Reduce extreme temperatures and heat exposure.
Improve urban air quality conditions.
Anticipate and reduce human health impacts of hazardous weather and disturbance
events.
The following are examples of how urban forest management can be used to reduce impacts of
human health threats and stressors:
Achieve Optimal Canopy Cover — The benefits of trees are directly attributed to their
canopy. To optimize the benefits of canopy, managers should seek to achieve optimal
canopy cover and equitable distribution across a community. Use of accurate, high-
resolution canopy data can approximate optimal canopy cover levels. By identifying
canopy potential, managers can work with the community to set long-term canopy
goals and promote the preservation of existing trees on private property and
incentivize the planting of trees on private property.
Reduce Urban Heat Islands — Urban heat islands contribute significantly to high
temperatures in urban areas and can result in consequences to human health. Some of
the effects of urban heat islands can be abated through the strategic planting of trees
to shade hardscapes (e.g., parking lots, streets, other impervious surfaces).
Create “Green Screens” — Exhaust from cars and trucks are a main source of air
pollution (California Office of Environmental Health Hazard Assessment, 2021).
Communities adjacent to major roads and highways are heavily exposed to air
pollutants and noise. Planting trees and creating “Green Screens” near major emissions
sources (especially adjacent to high-speed transportation corridors) and selecting tree
species with specific traits for particulate capture can result in improvements in air
quality (Janowiak et al. 2021).
Establish Plans and Funding Reserves in Case of Natural Disaster — A variety of
consequences can result from severe weather events and changes in climate. The ability
to adapt and recover from damages to infrastructure, property, community health
impacts, and environmental contamination is critical to our way of life (Carter et al
2015). A disaster management plan is in place in the case of trees damaged during
extreme weather events. The plan includes staff roles, contracts, response priorities,
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17 Urban Forest Resource
debris management and a crisis communication plan. Staff are regularly trained and/or
updated.
Strategy 3: Maintain or increase extent of urban forests and vegetative cover.
A healthy urban forest is more able to withstand stresses, including the direct and indirect
impacts of climate change. By increasing the extent of urban forests and canopy cover, the
benefits they provide and climate change mitigation functions they provide can be maximized.
The key adaptation methods or approaches include:
Minimize forest loss and degradation.
Maintain existing trees through proper care and maintenance.
Restore and increase tree, forest, and vegetative cover.
Sustain sites and ecosystems that provide high value across the landscape.
The following are examples of how urban forest management can support the maintenance and
expansion of canopy cover:
Provide Clear Guidance and Protections Through a Tree Ordinance — A tree
ordinance provides enforceable guidance for adequate maintenance and protection of
the canopy cover provided by significant trees on private property. With strong
enforcement, the loss of individual trees will not result in significant losses to the
overall canopy cover.
Define and Protect Heritage Trees — Trees are long lived organisms and mature
trees provide the greatest benefits. Defining heritage trees as those trees that are
especially significant to the community promotes their protection and recognizes the
benefits of mature or unique trees, which can further promote canopy protection and
enhancement.
Protect Trees During Development and Redevelopment — According to the USDA
Forest Service, it is estimated 175,000 acres of urban forest was lost per year between
2009 to 2014 due to development. During the same period, pavement and other
impervious surfaces grew by 167,000 acres each year (Janowiak et al. 2021). While
space is limited in urban areas, redevelopment projects do not have to result in the loss
of trees and tree canopy. By establishing tree protection measures and implementing
protection requirements whenever construction occurs near trees, the loss of valuable
canopy cover can be avoided. Further restrictions on development and/or acquisition
of land for the purpose of preservation and/or creation of conservation easements on
private land holdings can limit development and its effects on the urban forest.
Follow a Comprehensive Tree Planting and Replacement Plan — With a
comprehensive tree planting and replacement plans, the resources needed to plant
trees and establish trees can be more efficiently and strategically used to meet canopy
goals and to maximize potential benefits (i.e., planting large-stature trees where space
allows, prioritizing growth and expansion of canopy to address canopy distribution
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Urban Forest Resource 18
inequities, planting trees at optimal distance and direction from building to offset
carbon emissions from heating and cooling).
Routinely Maintain Trees — When all community trees are proactively and
systematically maintained on a cyclical basis, optimal tree health and condition are
more easily achieved, which contributes to tree longevity and maximal benefits.
Ensure Tree Care Meets Industry Standards — By ensuring that tree care is
conducted by ISA certified arborists and meets industry standards, tree health is
optimized. Improper pruning practices (e.g., “topping” or removing the tops of trees
and reducing large branches to stubs) can be extremely detrimental to tree health and
can lead to irreparable damage that can lead trees to be prematurely removed.
Establish and Use Irrigation to Combat Drought — All trees need water during times
of drought. Droughts are occurring more frequently and for longer periods, which
require planning to ensure that trees receive water during such periods. By installing
efficient drip irrigation systems that are separate from turf irrigation or where not
feasible, supplying water bags or scheduling hand watering trees will have some
assurance that trees will receive adequate water.
Plant Trees per Best Practices — By planting trees per best management practices
and post-planting care are followed trees have improved long-term outcomes, which
can reduce maintenance costs and maximize benefits.
Set and Follow Minimum Soil Volume Requirements when Planting — In the urban
environment, soil is one of the most critical environmental factors that contributes to
street tree health. Trees have extensive root systems that grow beyond the spread of
the canopy and can be more than 6.5 feet into the ground (Day et al. 2010). If a tree is
provided with an adequate amount of uncompacted soil, then the necessary water,
mineral, nutrient, and oxygen requirements are more likely met and it will have a
greater opportunity to grow for years to come and can reduce costs associated with
maintenance (pruning) and infrastructure damage caused by trunk buttress flare and
root expansion (Clark et al. 1997).
Build Wildlife Habitat and Corridors — Strategically plant and/or preserve trees and
tree canopy to connect with and/or bridge existing core canopy to promote ecosystem
functionality and biodiversity and create wildlife habitat and corridors for the
movement of birds, insects, and other animals.
Strategy 4: Sustain or restore fundamental ecological functions of urban ecosystems
Climate change is projected to have negative impacts on the environment and in many cases is
already. In urban environments, trees are a critical component of the ecosystem. Trees have
numerous properties that make them natural tools for mitigating the many of the effects of
climate change. By supporting trees, the health of urban ecosystems can be improved through
lessening environmental degradation and reducing physical and emotional health incidents.
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The key adaptation methods or approaches include:
Maintain or restore soils and nutrient cycling in urban areas.
Maintain or restore hydrologic processes in urban forests.
Restore or maintain fire in fire-adapted ecosystems.
The following are examples of how urban forest management can support urban ecosystems:
Sequester and Store Carbon — Trees sequester carbon throughout their lifetimes and
store it in woody biomass. These carbon sequestering capabilities suggest that urban
trees could be incorporated into overall greenhouse gas emission reduction and/or
storage strategies. To maximize such carbon sequestering benefits, trees should be
retained as long as possible and when they must be removed, to avoid the release of
carbon back into the atmosphere from decomposition, utilize the woody biomass in
the highest and best possible end-use to maximize carbon storage capacity.
Strategy 5: Reduce the impact of physical and biological stressors on urban forests.
Climate change presents many challenges to the health of trees, including variations in
precipitation and extreme temperature shifts. With these changes, many trees that were once
successful in a local area may no longer be suitable.
The key adaptation methods or approaches include:
Reduce impacts from extreme rainfall and enhance water infiltration and storage.
Reduce risk of damage from extreme storms and wind.
Reduce risk of damage from wildfire.
Maintain or improve the ability of forests to resist pests and pathogens.
Prevent invasive plant establishment and remove existing invasive species.
Manage herbivory to promote regeneration, growth, and form of desired species.
The following are examples of how urban forest management can reduce physical and biological
stressors on urban forests:
Establish and Maintain a GIS Based Tree Inventory— Comprehensive, GIS-based,
current inventory of all intensively managed public trees to guide management, with
mechanisms in place to keep data current and available for use.
Follow a Current and Comprehensive Urban Forest Master Plan — Having an urban
forest master plan provides long-term management goals for increasing community
safety and preserving and improving the health, value, and environmental benefits of
the urban forest and can even support efforts in response to climate change.
Monitor Tree Performance — The inventory indicates the condition of trees and is
used to identify underperforming or maladapted tree species. Trees are continually
monitored for the condition and test species anticipated to be adapted to the future
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Urban Forest Resource 20
climatic conditions are incorporated and monitored. Managers have a sense of species
that either should be continued or phased out over time.
Fully Staff and Adequately Fund Urban Forestry Programs — Establish stable funds
to cover the costs of proactive and reactive tree maintenance as well as staffing,
administration, and programming. Stable funds can allow for consistent staffing to
meet daily workloads and ensure access to necessary equipment and vehicles needed
so that the community receives a high level of service.
Assess and Promptly Address Urban Forest Risks — Large, mature trees may be
removed because they are perceived as a health or safety hazard, but the benefits
these trees provide take hundreds of years to replace. While it is true that wherever
trees are present, there is some potential risk to people and property, many of these
risks can be mitigated. In many instances, removal of entire trees can be avoided,
through proactive inspection and management.
Follow an Integrated Pest Management Program — Use of Integrated Pest
Management (IPM) protocols can effectively address pests and diseases (Wiseman and
Raupp, 2016).
Prepare for Wildfire — In recent years, wildfires have devastated many communities.
With prolonged periods of drought and a changing climate, wildfire is likely to continue
to be a threat to communities that neighbor the wildland urban interface. Developing
wildfire preparedness plans is not only important for establishing community wide
evacuation protocols, but also can assist in wildfire mitigation strategies.
Build Drought Tolerance — The tree species that make up the urban forest each have
different requirements and are best adapted to certain environments. Drought tolerant
and native trees are represented in the inventory to help managers minimize tree losses
during and following droughts.
Strategy 6: Enhance taxonomic, functional, and structural diversity.
With highly mobile populations, the spread of pests and pathogens that can negatively affect
tree and other plant health is an ever-growing concern. Pests and pathogens that are currently
devastating tree populations in one part of the country now, can easily immigrate to other areas.
Through enhancing species diversity and stratifying the age of tree populations, communities
can reduce the likelihood of severe losses in canopy from pests, pathogens, or other stressors
brought on by climate change.
The key adaptation methods or approaches include:
Enhance age class and structural diversity in forests.
Maintain or enhance diversity of native species.
Optimize and diversify tree species selection for multiple long-term benefits.
Maintain or enhance genetic diversity.
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The following are examples of how urban forest management can enhance taxonomic,
functional, and structural diversity:
Diversify the Population of Community Trees — Industry leaders suggest that no
species should represent more than 10% of a population and no genus should
represent more than 20% of a population (Clark et al. 1997; Santamour, 1990).
Managers should consider diversity (i.e., species, genera, and family) when planting new
and/or replacement trees to reduce vulnerabilities to pests and pathogens and reduce
the likelihood of catastrophic losses to trees and tree canopy (Janowiak et al. 2021).
Strive for an Ideal Aged Tree Population — An ideally aged tree resource allows
managers to allocate annual maintenance costs uniformly over many years and assures
continuity in overall tree canopy coverage and associated benefits. Striving to achieve
an ideal age distribution ensures that there is a high proportion of young trees planted
to offset establishment and age-related mortality as the percentage of older trees
declines over time (Richards, 1982/83).
Provide Adequate Funding and Resources for the Urban forest — The community
tree resource, just like other community infrastructure, requires consistent planning and
maintenance. Climate change is likely to increase the frequency of reactionary
maintenance. By providing stable funding for urban forestry, preventative maintenance
can occur, which is frequently less costly than reactive maintenance and prolong the
lifetimes of trees.
Strategy 7: Alter urban ecosystems toward new and expected conditions.
Research is actively trying to understand the potential impacts of climate change. With climate
change, local climate conditions are expected to shift. Models have been developed to project
some of these changes and communities can evaluate these projections and begin planting
trees that are anticipated to be more successful in future climatic conditions.
The key adaptation methods or approaches include:
Favor or restore non-invasive species that are expected to be adapted to future
conditions.
Establish or encourage new species mixes.
Introduced species, genotypes, and cultivars that are expected to be adapted to future
conditions.
Disfavor species that are distinctly maladapted.
Move at-risk species to more suitable locations.
Promptly revegetate and remediate sites after disturbance.
Realign severely altered systems toward future conditions.
The following are examples of how urban forest management can support urban ecosystems:
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Urban Forest Resource 22
Apply Climate Change Projections to Species Selection — Increasingly, cities are
recognizing that shifts in weather patterns are likely to alter species habitat ranges and
render some species less adapted to the region. Although there is no clear consensus
on the future outcomes, some research has pointed to looking toward comparable
cities thought to have a similar climate to future projections as a way to move forward.
The current climate of a comparable city is known (Bastin et al. 2019) and managers
make connections with colleagues in comparable cities and explore their species
palettes. Experimental species are chosen based on climate projections, such as
changes in temperature and precipitation. Strategies for climate adaptation include
favoring species that are predicted to do well in climate models, encouraging new
species mixes, and choosing species that are well adapted to weather events such as
flooding, high winds, and other storm events (Janowiak et al. 2021).
Remove and Replace Trees — Some species of trees are maladapted to the local
climate or succumb to pressures brought on by climate change (e.g., saltwater
intrusion, increased temperatures, etc.). Once species are identified to be unsuccessful,
future plantings of the species should halt and existing trees be gradually phased out
and removed.
Fully Stock the Community Tree Resource — Municipalities are limited to planting
trees in the public rights-of-way. If all vacant sites are tracked and as funding permits,
planted with trees, then the contribution of public trees to overall canopy cover is
maximized.
Strategy 8: Promote mental and social health in response to climate change.
Climate change is anticipated to severely impact human health and many health issues may
exacerbate inequalities and disproportionately affect those with underlying health conditions.
The key adaptation methods or approaches include:
Provide nature experiences to ease stress and support mental function.
Encourage community and social cohesion to support climate response.
The following are examples of how urban forest management can promote mental and social
health in response to climate change:
Share Information, Ideas, and Resources — Collaborative planning is important for
effective communication amongst partners to plan for and respond to climate change
stressors. Together, managers can communicate and collaborate to address the urban
forests’ greatest vulnerabilities and select experimental species that may be best
adapted to the future climate.
Integrate Urban Forestry in Climate Planning and Policy — Trees have properties
that make them especially useful in mitigating the effects of climate change. Wherever
possible, policies and long-term planning for response to climate change should
consider opportunities to support urban forestry programming.
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23 Urban Forest Resource
Strategy 9: Promote human health co-benefits in nature-based climate adaptation.
Nature-based climate adaptation technologies, like trees, can not only mitigate the effects of
climate change, but also promote improvements in human health.
The key adaptation methods or approaches include:
Co-design large-scale green infrastructure and build systems to promote health.
Provide micro-scale nature experience to promote health and healing.
The following are examples of how urban forest management can promote human health co-
benefits in nature-based climate adaptation:
Considered Trees Essential Infrastructure — Prior to planting a tree, provide
adequate space for future growth of the tree (including space for the root systems) and
consider future impacts of trees with lines of sight and other critical infrastructure and
to avoid conflicts between trees and above or below ground utilities. In many instances,
structural pruning can mitigate conflicts with infrastructure and avoid premature
removal.
Incorporate Trees into Stormwater and Other Green Infrastructure — Trees filter
stormwater, cleaning and moderating the amount of water in urban areas. Urban
forests can provide both cost savings and reduce pressures on engineered systems with
urban area function in mind.
Specific recommendations for the City of San Luis Obispo for implementing and improving
resiliency strategies are noted in the sections where they apply.
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Urban Forest Resource 24
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25 Operations and Programs
Operations and Programs
San Luis Obispo’s urban forest is composed of both public and private trees within City limits
and in the surrounding Open Space areas. Trees within the built environment, or in the
urbanized area, require more management than trees within the City’s Open Space areas and
other more natural areas. The Urban Forest Services program within the Department of Public
Works is responsible for the maintenance of trees along streets, in medians, parks, and at City
facilities. Urban Forest Services staff perform the following services:
Maintenance of trees along streets, in medians, parks, and at public facilities
Proactive maintenance of trees in the downtown core
Accelerating maintenance for grid pruning to re-establish a maintenance cycle
for all other rights of-way trees (contractor)
Reactive maintenance resulting from service requests or special requests (e.g.,
planting, pruning, watering) (in-house or contractor)
Contract monitoring (grid pruning, removal, stump grinding, and planting)
Commemorative Tree Program
Service requests/citizen complaint and correspondence
Safety and clearance for all public trees (including natural areas)
Safety and clearance for private property trees that interfere with public rights-of-way
Emergency response for all public trees
Tree inspections, including new tree plantings
Tree removal applications
Enforcing the Tree Ordinance
Development design review
Heritage tree program
Tree Committee liaison
Coordinating with urban forest partners
Community outreach and engagement
Addressing hardscape/tree conflicts
Supplemental watering
Pest monitoring
“The City should have an
aggressive street tree
planting and maintenance
program.”
-Survey Respondent
Page 525 of 748
Operations and Programs 26
Services and Programs
Service Requests
Residents can submit service requests and report
tree issues through a link on the City’s web page.
The Public Works Department also has a central
call line, but residents are directed to the online
portal when possible. Urban Forest Services
receives approximately 415 service requests each
year. Most service requests are for pruning to
address fallen or broken limbs or tree removal.
At any given time, there may be around 20 open
service requests. Generally, staff review requests
within 24-hours, but the time it takes to address
the request depends on the situation. For example,
downed limbs are typically addressed on the same
day whereas requests for tree removals require an
inspection, which can take as long as a week. If
approved, trees will be removed within the
scheduled cycle or a property owner may pay for the removal at their own expense. The majority
of requests for tree removals are attributed to conflicts between trees and sewer lines. Residents
Staffing Level Changes
Historically, the urban forestry program has provided proactive maintenance to all
community trees along streets, in parks, public rights-of-way, and at city facilities on an 8–
10-year cycle with an in-house tree crew. The team was fully staffed with 1 city arborist, 3
urban forest service staff, 3 tree assistants, 1 annual contract arborist, and 1 arborist in the
Community Development department who was responsible for design review.
Since 2019, staffing in the urban forestry program has dwindled. Attrition from retirements
and transitions has reduced staffing from 4 FTE staff members to 2. At current staffing
levels (2 full time staff), Urban Forestry Services is limited to providing reactive
maintenance for most community trees (excluding trees in the downtown core and
watering).
In an effort to return to previous service levels and catch up on delayed routine
maintenance, Urban Forest Services increased the use of contractors. Since the beginning
of 2021, Urban Forest Services is having contractors prioritize areas known to have higher
risk trees. San Luis Obispo is like many municipalities, where tree maintenance is
increasingly being contracted out to reduce risk and reduce the physical demands on City
staff. Despite staffing levels and a period of deferred maintenance, Urban Forest Services
staff exhibit extreme professionalism and are committed to identifying areas to make
progress on maintenance priorities and fulfill the responsibilities for the care of
“I appreciate how quickly a SLO
urban forest employee
responded when we had an issue
with a tree on the sidewalk near
the driveway to our house
(large, broken branch was
hanging so low that we couldn't
access our driveway without
possible damage to our cars).”
-Survey Respondent
Page 526 of 748
27 Operations and Programs
with old, cracked sewer pipes often experience issues when tree roots exploit cracks in search of
water. Urban Forest Services requires images or video of the damage before approval of a
removal request for any healthy tree that has roots growing into sewage pipes. As the City is
concerned with stormwater intrusion, there is a voluntary program for sewer line replacement
through the utilities program. This program allocates a set amount of funding to address this
issue in specific districts that tend to experience the majority of cracked sewer pipes.
Tree Pruning
Urban Forest Services program’s primary objective is to maintain the estimated 20,000 trees
along streets, in parks, rights-of-way, and at public facilities on an 8 to10-year pruning cycle, but
maintenance currently is largely reactive and staff estimates they are a full cycle behind (8 to10
years behind in maintenance). The Urban Forest Services program has contracted tree pruners
working to accelerate maintenance work to get back to a regular pruning cycle. With the current
maintenance backlog, inspections for trees only occur during routine maintenance or when staff
are in the field. Ideally, Urban Forest Services would conduct proactive, cycle-based maintenance
that corresponds to the maintenance schedule for other Public Works assets. The intent of these
studies and inventories is to provide the necessary resources to the program to properly
management the urban forest assets to the community’s expectations.
While the frequency of care and the levels of services have been reduced in most areas of the
community, downtown trees receive biannual maintenance for structural pruning, building
clearance, and signage visibility. Business owners are notified of pending work whereas residents
are notified of this and all other maintenance through parking notices. If adjacent property
owners wish to prune a tree outside of the Urban Forest Service’s maintenance schedule, the
resident must first acquire permit and must employ an ISA Certified Arborist to perform the
work.
Recommendations for UFSP Planning: Service Requests
Clearly communicate which services Urban Forestry Services offers and the time it
takes to provide the services in a future urban forest strategic plan.
Challenges and Opportunities: Service Requests
Some community members use the hotline to call in situations that are out of the
scope of services, taking up valuable time and resources.
Service requests are submitted frequently because the majority of street trees
adjacent to private property are not regularly maintained.
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Operations and Programs 28
Municipal Code 12.24.150 protects all trees within the City from improper pruning practices by
requiring that all tree care follow industry standards. The primary focus for pruning may differ
between city departments (e.g., safety, risk management, storm mitigation, utility clearance), but
following industry standards ensures that all public trees are properly maintained. Stakeholders
indicated some concern for tree pruning that occurs in natural areas where the primary focus is
on quickly addressing safety and clearance issues. A future UFSP should reiterate the
requirement to follow industry standards for all tree care and ensure that maintenance staff are
fully trained to meet these requirements. When private trees are damaged due to improper
pruning, the Urban Forest Services Program enforces the City’s Municipal Code and holds the
responsible parties responsible for violations. Despite this, not all trees are receiving quality care.
Challenges and Opportunities: Tree Pruning
The pruning cycle is estimated to be one full cycle behind.
Resources need to be augmented to meet community and organizational needs.
Industry standards recommend trees be pruned on a 5 to 7-year cycle, but current
maintenance is reactionary.
Despite Municipal Code, maintenance on some trees does not follow industry
standards including private property and natural areas where the primary focus is on
safety and clearance.
Inspections occur during the routine maintenance of trees in the downtown core, but
most trees are not regularly inspected.
All City trees should receive the appropriate maintenance complying with best
management practices.
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29 Operations and Programs
Recommendations for UFSP Planning; Tree Pruning
Use maintenance schedules to quantify resource needs for budget augmentation.
Continue to use contract services to enhanced tree pruning and maintenance to
promote the long-term health and vigor of the city's urban forest, as well as maintain
public safety (per Strategic Budget Direction Report).
Determine the amount of funding needed to maintain a fully stocked inventory,
where all planting sites are filled.
Ensure contract services are regularly evaluated to ensure work meets best
management practices and standards.
Ensure all public trees are maintained according to industry standards as well as
Municipal Code.
Move toward a 5-year maintenance cycle to proactively maintain all rights-of-
way trees using pruning grids to efficiently group routine maintenance.
○ Publish the grid pruning map and schedule on the City website to
provide residents with information on when to expect routine service.
Continue to plan for the increased maintenance for species that require more
frequent pruning in the downtown area as well as throughout the community
(an estimated 20% of the current inventory).
Work with the Parks and Recreation Department to ensure proper pruning for
trees in natural areas.
Develop an annual work program (per Management and Performance Audit of the
Public Works Department).
Use Department-wide work planning and scheduling systems.
Include tree planting and maintenance costs for trees planted in support the
goal of planting 10,000 new trees by 2035 in partnership with ECOSLO and
the community (per Strategic Budget Direction Report).
Provide efficient and prescriptive maintenance to all city trees.
Continue to work with Downtown SLO Ambassadors and the Downtown Foresters
for tree well maintenance and tree pruning in the downtown core.
Designate someone qualified within Urban Forest Services to set the level standards
and policies for tree care.
Communicate the standards to all other City departments and partnering
organizations tasked with managing public trees.
Lead a campaign to support business licensing for tree care professionals and to
educate private property owners on their responsibilities.
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Operations and Programs 30
Clearance and Visibility
Urban Forest Services provides clearance and visibility pruning for all trees interfering with the
public rights-of-way. In the past, Urban Forest Services commonly provided safety and clearance
services to private trees interfering with public property. This is an auxiliary service that takes
away time and resources that should be directed toward the care of public trees because
Municipal Code designates private property owners responsible for addressing safety concerns
on their property. While the goal is to change this precedent, staff continue to provide safety
and clearance services to private trees for increased safety and accessibility. Municipal Code calls
for Urban Forest Services to provide a notice to property owners to abate clearance and visibility
issues caused by privately-owned vegetation encroaching into the rights-of-way.
Heritage Trees
Heritage trees are landmark trees that stand out for their size, growth habit, or represent a
unique species. Trees can be nominated for this designation by anyone in the community, but
trees must be approved by the Tree Committee and City Council before they are given this
designation and recognition. Once a tree becomes a heritage tree it is given the highest
preservation priority. According to Municipal Code, heritage trees can be any healthy tree within
City limits and the City is responsible for their maintenance. The current Urban Forest Services
policy is to inventory heritage trees, but designate maintenance responsibilities to the property
owner.
Urban Forest Services provides information about the heritage tree program for the City website
and features a self-guided tour of San Luis Obispo’s heritage trees, which includes the tree
location, photos, notable facts, and relevant history.
Challenges and Opportunities: Clearance and Visibility
Urban Forest Services is upholding the past precedent to provide safety and clearance
services to private trees.
Heritage Trees
There is a discrepancy between the Municipal Code and the current Urban Forest
Services policy around the maintenance of heritage trees.
Recommendations for UFSP Planning: Clearance and Visibility
Increase public awareness of Municipal Code that designates private owners as
responsible for private tree clearance and safety concerns.
Heritage Trees
Modify Chapter 12.14.160 Heritage Trees to designate private property owners
responsible for their maintenance.
Consider a permit process to prune heritage trees.
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31 Operations and Programs
Tree Planting
Urban Forest Service’s tree planting efforts are primarily grant based and conducted by the
longstanding nonprofit partner organization ECOSLO or contractors. Urban Forest Services does
not have an up-to-date inventory that includes available planting sites (i.e., stumps and vacant
sites) nor a tree planting and replacement plan. Staff direct tree planting to known vacant sites,
but with these tools, tree planting could be done in a more targeted, efficient manner. On
average, approximately 150-200 new trees are planted each year in vacant sites within public
rights-of-way and Public Works is responsible for planting approximately 50 trees each year and
relies on partnering organizations to plant the remainder. Urban Forest Services provides young
tree care to trees they plant, including watering. Mortality rates are generally low (<5%) and are
mostly attributed to gopher damage, lack of establishment, or vandalism.
ECOSLO is co-leading the City’s tree-planting efforts in
the rights-of-way. ECOSLO and its volunteers have been
integral to obtaining grant funding, planting, and
establishment of 140 new trees since 2019. The
organization works with several city departments,
including Urban Forest Services, to identify planting sites
and flag utility lines. For tree-planting requests in front
of private property, ECOSLO encourages residents to
choose a species from a limited list, based on the
approved street tree list, grant requirements, and current availability. Planting is done by hand,
which is difficult due to the hard, heavy clay soil. This is becoming a limiting factor for the
organization because only a portion of volunteers are able to help with the physically
demanding tree plantings. The City also relies on ECOSLO for watering and providing some
structural pruning on the young trees planted through the partnership (during the first three
years).
All tree planting on public property follows the City’s Tree Planting Standards as well as the
Guidelines Specifications for Nursery Tree Quality, which is a document compiled by industry
professionals in the region. Nursery stock is monitored to ensure newly-planted nursery trees
are of high quality and to ensure any existing structural problems are identified and addressed
as quickly as possible (e.g., problematic branch connections or girdling roots).
“Tree planting requires continuous community engagement, volunteerism, and
stewardship beyond what our small City Urban Forest Services team can
provide.”
-Survey Respondent
“ECOSLO is a relatively
small nonprofit trying to do
BIG work.”
- Executive Director,
ECOSLO
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Operations and Programs 32
Community members are interested in caring for and expanding the urban forest. As a
testament to this, community members initiated 10 Tall: An Initiative to Plant 10,000 Trees on
Public Property in San Luis Obispo by 2035, which was introduced in the Climate Action Plan.
Planting efforts are largely centered around low-cost, one-gallon container stock of native trees
in City open space, creeks, and riparian areas. However, a subset of the 10,000 trees will be
larger container trees and fill in vacant tree wells. This initiative is currently in the visionary stage,
and Urban Forestry Services and ECOSLO are currently assessing their capacity to meet this
vision. Public Works is aligning staffing and funding levels with this vision, as they will ultimately
be responsible for the planting and maintenance of trees in the public-rights-of way.
In the benchmark community survey, eleven participants
expressed the importance of tree planting and increased
tree canopy at schools. While school properties present
an opportunity for potential planting space, the San Luis
Coastal Unified School District has been reluctant to
expand existing tree planting efforts at facilities. Urban
forest partners believe the barriers to tree planting at
local schools are related to their capacity to provide tree
maintenance and limited species availability through
grant funded tree planting initiatives.
“Please look at our public
school's needs for trees.
Many of the school sites in
SLO can benefit from
more trees.”
-Survey Respondent
Environmental Center of San Luis Obispo (ECOSLO)
The nonprofit ECOSLO has been working to preserve and protect the beautiful natural
areas of San Luis Obispo for more than 50 years. Since the organization’s humble
beginnings as a group of college students taking it upon themselves to clean up city
creeks, it has grown into being the area’s premier nonprofit for environmental advocacy.
Among residents, ECOSLO may be most well-known for its creek-to-coast clean-ups, which
historically have had considerable volunteer support and turnout. However, ECOSLO now
works across many facets, including open space stewardship, county parks, green business
development, sustainability outreach, and as of recently, urban forestry. Currently, ECOSLO
is a team of six with two staff members primarily dedicated to the urban tree program.
These staff members coordinate with numerous partners and, at any given time, work with
approximately 40 volunteers.
ECOSLO is an incredibly valuable partner to the City, who has come to rely on ECOSLO for
several projects, including trail work and tree planting. In 2019 a grant with California
ReLeaf spurred what is now a large focus for the organization, planting trees in the urban
areas of the community. Currently, ECOSLO is managing three tree planting projects
supported by CAL FIRE, the Tourism Business Improvement District Board, and Hardwood
Revitalization. In addition, the city has already relied heavily on ECOSLO in their robust tree
planting initiative. The natural areas and features of San Luis Obispo, so intensely treasured
by residents and visitors alike, would not be what it is today with ECOSLO! The partnership
between ECOSLO and the City of San Luis Obispo is a model example for progressive tree
planting partnerships.
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33 Operations and Programs
Commemorative Tree Program
The Commemorative Tree Program, managed by the Public Works Department, allows residents
and groups to plant a tree in the Commemorative Grove at Laguna Lake Park in honor of
significant events or people. In the past, the Urban Forest Services provided planting,
maintenance, and replacement trees for those that were damaged or removed. Although not the
City’s responsibility, plaques are often damaged, vandalized, or removed. While the City has
long prided itself on offering this service, the program has been temporarily suspended due to
the COVID-19 pandemic and other recent complications. Maintaining the Commemorative
Grove is time-consuming and with the program's suspension, there is a considerable
maintenance backlog. The City is currently assessing how to manage the program.
Challenges and Opportunities: Tree Planting
A City-wide tree planting and replacement plan does not exist.
Vacant tree wells are common and hard to locate because inventory records are not
up-to-date.
Existing stumps limit planting in available spaces.
Replanting does not occur quickly.
ECOSLO staff have informal training on tree care and rely on community partners for
technical advice.
Most young trees are not pruned by Urban Forest Services for the first 5-6 years.
ECOSLO is limited in the number of trees they are able to plant.
ECOSLO does not have heavy machinery such as a truck, watering truck, or
auger, therefore tree planting is done manually.
ECOSLO would have a greater capacity to plant trees if holes were pre-drilled.
Due to visibility and safety concerns for volunteers, the ability to plant trees in
medians is limited.
Tree planting does not occur at local schools.
Commemorative Tree Program
Many trees have suffered as a result of recent droughts and replacing them has been
a challenge.
The Commemorative Grove initiates a relatively high amount of service requests for
trees that die, as each tree is tied to an individual or event.
Plaques were installed on the ground, which presents difficulties maintaining grass
and controlling weeds.
The costs of maintaining the Commemorative Grove are not adequately covered by
the current fee structure, as the fees only cover the planting cost.
The current location of the Commemorative Grove hinders some functionality of the
park.
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Operations and Programs 34
Recommendations for UFSP Planning: Tree Planting
Create a planting plan.
Identify tree planting sites (per Strategic Budget Direction Report and
Climate Action Plan).
Include the number of trees that need to be planted by Urban Forest
Services, ECOSLO, as well as other partners (e.g., Tourism Business
Improvement District Board) and Departments each year to support the
initiative to plant 10,000 new trees.
Plan for the increased planting and maintenance efforts that will be taken on
by Urban Forest Services as a result of the 10,000 Tree initiative.
Quickly replant rights-of-way trees and replace infrastructure damaged by tree
roots upon tree removal (not only those in wells).
Set and follow policies to check that replacement plantings occur after removals.
Ensure young trees receive structural pruning several times in the first 5-6 years to
meet industry standards.
Include shade trees as a cooling mechanism in new development (per Urban Heat
Effects Policy in the General Plan).
Engage with ECOSLO in strategic planning to determine what each party can
manage in regard to future tree planting.
Consider pre-drilling holes with an auger for ECOSLO plantings or donating
equipment for this use.
Take over tree planting in medians, as Urban Forest Services can follow clear safety
policies set by the City and the materials needed to divert traffic.
In the planning process, explore ways to partner with schools to increase canopy
cover.
Address schools’ concerns over maintenance with possible solutions.
Commemorative Tree Program
Re-evaluate the program, consider ways to continue recognizing and memorializing
significant individuals while addressing maintenance challenges.
Consider implementing a commemorative wall, bravado, and/or path with
engraved bricks as memorials so that a tree is not tied to an individual.
Work with the community and other City departments to determine if another
location would be more appropriate for the Commemorative Tree Grove.
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35 Operations and Programs
Tree Selection
The City has a regularly updated (every
4-5 years) Street Trees Species List in the
Engineering Standards that guides tree
species selection. Urban Forest Services
is interested in expanding the tree list.
Local nurseries stock an assortment of
species, but on occasion, some species
are not available. Other species perform
well in San Luis Obispo, but they are hard to source and therefore are not widely planted.
Right Tree, Right Place
To visitors and residents alike, the most recognizable trees in San Luis Obispo are the large
ficus trees that line the streets of downtown. Many people have a fondness for these trees,
as the urban forest is part of the culture in San Luis Obispo and these particular trees have
been an integral part of downtown for around 50 years. These trees provide ample shade
to the downtown area of San Luis Obispo, and undoubtedly contribute other benefits.
While it is always unfortunate when one of these iconic ficus are removed, practicing
“Right Tree, Right Place” can help avoid some of the current issues caused by the trees.
The practice of installing the optimal species for a particular planting site is known as the
“Right Tree, Right Place”. This philosophy considers the effects of tree growth on existing
and planned utilities, existing landscape, and other infrastructure. Factors to consider
include, planter size, soil characteristics, water needs, as well as the intended role and
characteristics of the species. By considering the long-term consequences of planting a
particular tree in a particular place, conflicts and premature removal of trees can be
avoided.
Some species, such as redwoods, are not suited for the local climate and climate change
will likely exacerbate the problem. In the case of the downtown ficus trees, there are
several causes of concern when considering “Right Tree, Right Place.” First, the ficus tree
population is in a state of decline due to aging, which increases maintenance costs, safety
concerns, the incidence of nuisance pests, and disease potential. Due to the large size of
the trees and the root systems, sidewalk buckling and safety are ongoing issues.
Furthermore, ficus trees drop fruit, which requires clean up, can cause slipping hazards,
and commonly attracts flies and pigeons.
Ficus trees are also largely a monoculture in the downtown area, and species diversity is an
important aspect and goal for the urban forest going forward. This is not to disregard their
importance and relevance to the San Luis Obispo urban forest. Urban Forest Services is
slowly replacing ficus with other species, aligning with the philosophy of “Right Tree, Right
Place.” Going forward, replacement and new plantings should consider different species to
increase species diversity and age distribution.
“I definitely would plant more trees in
my front and back yard if I know what
and where!”
-Survey Respondent
Page 535 of 748
Operations and Programs 36
Challenges and Opportunities: Tree Selection
The species list should be expanded to include climate ready species.
Species availability is dependent upon current nursery stock and some species the
City, ECOSLO, community members, or grant funders want to plant are not available
through vendors.
Some species are performing well, yet they are not widely planted.
Some species are not considered in future plantings because people rule out
species because they are basing their opinions on the maintenance needs of overly
mature individual trees.
Planting the appropriate tree species for the available space to help to reduce
infrastructure conflicts and nuisance fruit drop (“Right Tree, Right Place”).
Providing ample shade downtown by selecting adequate replacement species
during the phased removal of downtown ficus trees.
Community survey respondents expressed a desire to incorporate more trees
known to support wildlife.
There is some desire to increase the amount of fruit and bearing trees in the
community along pedestrian and bike paths and parks.
While fruit trees could provide residents with a nutritious source of food,
consider the maintenance requirements associated with fruit and nut
producing trees.
○ Increased maintenance to clean-up of fruits and nuts.
○ Potential to harbor agriculturally significant pests and pathogens.
Determine if trees will be pruned for fruit production.
Determine who is able to harvest fruit from public trees.
Some trees are blocking historic and architecturally significant buildings.
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37 Operations and Programs
Irrigation
Trees in the public rights-of-way are rainfed and hand-watered when needed by staff with a
City-owned water tanker. Through ECOSLO’s Adopt-a-Tree Program, called Tree Keeper,
volunteers’ water their adopted tree using a 5-gallon water jug. Trees are watered with 5-10
gallons of water each week. ECOSLO and the City have an agreement where volunteers are
permitted to access public water at the City’s Corporate Yard (non-potable well), at parks, or
community gardens. Other strategies such as water bags, mulching, and informal neighbor
adoption also provide water to rights-of-way trees. Urban Forest Services requests irrigation
systems be retrofitted in a limited number of locations with a significant amount of landscaping
impacted by redevelopment projects.
Trees in parks are irrigated with lawns on a watering schedule that is also conducive for the
trees. Per the General Plan, recycled water is used to irrigate park trees whenever possible. The
recycled water often has high levels of salt and chlorine, although park trees are not currently
experiencing problems. The San Luis Obispo Water Resource Recovery Facility is transitioning
the use of UV filtration technology and this problem will be resolved. It is likely more parks can
be transitioned to recycled water as distribution lines are implemented.
Recommendations for UFSP Planning: Tree Selection
Expand the tree list.
Engage the Tree Committee and Cal Poly students when doing so.
Work with vendors, and collaborators such as Cal Poly, to get access to
species that are not currently available.
Consider limiting the incorporation of tree species that require more
frequent maintenance.
Develop specific planting plans and palette themes for neighborhoods and areas
with different characteristics.
Engage the community in meetings to determine preferences for a
downtown tree list and age succession of downtown trees.
Identify and implement a strategy for a prioritized replacement schedule for
downtown ficus trees in order to ensure the long-term preservation of the street
tree canopy (per Strategic Budget Direction Report).
Explore the use of plant growth regulators to decrease maintenance needs of
downtown ficus.
Consider conducting case studies on other communities using growth
regulators.
Explore the use of anti-gibberellins to reduce nuisance berry drop.
Promote species that provide wildlife habitat.
Page 537 of 748
Operations and Programs 38
Challenges and Opportunities: Irrigation
Irrigation is not in place for current trees nor is there a plan for irrigation for new
trees planted as part of the 10,000 Tree initiative.
Changing water needs as a result of climate change and significant new tree
plantings.
Watering needs fluctuate and it is difficult to predict how much of Urban Forest
Services staff’s time will be needed to water in any given year.
ECOSLO has to frequently remind volunteers and City staff about their agreement
for volunteers to access city water at parks and community gardens.
Vigilant community gardeners are unaware of the agreement ECOSLO and the City
have to access city water. This negatively reflects on the program and can be
difficult for ECOSLO volunteers to navigate.
Recommendations for UFSP Planning: Irrigation
Update the engineering standards to require irrigation in new tree plantings.
Create an irrigation installation standard for the 10,000 Tree initiative.
Include requirements for developers or property owners.
Work collaboratively with the San Luis Obispo Water Resource Recovery Facility to
implement irrigation whenever feasible.
During new and re-development.
During street renovations.
As new lines are implemented.
Consider taking on some of the responsibilities to ensure newly planted trees in the
rights-of-way are adequately watered.
As the water facility is upgraded, include tree irrigation as part of this plan.
Explore additional planter designs to help with stormwater management and
bioremediation.
Explore improvements to the watering agreement with ECOSLO.
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39 Operations and Programs
Tree Removal
Although there are some exceptions, tree removal is regulated for the majority of otherwise
healthy trees within the City. Municipal Code 12.24.090 prohibits removing most any tree (public
and private land) without a permit and requires replacement trees to mitigate the loss of
canopy. Residents can submit a service request for the removal of dead or dying public trees.
Trees are inspected and if a tree needs to be removed, the tree will be removed during the
routine maintenance schedule, if it does not constitute a public hazard. Residents may pay for a
tree to be removed outside of the schedule. On average, less than 50 community tree removals
occur each year.
Per Municipal Code, all tree care
companies are required to be licensed.
Yet, some tree care companies are
operating without licenses and
participate in illegal removals. Urban
Forest Services is responsible for the
enforcement of the Tree Ordinance and
is authorized to hold both the private
property owner and the vendor
responsible for violations of the chapter
(including illegal removals). Many
violations are reported by neighbors. All responsible parties are subject to fines and must
mitigate the loss of the tree or trees through a mitigation plan.
Mitigation planting, as a result of the removal of rights-of-way trees, can be a slow process. For
the relatively small portion of community trees removed from wells, City staff are responsible for
mitigation planting and trees are replaced relatively quickly. All other mitigation planting is
performed by contractors or ECOSLO. The City always meets, but more typically exceeds, the
current mitigation for replacement by planting more trees than are required. In mitigation
Illegal tree removals are most commonly spotted and called in by neighbors. Even so, collecting
evidence and accessing policies make mitigation challenging. Many community members are
concerned that a large portion of mitigation plantings on private property do not occur at all.
Also, some residents are reluctant to plant trees because Municipal Code requires mitigation
planting upon removal. The City should educate the community about the options to plant for
mitigation.
Tree Removal Applications are required for the removal of private trees. The City Arborist will
review requests for removals and inspect trees and either approve or deny the removal request.
Residents and developers can appeal the City Arborist’s decision to the Tree Committee or
Community Development Director (Figure 4). Community members can review pending removal
permits on the City website and may submit an appeal within 10 days. Approximately 25% of the
City Arborists decisions on tree removal permits are appealed.
“The city requires a property owner to
get permission to remove a tree, requires
replacement planting, but never checks
to see that the replacement planting has
taken place.”
-Survey Respondent
Page 539 of 748
Operations and Programs 40
Figure 4: Tree Removal Flow Chart
In 2019, the Municipal Code was amended, which provided the Urban Forest Services and the
Tree Committee with improved standards to review tree removal requests. Some subjectivity
remains in the ordinance, but staff try to remain consistent in decisions for approval or denial of
removal requests. The recent revisions improved the tree removal application process and Urban
Forest Services is actively working to educate and assist residents and developers with these
changes.
After removal, Urban Forest Services hires contractors for stump grinding. Occasionally,
contractors have not ground stumps adequately, which prohibits replacement planting until it
has been re-ground. To address this, the City recently modified their contract to include
guidelines that ensure stumps are ground to an adequate depth and to prepare the site for
future planting.
Debris and Wood Utilization
When public trees are removed, either the contractor disposes of the material or the in-house
crew chips and repurposes the woody material into mulch. Mulch is used in parks or is offered
to residents for private use. Residents can pick up mulch at designated public pick-up sites
seven days a week. These sites are the City Corporation Yard, Laguna Lake, and Sinsheimer Park.
Page 540 of 748
41 Operations and Programs
To save on disposal costs and to give the community an opportunity to use wood produce from
urban forestry operations, Urban Forest Services will occasionally leave usable wood adjacent to
the rights-of-way, where residents can take the wood on a first-come, first-served basis. Until
recently, a local mill that specialized in reclaimed wood processed wood from in-house
removals. The wood produced from this operation was used to make custom furniture.
ECOSLO received the Hardwood Revitalization Grant, a CAL FIRE grant focused on planting trees
that have an end-use for furniture. Likely, these trees will be harvested before they are mature,
between 20 to 50 years from now. ECOSLO is responsible for their establishment and then these
trees will become the Public Works Department’s responsibility. The City realizes that premature
removals may become contentious, as community members have a strong desire to see healthy
trees maintained to the end of their lifespan. In addition, trees removed as part of the Hardwood
Revitalization Grant will require milling rather than chipping, which is a different process than
other rights-of-way trees.
Challenges and Opportunities: Tree Removal
In the past, Urban Forest Services has not always followed the Tree Ordinance when
approving tree removal permits.
Current staff are doing their best to follow these policies and provide clear
documentation on their rationale, but there is still confusion for those applying for
tree removal permits.
Applicants or property owners call City staff regarding permit applications. These staff
do not have access to information to update callers if the tree(s) in question have
been approved or appealed.
There is little to no code enforcement so many tree replacements that result from
tree removals do not get planted and it can be hard to track down those involved in
illegal tree removals.
There is some subjectivity in Municipal Code 12.24.090, convoluting the process for
tree removals, especially as to what constitutes as significant damage to
infrastructure.
Current policies allow for mitigation planting to occur offsite (another property or in
the rights-of-way), but an alternative Tree Fund does not exist.
Not all property owners understand the tree removal and mitigation planting process.
Public outcry commonly occurs around tree removals, especially large mature trees in
the downtown area and as a result of development projects.
Debris and Wood Utilization
There is no plan in place for the removal of trees planted as part of the Hardwood
Revitalization Grant through ECOSLO.
A wood utilization program is not in place.
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Operations and Programs 42
Recommendations for UFSP Planning: Tree Removal
Review and revise the ordinance to clarify what constitutes significant damage.
Conduct a PSA to promote proper tree care and business licensing within the City.
Consider testimonials from property owners.
Use a variety of outlets such as newspapers, social media, and the City’s
website.
Continue to consistently enforce Municipal Code when illegal tree removals occur.
Increase mitigation requirements in cases where large stature, mature trees are
being removed to incentivize retaining existing canopy. Explore alternative
mitigation measures, such as funds to increase the size of the greenbelt.
Have a system in place so partnering City staff can be up-to-date on information
when applicants or owners call regarding if the tree(s) in question have been
approved or appealed.
Follow up to ensure tree replacement planting / mitigation is occurring.
Explore creating a separate category on the City’s Tree Removal Application for tree
removals associated with biofiltration planters.
Explore creating a Tree Fund where mitigation fees as an alternative to tree
planting.
Explore an educational campaign outlining the City’s tree removal and planting
policies.
Debris and Wood Utilization
Coordinate with ECOSLO to determine ways to meet the Hardwood Revitalization
Grant requirements while addressing concerns about premature removals.
Consider outreach events to educate the community on wood utilization.
Consider the phased removal of trees planted as part of the grant so their
benefits are not all lost in a short amount of time.
Consider implementing a wood utilization program to help meet carbon
sequestration goals in the Climate Action Plan.
Collaborate with other City Departments and local mills.
Partner with contracting arborists to recycle/reuse wood from large tree
removals.
Track carbon sequestration benefits provided by community trees in the
urban areas.
Consider partnerships with local mills.
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43 Operations and Programs
Emergency Response
Urban Forest Services plays a significant role in the Public Works Storm Response Plan. Staff are
involved in training and implementing the storm response plan each fall prior to the rainy
season. The storm response plan has thresholds to activate departments. Urban Forest Services
staff have a clear understanding of when to respond, where equipment is stored, and identified
locations to stage debris.
When emergencies occur, Public Works, Parks and Recreation, Natural Resources have a
reciprocal relationship and help each other address tree maintenance across the community. All
crews help address emergencies such as storm cleanup and patrol along streets, in parks, and
open spaces although Rangers are relied on more heavily and take more responsibility. If Urban
Forest Services is not able to address a call, Ranger Services seamlessly steps in. In addition,
Urban Forest Services rely on contracted crews for quick response.
Community Engagement and Outreach
The City’s website provides quick and accurate information for residents on tree care operations,
current tree ordinance, the tree removal process, tree species selection, and frequently asked
questions. By partnering with ECOSLO, the City is able to incorporate educational materials
about the benefits of trees, the state of the urban forest, how to best care for trees, and how to
volunteer which provides another avenue for community support of the urban forest.
Urban Forest Services perform outreach with local elementary schools highlighting the benefits
of trees. They also hold an annual Arbor Day celebration that commonly includes tree talks by
City staff, tree plantings by ECOSLO and the public, and a tree art contest for elementary school
students in San Luis Obispo. Urban Forest Services had a bi-yearly presence at the Farmer’s
Market, both the week of Arbor Day and Public Works Week, where the booth for the urban
forest program is always one of the most popular. Some community engagement has been put
on hold due to the COVID-19 pandemic.
Challenges and Opportunities: Emergency Response
Currently, there is not a specific training program or drill for emergency response
duties.
Recommendations for UFSP Planning: Emergency Response
Implement a training program or drill that covers staff responsibilities during
emergency response.
Include existing emergency response policies in the future Urban Forest Strategic
Plan.
Page 543 of 748
Operations and Programs 44
As part of their tree planting partnership with the City,
ECOSLO coordinates an adopt-a-tree program called Tree
Keeper and engages a steady volunteer base. Volunteers
are typically enthusiastic to help plant and maintain trees,
demonstrated by their current volunteer base, exceeding
their need for current work. In fact, some trees are
receiving double watering in order to keep volunteers
engaged.
Cal Poly students make up a significant portion of the
volunteer base. In the past, Cal Poly students have interned
with the urban forest program, most commonly to conduct spot inventories. With an engaged
community, there is an opportunity to engage an even larger volunteer base for urban forestry
in San Luis Obispo.
Challenges and Opportunities: Community Engagement and Outreach
Partnering organizations have expressed interest in increasing collaborative efforts
to provide urban forest-related outreach and education as well as career
development internships within Urban Forest Services.
There is an opportunity to expand education and outreach at local schools.
Community members are interested in volunteering and the online survey results
revealed a potential to engage an untapped volunteer base.
Community members filled out the online survey in great numbers and many want
to be more engaged in the urban forest planning process.
There is an opportunity to partner with the Parks and Recreation Department in
facilitating urban forest outreach and volunteer events.
“My children's school
participated in an Arbor
Day art contest and tree
planting event.”
-Survey Respondent
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45 Operations and Programs
Development
Historically, a design review arborist was on staff in the Community Development Department.
The design review arborist was engaged in every development proposal. This position no longer
exists. Municipal Code requires developers to submit an arborist report with development
proposals, but proposals for single-family residential sites are up to the discretion of the
Community Development Department. If an arborist report is required, ideally, they are reviewed
by the City arborist for accuracy. Due to staff attrition, a fraction of the proposals is currently
being reviewed thoroughly by an arborist. This, coupled with the recent increase in growth/infill
Recommendations for UFSP Planning: Community Engagement and Outreach
Engage local schools.
Promote the benefits of the tree canopy in regard to student health and
well-being and provide access to the wealth of information that support
these benefits.
Develop tree care programs that students can get involved in, use tree
planting as an educational tool for students.
Work with ECOSLO to further circulate outreach and educational materials as well
as volunteer opportunities.
Promote the Adopt-a-Street-Tree volunteer program coordinated by ECOSLO.
Continue to partner with local nonprofit and tree advocacy groups to support tree
planting events.
Continue to collaborate with Cal Poly to provide students with environmentally
focused volunteer and internship opportunities.
Consider creating an annual internship with an arborist.
Collaborate with Downtown SLO to provide outreach and educational
programming around trees and the natural environment in the downtown area.
Provide nonprofit partners with more clarity on the communication chain and what
services are provided.
Continue to explore ways to engage ECOSLO’s volunteer base and expand
volunteer engagement.
Provide additional opportunities for engagement during the Urban Forest Strategic
Plan development process.
Organize another, more in-depth community survey.
Consider pop-ups at parks or local events.
Explore support for moving large urban forestry-related events and volunteer
coordination to the Parks and Recreation Department.
Page 545 of 748
Operations and Programs 46
development within the community, has led to many projects going without adequate
consideration for existing trees. As a result, many large, mature trees are being removed for
development projects. While replacement trees are required, they take decades to replace the
benefits and the community is currently experiencing a loss in tree canopy.
Currently, developers are responsible for maintaining new tree plantings in the rights-of-way for
1 year and then these trees become the responsibility of Urban Forest Services. While many of
these trees are in adequate condition, some trees were neglected and the City is responsible for
these poorly established trees. The City should consider prolonging developer maintenance of
new tree plantings to ensure proper establishment (e.g., 3-5 years) and mitigation if trees die.
State Housing Mandates
Historically, the City of San Luis Obispo has had a 1% growth rate cap set forth in the
General Plan Land Use Element (Chapter 17.144 of Municipal Code). According to the
City’s “Sustainable Growth Management” document, the last time this cap was reached
was 2004. Since then, growth has remained under 1%, hovering around 0.5% from 2015-
2020 (SLO City, n.d.). However, growth increased to 1.2% in 2021 and this growth trend is
expected to continue with an increasing population and multiple new development
projects in the City (Johnson, 2021). Starting as early as next year, the new State Housing
Bills have potential to compound this growth as they modify single-family zoning to
easier allow subdivisions and multi-unit properties.
In September 2021, several new bills were signed into law by Gavin Newsom to address
the growing housing crisis in California. The most consequential of them may be Senate
Bill 9, which changes single family zoning to allow for subdivisions and multiple units on
single-family zoned property. These bills aim to address a severe housing shortage and
demand for affordable housing across the state.
Senate Bill 8- extends the existing 2025 deadline for the ‘Housing Crisis Act of
2019’ by another 5 years, which requires local governments to increase density in
areas to offset ‘downzoning’ in other areas.
Senate Bill 9- will allow most homeowners to build two homes or a duplex on
single-family zoned lots through local ordinance or by ministerial approval. In
some cases, the bill allows lots to be split to build an additional 2 homes for a
maximum of 4 units for each lot. The bill sets forth the requirements local agencies
can impose to approve subdivisions and multi-units in single-family zoned areas.
This bill goes into effect January 1, 2022.
Senate Bill 10- Streamlines the process for cities to upzone single-family
neighborhoods and build small apartments in transit and/or jobs-rich areas. The
bill provides the groundwork for cities or counties to pass ordinances streamlining
the construction of small apartments of up to 10 units on a single parcel.
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47 Operations and Programs
The City uses the Engineering Standards in Capital Improvement Projects (CIP) and therefore
follows the minimum requirements for the incorporation of trees in capital projects. Trees are
incorporated, when possible, especially in rights-of-way improvements. Many times, the project
budget is not adequate and more emphasis is placed on other infrastructure. In other words,
trees are one of the first components cut. Trees are essential infrastructure that should be given
consideration in planning through completion of Capital Improvement Projects.
Challenges and Opportunities: Development
According to Municipal Code, not all development proposals require an arborist
report, it is up to the discretion of the Community Development Department.
Lack of coordination between Urban Forest Services and Community
Development in architectural review / planning in early stages of projects.
In many instances, development plans are not reviewed by an arborist and
do not provide consideration for the preservation of existing trees (e.g., zero
setbacks from the back of the sidewalk are not wide enough to allow for
preservation).
Lack of clarity on what trees need to be removed or what trees can stay during
development.
Trees in parking lots are being removed as a result of infrastructure conflicts and
development.
The community is undergoing a period of significant infill development and many
of the recent projects have conflicted with the City’s priorities to preserve existing
trees.
New tree plantings are cared for by developers for a relatively short amount of time.
Some of the trees planted by developers are in poor condition when Urban Forest
Services takes over their maintenance due to inadequate maintenance and young
tree establishment.
Residents contact ECOSLO to request trees for mitigation planting.
Urban Forest Services is tasked with inspection of tree protection measures during
construction, but staffing restrictions limit their ability to do so.
There are no standards for the replacement/planting of trees during CIP.
Placing the same emphasis on trees as other community infrastructure.
In the online survey, community members were invited to provide comments on
their thoughts on San Luis Obispo's urban forestry program. There was
overwhelming concern about the recent developments causing the removal of
mature trees, more than 50 responses were related to this topic.
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Operations and Programs 48
Design
Trees in the Mission Sidewalk Districts have iron tree grates and tree guards that allow for
pedestrians to walk over tree wells. Tree grates frequently require repairs, as the trunks and
roots expand and create trip hazards. Urban Forest Services and Streets Maintenance address
any maintenance needed to the grids. Sidewalk buckling also occurs regularly in the downtown
core as a result of tree root lifting. As such, maintenance also occurs regularly in the downtown
core, but in other areas of the community maintenance only occurs in conjunction with the
Pavement Management Plan (every 9 years). Some sidewalk maintenance projects require tree
root pruning. Any root pruning has to be approved by the City arborist and is then completed,
with little oversight, by the Streets Maintenance team. The team is not trained in urban forestry
and uses a stump grinder to prune roots, which is not consistent with industry standards and
can severely impact tree health.
Alternative designs are considered when possible. For
example, bricks are included when sidewalks cannot be
ground down. To allow for more space and water
infiltration, the City has implemented engineered soils
in the downtown core around carrotwood (Cupaniopsis
anacardioides), a species known to frequently cause
hardscape damage. While engineered soils increase
water infiltration, other design options are available
that hold more water (e.g., suspended sidewalks). As
long-term improvement projects occur, the City should
consider ways to expand the sidewalks and tree wells by implementing alternative designs to
provide trees with adequate space, especially in the downtown core and parking lots.
“Encourage creative
designs so that existing
trees can be maintained
for environmental and
visual esthetics.”
-Survey Respondent
Recommendations for UFSP Planning: Development
Ensure all development proposals are reviewed by an arborist in the initial planning
stages to provide adequate consideration and space for existing and planned trees.
Review and consider mature tree canopy growth.
Explore a requirement for a longer establishment time for new tree plantings that
are required as part of development.
Require developers follow minimum (ANSI A300) maintenance standards.
Ensure developers are responsible for reporting the status of their trees post-
occupancy.
Recognize trees are a critical infrastructure and plan to include them in
development and new construction projects on public land.
Ensure tree replacements after removals are not referred to ECOSLO.
Explore incentives for retention of large trees in new construction.
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49 Operations and Programs
In the rights-of-way of the downtown core, temporary parklets have been installed to provide
businesses with outdoor spaces during the COVID-19 pandemic. As these areas have been
successful at keeping the downtown area safe and lively, the City is considering creating a
permanent program for parklets. Tree maintenance has become more complex as a result of the
parklets. If parklets become permanent, the City should work with the Downtown Association to
explore their support in taking on some of the extra cost of this service.
The City is working on several infrastructure projects that have the potential to impact trees.
Several solar panel installation projects are underway including at the Bus Yard, Fire Station 1,
and Sinsheimer Pool parking lots. These projects do not interfere with tree canopy but should
initiate the development of internal policies on solar/tree conflicts as these are the first projects
of their kind. As planters for stormwater management, such as bioretention basins and
bioswales, become more common, Public Works may need policies that differ from typical street
trees. Trees incorporated in stormwater management infrastructure may require more frequent
maintenance or removal and replacement as their purpose is to enhance water quality and
reduce runoff.
“I am extremely grateful for SLO's urban forest. It is why I shop here rather
than in surrounding communities—all the shady parking.”
-Survey Respondent
Challenges and Opportunities: Design
Implement alternative designs to benefit the trees, but also decrease trip and fall
hazards.
Where planters are designed with a focus on stormwater mitigation and/or
bioremediation maintenance of stormwater infrastructure may require premature
removal of trees.
Internal policies around trees and solar collectors do not exist.
Some homeowners’ associations within the community discourage tree planting.
The Streets Maintenance program often uses a stump grinder to prune tree roots
when they are disrupting sidewalks and potentially causing hazards, which does not
follow current industry standards.
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Operations and Programs 50
Recommendations for UFSP Planning: Design
Explore the use of pervious pavements and suspended pavements to increase the
amount of uncompacted soil available to trees.
Partner with Downtown SLO to implement designs that can help reduce hardscape
conflicts involving large, mature trees in the downtown core.
Perform case studies to explore the products/designs available for stormwater
management and how they may work in San Luis Obispo.
The Tree Ordinance should exclude requirements for tree removal permits within
stormwater mitigation treatment areas.
Educate the public on the purpose of trees planted for stormwater
mitigation.
Assess parking lot sites and create larger tree wells whenever possible.
Explore policies and procedures that fit the community’s vision around solar/tree
conflicts in the Urban Forest Strategic Plan.
Explore and identify reasons why some homeowners and HOAs don’t want trees in
rights-of-way or on private property.
Identify strategies to increase appreciation for the urban forest (e.g., more species
choices, education, etc.).
Explore policies and procedures around tree and solar conflicts in the development
of an Urban Forest Strategic Plan.
Update policies for tree root pruning to follow ISA standards.
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51 Operations and Programs
Safety
Tree care is a very dangerous occupation, frequently cited as being one of the top 10 most
dangerous jobs in the US. In 2017, the Tree Care Industry Association (TCIA) reported that there
were 153 incidents, 92 resulted in fatalities and 63 were nonfatal in 2016. When Urban Forest
Services had more staff and a working crew, several incidents occurred and initiated safety
training around the topic, but most accidents are minor. Each division, including Urban Forest
Services, has a representative on the City’s Safety Committee which reviews accidents as they
occur and relays information back to their group.
Urban Forest Services staff are required to adhere to standards set forth by CAL OSHA (Group 3,
Article 12 Tree Work Maintenance or Removal), The American National Standard (ANSI Z133.1
Arboricultural Operations Safety Requirements and ANSI A300 Tree Care Specification), and ISA
Western Chapter of the International Society of Arboriculture pruning standards. In addition, all
staff are first aid CPR trained. Safety tailgates are reviewed every 2 weeks and staff complete
field assessments when they are in the field. In the past, Urban Forest Services was TCIA
certified. Although they are currently not certified, they continue to supplement safety training
with TCIA materials and participate in TCIA programs, such as the Aerial Lift Specialist Course.
Challenges and Opportunities: Safety
Training on equipment and safety has been suspended for almost 2 years, but in the
past Parks Maintenance, Urban Forest Services, and Ranger Services participated in
joint trainings.
Recommendations for UFSP Planning: Safety
Reenact training on equipment and safety.
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Operations and Programs 52
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53 Urban Forest Partners
Urban Forest Partners
Key urban forest partners were engaged to identify existing challenges and opportunities and to
provide insight and recommendations to strengthen the existing urban forestry program
structure. All engaged stakeholders were asked to respond to an initial survey and depending
upon response and level of engagement, some team members were invited to participate in
interviews for more nuanced discussions on maintenance, construction and development,
planning, and preservation. All stakeholders provided important information about the current
function of the Urban Forest Services program and potential staffing needs. Concerns, requests,
and suggestions from all stakeholders were of primary interest and were provided full
consideration in the development of the summary report.
Internal Partners
The urban forest in San Luis Obispo is managed by 4 city departments including Public Works,
Parks and Recreation, Community Development, and Administration. Cross-departmental
cooperation is often necessary to achieving urban forestry goals. While there is a great deal of
shared appreciation, resources, and effort, coordination and communication among
departments is generally ad hoc. Regularly set meetings are not in place, but communication
avenues are open and staff have high rapport and a desire to support each other when possible.
The different departments recognize that helping each other results in shared success yet also
appreciate the value of their independence.
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Urban Forest Partners 54
Parks and Recreation Department
The Parks and Recreation Department is responsible for managing over 4,000 acres of open
space with priority for maintaining viewpoints, building trails, outreach and education, and
safety and risk management. When needed, they conduct large-scale pruning for trees in the
Open Space areas. Urban Forest Services is responsible for maintaining trees in developed parks.
Parks and Recreation staff periodically help Urban Forest Services address emergency response
for rights-of-way trees. Discussions with this department revealed the following challenges and
opportunities:
Challenges and Opportunities: Parks and Recreation Department
Currently, park tree maintenance is reactionary and does not meet the community’s
expectations.
More attention should be placed on adequate staffing and the resources needed to
maintain park trees and mitigate hazards.
Recommendations for UFSP Planning: Parks and Recreation Department
Plan maintenance cycles to include park trees.
Develop and document inspection protocols for park trees to identify and mitigate
structural concerns and risk.
Train all maintenance staff to recognize and communicate hazardous
situations.
Document mutual aid policies, including available resources.
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55 Urban Forest Partners
Community Development Department
The Community Development Department oversees many programs including development
projects, building permits, code enforcement, affordable housing, and the flood control
programs. The Code Enforcement division is made up of Code Enforcement Officers and Code
Enforcement Technicians who provide information, investigate, and actively patrol for code
violations. When complaints are received for vegetation encroachment into the rights-of-way
Code Enforcement will make the initial vist, provide the propertry with a door hanger and pass
along the violation to Urban Forestry. When violations are related to trees, Code Enforcement
notifies Public Works who is then responsible for communication with property owners and
ensuring the hazard is mitigated. Public Works is also responsible for enforcing the Tree
Ordinance.
Challenges and Opportunities: Community Development Department
The Public Works Department (Urban Forest Services) is currently tasked with
enforcing the Tree Ordinance and code-related tree removals but the Department
does not have the staffing capacity to adequately provide this service especially when
violations occur on private property.
Standards for tree removal policy during development are not always clear and
objective.
Existing trees are not always provided full consideration during the planning process
for development proposals.
The 2019 Senate Bill 330, Housing and Accountability Act, limits proposed housing
developments to a total of 5 public hearings, putting the Community Development
Department in a position where they do not want to refer a hearing to the Tree
Committee but are required to in some cases to follow Municipal Code.
The role and expectations for the Tree Committee are sometimes unclear.
Recommendations for UFSP Planning: Community Development Department
Explore the feasibility for Code Enforcement to take on Tree Ordinance enforcement
duties through an impact study.
As development proposals are being planned, trees should be considered by all
parties and if removals occur, plan for tree planting requirements and mitigation
requirements.
Create a study group that examines the optimal role of the Tree Committee in the
development of the Urban Forest Strategic Plan.
Explore modifications to Municipal Code 12.24.090 Tree Removal in relation to Tree
Committee hearings.
Create a policy and procedures guide for the Tree Committee and conduct training
for new members.
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Urban Forest Partners 56
Fire Department
The San Luis Obispo Fire
Department is a full-service
fire department that protects
residents and visitors from
fires, medical emergencies,
and other dangers. The
department has an Insurance
Services Office Public
Protection Class 2 Rating,
which is only achieved by 2%
of fire departments in the
country (City of San Luis
Obispo Fire Department,
2021). In relation to trees, the department deals in fuel reduction, weed abatement, and
enforcing code for hazard trees. It is rare, but when hazard trees are reported as fire hazards, the
Fire Department will send out an inspector to see if the tree is on City property. If it is, the Public
Works’ city arborist or contract arborist assumes responsibility for mitigation.
Challenges and Opportunities: Fire Department
Fire response is not a consideration in the current disaster and preparedness
response plan followed by the Public Works Department.
Pinch points, or areas where if a fire were started it would spread into residential
areas, are not all identified nor inspected annually for hazards.
Recommendations for UFSP Planning: Fire Department
Develop/Update an overarching after-hours emergency response plan that includes
existing plans for storm and flood response, and fire.
Collaborate with the Fire Department to address trees that may pose fire hazards
and identify and manage vegetation where infrastructure may need defensible
space.
“The Urban Forestry Program needs to be part of a
City standing taskforce/working group with Fire
Department/Parks Dept/Public Works to conduct
wildland fire interface vegetation management
projects along open space boundaries, roadway
right of ways and city boundaries with areas such
as Cuesta Park to reduce ladder fuels and maintain
defensible space in the event of wildfire.”
-Survey Respondent
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57 Urban Forest Partners
Administration Department - Office of the City Manager
The City Administration Department is led by the City Manager who guides the day-to-day
activities for the City. The City Manager reviews and sets standards for the urban forest, such as
planting, trimming, monitoring, carbon sequestration, and urban cooling. Serving as the
Department Head, the Deputy City Manager manages Finance, Human Resources, the City
Clerk’s office, the Economic Development Program, the Office of Sustainability, and Information
Technology. High level goals and visioning for the urban forest have largely been spearheaded
by the Administration Department.
Challenges and Opportunities: Administration Dept. — Office of the City Manager
Although visionary documents call for robust tree planting efforts, plans have not been
developed for the implementation of 10,000 Trees, including planting, maintaining, and
ensuring tree survival.
While City leaders have provided clear direction for increasing tree planting efforts,
Urban Forest Services has concerns around the long-term maintenance of new trees as
they are understaffed and not currently able to meet these expectations.
The City intends to create a planning document for the urban forest such as a UFSP.
Recommendations for UFSP Planning: Administration Dept. — Office of the City Manager
Create and facilitate greater connection between Departments involved in caring for
the urban forest. Develop and document mutual aid policies, including resources.
Ensure that planning for 10,000 Tree initiative includes funding for tree establishment,
structural training, and long-term maintenance for trees planted in public space and
rights-of-way.
Partner with other departments and stakeholders to develop a comprehensive UFSP
with clear action steps to achieve immediate and long-term goals.
Create an Urban Forestry Core Team to aid in cooperation and communication among
departments involved with the urban forest.
Clear goals and plans in place for Urban Forest Services, partnering organizations, and
nonprofits.
Include trees planted as part of the 10,000 Tree initiative in maintenance plans.
Create and engage with a technical group, including CalPoly, ECOSLO, and other key
partners for the development of the Urban Forest Strategic Plan.
Consider including sidebars with culturally significant trees and tree-related
projects in the Urban Forest Strategic Plan (e.g., the “moon tree”, wood
utilization projects, and growing Italian stone pine from seed for use in parks).
Continue to promote the role importance of trees in long term planning, including the
General Plan. Climate Action Plan, etc.
Recognize urban trees as critical public infrastructure.
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Urban Forest Partners 58
Administration Department — Office of Sustainability
The Office of Sustainability was created with the vision for San Luis Obispo to be a “thriving,
resilient, and sustainable community” and works to achieve this through positive leadership,
collaboration, and policy development. The Office has several programs to support this goal,
including Natural Resources and Climate Action. Natural Resources oversees greenbelts, land
stewardship, natural history education, environmental restoration, and environmental mitigation.
These programs include habitat restoration and tree planting in open space. San Luis Obispo
has ambitions to curb the effects of climate change through an aggressive tree planting
initiative, which will largely occur in open space. The Natural Resources Environmental
Restoration program focuses on creek restoration, tree planting, wetland and natural habitat
improvements and considering these aspects in development processes.
Challenges and Opportunities: Administration Department — Office of Sustainability
There is an opportunity to increase collaboration between the Office of Sustainability
— Natural Resources and Urban Forest Services, as there is shared interest in the
urban forest.
Without a plan for the implementation or tracking tree planting as part of the 10,000
Tree initiative, Urban Forest Services is not sure how many trees will be planted in the
built areas of the community.
Collaborating Departments have ambitious goals around the urban forest and Public
Works Urban Forest Services is not always included in visionary conversations.
The transition from urban forest to open space is clear, but urban forest managers
would like less distinction and more of a natural transition between urban forest
trees and trees in open space.
Recommendations for UFSP Planning: Administration Department - Office of
Sustainability
Ensure all key Departments and organizations involved in managing the urban forest
are engaged in planning and implementation for the 10,000 Tree initiative.
Record details each time a new tree is planted for tracking purposes.
Collaborate with the Office of Sustainability, Natural Resources to create a transition
zone between urban forest trees and open space trees by using an appropriate mix of
native species.
Explore interdepartmental relationships and needs/opportunities for better
communication and inclusive planning where appropriate.
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59 Urban Forest Partners
Public Works Department — Maintenance Operations (Parks)
Public Works provides safe mobility options and maintains public infrastructure and assets in
San Luis Obispo. Public Works’ programs are divided between the Deputy Director, the City
Engineer Deputy Director, and Maintenance Operations. The City Engineers manage the CIP
Programs in addition to Transportation. The Deputy Director — Maintenance Operations
manages Facilities, Fleet, Parks, Street, and Urban Forest. The Parks division manages
approximately 550 acres of parks and a large number of park trees. The Parks maintenance staff
monitor all trees in parks, provide clearance, and remove dead trees. When trees require service,
they fill out a work order to be sent to Urban Forestry.
Challenges and Opportunities: Public Works Department — Maintenance Operations
(Parks)
Trees in parks are not maintained regularly, which has caused a backlog of
maintenance and impacted tree health and aesthetics in parks.
Over the past two years, Urban Forest Services has not been able to complete the
work orders submitted by Parks Maintenance, creating a significant amount of
additional work for Parks Maintenance staff to report and/or address, such as broken
branches, branches blocking sidewalks, hangers, and litter clean up.
San Luis Obispo’s parks are the unintended hosts of a consistent homeless
population, which cause damage to park trees through improper pruning or
destruction of young trees.
Tree care is considered in Parks Maintenance Plans, although to a lesser extent than
other infrastructure.
Parks provide ample, irrigated space for trees.
In most cases, the initial Parks Maintenance Plans underestimate the number of trees
and amount of maintenance that will be needed in the future.
Recommendations for UFSP Planning: Public Works Department — Maintenance
Operations (Parks)
Inventory trees in established parks and include their maintenance in pruning cycles,
work plans, and maintenance budgets.
Continue working with the Parks Maintenance staff on trainings such as hazard
identification, chainsaw safety, and basic tree pruning.
Current and future growth/planning — Involve Urban Forest Services in new park
plans and include trees in new development maintenance plans.
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Urban Forest Partners 60
Advisory Bodies
San Luis Obispo Tree Committee
The Tree Committee is an advisory body that provides recommendations to City Council and
City Staff after reviewing tree-related proposals and requests. If the City Arborist cannot approve
a tree for removal (non-development) the application is typically determined by the Tree
Committee. Members of the committee may have some expertise in arboriculture and/or an
interest in trees. The majority of the Tree Committee’s time is spent reviewing development
proposals but they also engage in the appeal process around tree removals that are deemed a
hazard and the nomination of Heritage trees. Commonly, topics include whether or not removal
is warranted and/or if the proposed mitigation planting is adequate. The Committee reviews
each topic and suggests recommendations on policies and regulations relating to the urban
forest (e.g., invasive species management, specimen or rare species, overcrowding issues,
mitigation requirements, planning to offset the canopy loss, and reasonably allowing for
development). Currently, the Tree Committee is housed in the Public Works Department, which
provides a staff member as a liaison/subject matter expert to the Committee.
Challenges and Opportunities: San Luis Obispo Tree Committee
The roles, responsibilities, and authority of the Tree Committee are ambiguous.
The Tree Committee is housed within the Public Works Department yet spends the
majority of deliberations on topics relating to private trees.
The community is undergoing a significant amount of infill development, partially
related to an increased demand for housing, commercial sites, and the recent state
Housing Mandate. Increasingly, the Tree Committee is being asked to review these
development plans.
The Tree Committee is the last governing body to review large development
proposals. In most situations, by the time these projects are presented to the Tree
Committee, they have already been approved and the Tree Committees
recommendations may or may not be taken into consideration.
There is no requirement for City staff involved with the proposal process to report
back so that the Tree Committee knows whether or not their recommendations are
being implemented.
Currently, neither the Tree Committee nor the City Arborist serve as a liaison/
support for the Architectural Review Commission yet this Commission reviews
projects that involve consideration for tree preservation and removal permits.
The Tree Committee has a limited advocacy role for urban forestry budgeting
through an annual report to the City Council that includes desired improvements.
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61 Urban Forest Partners
Recommendations for UFSP Planning: San Luis Obispo Tree Committee
Perform case studies on the roles and responsibilities of Tree Committees in various
model cities to help develop a clear purview and purpose for San Luis Obispo’s Tree
Committee.
Consider the amount of authority the Tree Committee should have in large
development proposals.
Clearly communicate the purpose of the Committee.
Create guidance on roles and responsibilities and train new members.
Consider changes to the organizational structure, specifically moving the Tree
Committee to a Department with a larger focus on policies and regulations for the
entire urban forest (e.g., the Office of Sustainability or Community Development).
Make an ISA-certified arborist available to support both the Architectural Review
Committee and Tree Committee for technical questions involving tree health and
preservation strategies.
“I recently had to remove a tree on our
property. The process was good. The tree
committee members listened, the arborist
was helpful, and it was easy to see that the
City is working to maintain trees citywide.”
-Survey Respondent
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Urban Forest Partners 62
San Luis Obispo City Council
The San Luis Obispo City Council is a five-member board consisting of the directly-elected
Mayor and four City Council Members. The City Mayor is elected to a two-year term, whereas
City Council Members have four-year terms. The City Council is the primary legislative authority
that sets policy, adopts ordinances, approves programs, appropriates funds, adopts budgets,
and approves contracts. The City Council outlines four overarching goals for San Luis Obispo,
including:
Climate action, open space, and sustainable transportation
Housing and homelessness
Economic resiliency, recovery, and sustainability
Diversity, equity, and inclusion.
Challenges and Opportunities: San Luis Obispo City Council
The community and City Council are supportive of trees and understand that tree
canopy is integral to the culture and character of the community.
The budget for tree care is often one of the first to decrease during economic
downturns.
City Council Members are not always aware of the urban forest needs and the
actions and associated budget required to meet visionary goals.
Recommendations for UFSP Planning: San Luis Obispo City Council
Develop a robust and comprehensive Urban Forest Strategic Plan (UFSP) and clearly
communicate the following:
Value and benefits of the urban forest
Community vision and direction for tree care and canopy cover
Long term goals and objectives, including long and short-term action steps
and proposed timelines for meeting them
Maintenance standards for trees, including pruning cycles and industry
BMPs
Use direction from the UFSP to develop annual work plans in support of budget
requests.
Deliver an annual State of the Urban Forest Report to Council, outlining successes of
the UFSP as well as challenges for implementation.
Designate a liaison that can advocate for tree maintenance needs and goals.
Advocate for the importance of community trees and predictable, stable
funding so that tree maintenance can meet community expectations.
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63 Urban Forest Partners
External Partners
Environmental Center of San Luis Obispo (ECOSLO)
ECOSLO is a 501(c)(3) nonprofit organization that serves the community of San Luis Obispo.
ECOSLO was originally started in 1972 by Cal Poly students with the goal of cleaning up polluted
creeks in the City. Now, ECOSLO is the premier organizer for sustainability, environmental
advocacy, and environmental justice in the community. ECOSLO’s programs include various
environmental cleanups, green business certifications, county park improvements, as well as
urban tree planting.
The ECOSLO urban tree planting program started in 2019. It is made possible by grant funding
from CAL FIRE and California ReLeaf and is largely volunteer supported. ECOSLO currently
partners with the City to plant trees on city street parkways and on residential front yards. Tree
care and maintenance is done through a volunteer adopt-a-tree program for which anyone can
volunteer. The organization is interested in exploring additional opportunities to partner with
the City in support of urban forestry.
Challenges and Opportunities: ECOSLO
Communication and planning with multiple city departments on tree planting
locations, tree removals, watering needs, and other maintenance needs is difficult
for ECOSLO to navigate.
Under ideal circumstances, ECOSLO would ask for more support, but they
limit their requests to Urban Forest Services’ support because they recognize
that staff are currently overstretched.
ECOSLO would like to explore a more clearly defined partnership with the city.
Community members often reach out to ECOSLO for tree removals or replacement
trees, but these requests have to be re-routed because these services are the
responsibility of Urban Forest Services.
ECOSLO is integral to the planting and maintenance of public trees throughout the
community, a greater emphasis should be placed on continued collaboration, clear
communication, and joint strategic planning.
Recommendations for UFSP Planning: ECOSLO
Explore existing partnerships with ECOSLO to optimize the relationship for both
parties:
Create a central chain of communication and identify a primary contact from
the city to coordinate with ECOSLO and facilitate projects.
Engage with ECOSLO during the development of the Urban Forest Strategic Plan to
discuss existing partnerships and future opportunities.
Discuss and clarify expectations for the 10,000 Tree initiative, including specific
planting sites and their intended planting date.
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Urban Forest Partners 64
Downtown SLO
Downtown SLO is a nonprofit organization formed in 2007 with the mission to promote an
economically vibrant downtown in San Luis Obispo. Downtown SLO has several proclaimed
values, including creating community, promoting sustainability, prioritizing the environment,
helping businesses thrive and making downtown a beautiful place to visit. Partners of
Downtown SLO include fee-paying businesses, volunteers, nonprofit organizations, residents,
visitors and the City of San Luis Obispo. Many of the regular events in the downtown core are
run by the nonprofit, including the Thursday Night Farmers Market and Concerts in the Plaza
(Downtown SLO, 2021).
Downtown SLO hires Downtown
Ambassadors, professional staff that
clean and maintain tree grates or
remove suckers and small limbs below
6 feet if they impede pedestrian paths.
Historically, there has been a group of
tree care volunteers called Downtown
Foresters who have assisted with tree
care in the downtown core.
Challenges and Opportunities: Downtown SLO
There is opportunity for Urban Forest Services to further engage Downtown SLO in
redevelopment projects, maintenance, and education and outreach.
The upcoming downtown pavement project could be an opportunity to explore
designs that promote large-stature shade trees.
Large ficus trees provide a significant amount of canopy cover for downtown
streets, but present several challenges.
Fruit and wildlife (e.g., birds, etc.) create aesthetic and nuisance conditions
that are a concern for patrons.
Many of the trees are aging and a succession plan is needed.
Most agree that large shade trees are important to the character of
downtown, but would like to explore other species options with an emphasis
on reducing litter and pavement conflicts.
As a result of COVID-19 and staffing changes, the Downtown Foresters have been
less active than before.
“I think it is time to find a species of tree
to start replacing the ficus trees
downtown that are tearing up sidewalks.”
-Survey Respondent
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65 Urban Forest Partners
California Polytechnic State University (Cal Poly)
Located in San Luis Obispo, Cal Poly is a public university and one of the two polytechnic
colleges in the California State University system. Cal Poly’s motto is “learn by doing,” hence
many of the academic programs promote hands-on learning. Cal Poly offers more than 60
majors across 6 different colleges, many falling under the college of Agriculture, Food and
Environmental Sciences. The college includes the major Forest and Fire Science that gives
hands-on experience in forestry, as well as access to a 3,800-acre field laboratory site. Cal Poly
has been recognized as a Tree Campus USA by the Arbor Day Foundation since 2014, and
boasts the most diverse urban forest of any college campus in the nation (Cal Poly, 2020).
Cal Poly has previously been involved with San Luis Obispo’s urban forest. Previous projects and
partnerships include work on the City’s approved tree species list, spot inventories done by
student interns, and graduate work on urban forest planning. Volunteers from Cal Poly’s
arboriculture class have also helped with city tree planting in the past.
Recommendations for UFSP Planning: Downtown SLO
New downtown development and reconstruction projects should emphasize
designs that support large-stature shade trees.
Upcoming downtown pavement project.
Construction plans should include consideration for suspended sidewalks and/or
plazas with pervious pavements to support large trees and canopies.
Consider areas of the Monterey District, Mission Plaza Concept, and
Downtown District.
Engage the community to clarify the vision for the future character and role of trees
downtown.
Create a species palette for downtown, including large-stature shade trees. Develop
a successional planting plan to replace aging ficus.
Engage with existing volunteers (e.g., Downtown Foresters) to formalize
relationships and goals.
Challenges and Opportunities: Cal Poly
Many opportunities to acquire and recruit Cal Poly students to become involved in
the Urban Forest program through volunteering, interning, or other means.
There are currently no formal programs or partnership agreements with Urban
Forestry Services.
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Urban Forest Partners 66
Pacific Gas and Electric (PG&E)
Pacific Gas and Electric are responsible for the management of trees located under utility lines in
San Luis Obispo. Municipal Code requires public utilities to acquire a permit before completing
any utility work that impacts adjacent trees. State law allows utility providers to remove or prune
trees as necessary to provide safe clearance. PG&E was not engaged in the development of this
report, but should be in future planning efforts around the urban forest.
Recommendations for UFSP Planning: PG&E
Increase communication with PG&E.
Challenges and Opportunities: PG&E
Urban Forest Services has established communication avenues with local utility
providers, but in most instances, they do not learn about work occurring on public
trees until after it is underway.
Recommendations for UFSP Planning: Cal Poly
Engage with Cal Poly students and faculty to explore opportunities for students and
programs to support the urban forest and gain valuable hands-on experience.
Increase collaboration with Cal Poly through internship and volunteer opportunities.
Consider student help with expanding the species list, inventory
management and updates, new tree plantings, and tree maintenance.
Engage forestry students in the UFSP planning process.
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67 Organizational Structure and Staffing
Organizational Structure and Staffing
Staffing
The urban forestry program has been undergoing organizational and staffing changes over the
past 10 years. However, the most significant decreases in the staffing levels have occurred over
the past two years. Currently, Urban Forest Services employs one full-time Urban Forest
Supervisor (Interim) and one full-time Tree Assistant (Figure 5). The Department is currently
assessing staffing needs with consideration for the soon-to-be-developed Urban Forest
Strategic Plan, the 10,000 Trees initiative, and existing responsibilities.
Many of the organizational changes in the past 10 years have followed the 2011 Management
and Performance Audit of the Public Works Department, a document that assessed the
organization’s structure and provided recommendations for the program (Management and
Performance Audit of the Public Works Department, 2011). The audit recommended the Urban
Forest Supervisor report to the Public Works Director and manage an in-house, 3-person crew.
Some of the asset management recommendations outlined in the report have not been
adopted by the urban forestry program and positions have not been backfilled as employees
transferred, retired, or left the City. As a result, the program is understaffed and there is a
backlog of maintenance needs and an anticipated increase in future workloads from infill
development and increased tree planting. Urban Forest Services has fallen behind on the
majority of maintenance tasks they are responsible for.
Figure 5: Current Staffing Structure of Urban Forest Services
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Organizational Structure and Staffing 68
Currently, Public Works has begun to use a contractor to perform the scheduled maintenance of
area pruning. An in-house crew would continue to address reactive maintenance,
training/structural pruning of young trees, specialized pruning, and emergency response. While
contract crews can lead to greater efficiencies and reduced liability for the City, it is important to
maintain an in-house crew that has a vested interest and knowledge of community assets and
able to put trees into context with other city policies, goals, and infrastructure.
In addition to Urban Forest Services, other departments and teams have responsibilities for
urban forest assets. Although this project did not include a full review of tasks or staffing in
those other departments, several duties relating to the urban forest fit the purview and skillsets
of other departments. For example, a Development Review Arborist could provide advise during
development planning, review development proposals, and fulfill other duties that relate to
private trees. Furthermore, a Volunteer Coordinator position placed in the Parks and Recreation
Department could organize outreach, community engagement and education for the urban
forest program as these roles fit the vision of this department. As the recommendations in this
document address optimal staffing for the urban forest and consider the addition of staff in
other departments, it should be reviewed and discussed by appropriate city staff to ensure
agreement.
Challenges and Opportunities: Organizational Structure
Positions have not been filled in the last 2 years and the program is severely
understaffed.
Maintenance requests from other divisions are submitted to Urban Forest
Services, but in most cases, there is not enough staff to complete the work.
Staff are not able to complete all of the assigned duties.
Progress on the current high-level goals is not feasible for the Public Works
Department with the current staffing levels and budget.
Maintenance and administrative roles are being carried out by the same individual,
yet these roles require different skillsets and full-time attention.
The city has followed a model where a subset of individual trees are managed by
multiple departments but does not have a designated urban forest team to facilitate
a shared vision and allows for inconsistent standards in tree care and programming
inefficiencies.
While interdepartmental staff collaborate well and often coordinate for success,
these relationships and overall program efficiency could be improved by
documenting policies, responsibilities, and procedures. Coordination and
collaboration with other departments responsible for shared visioning and care for
the urban forest could be improved.
Not all of the work provided by Urban Forest Services fit the vision of the Public
Works Department.
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69 Organizational Structure and Staffing
Recommendations for UFSP Planning: Organizational Structure
Explore the development of a comprehensive staffing structure that ensures both
administrative and maintenance roles related to the urban forest are provided full
attention.
Collaborate with all urban forest service providers to identify optimal structure
for consistent and efficient services.
Create a team consisting of the Maintenance & Operations Manager, Natural
Resources Manager, and Development Review Arborist (NEW) to administer
consistent vision and policy across departments and teams engaged in managing
urban forest assets and is who responsible for the stewardship of the Urban Forest
Strategic Plan and liaison with planning, development, Tree Committee, and City
Council.
Advocate for the entire urban forest.
Set goals for canopy cover, sustainability, and climate action.
Create and share policy, visionary documents, and an overall budget.
Increase staffing levels, include the following positions (see Figure 6):
2 FTE Arborists to create an in-house crew in the Public Works Department.
1 FTE Development Review Arborist (potentially located in the Community
Development Department).
1 FTE Volunteer Coordinator (potentially located in the Parks and Recreation
Department).
Explore the need for additional administrative support to address permitting
and applications.
Support and collaborate with all other departments responsible for the urban forest.
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Organizational Structure and Staffing 70 Figure 6: Staffing Recommendations Page 570 of 748
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Organizational Structure and Staffing 70
Positions within the Public Works Department
1 FTE Arborist Coordinator. This is a lead arborist position that reports to the Maintenance and
Operations Manager or another maintenance supervisor. This position should have the same
duties as an Arborist but act as a crew lead at times.
1 FTE Arborist. Together, with the Arborist Coordinator these positions should create one
functional in-house crew. At a minimum, the tree crew should contain one Arborist Coordinator
able to tree climb and work from a bucket truck as well as two additional arborists. The tree
crew should have the following duties:
Respond to internal work requests.
Address clearance and visibility of City owned trees.
Conduct structural pruning in parks and city facilities, training pruning, and watering
trees.
Provide emergency response.
Conduct tree inspections and risk assessments on public trees along streets, in parks,
and at city facilities when a hazard has been identified (TRAQ qualification is preferred).
Young tree care and watering.
1 FTE Maintenance Contract Coordinator. In addition to other contract monitoring within the
Public Works Department, this position provides oversight of the contract for cycle pruning and
large tree removals.
Oversee the contract for cycle pruning and large tree removals (ISA certification is
preferred).
Positions outside of Public Works Department
Several key positions are needed in other departments to support urban forestry goals. Their
placement is flexible and all partners should be involved in determining the optimal placement.
1 FTE Development Review Arborist. This position, potentially located within the Community
Development Department, should have the following duties:
Review all development proposals.
Advise during development planning and review.
Ensure contractors are following the Tree Ordinance and ANSI standards.
Administer Removal Applications.
Apply ordinances and evaluate trees.
Respond to resident correspondences.
Conduct tree inspections and risk assessments on private trees when a hazard has been
identified (TRAQ qualification is preferred).
Liaison to other departments, City Council, the Tree Committee and Architectural
Review Commission, work with partners and stakeholders.
Participate in tree related outreach activities, support Parks and Recreation in the
annual Arbor Day events.
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71 Organizational Structure and Staffing
1 FTE Volunteer Coordinator. This position, potentially located within the Parks and Recreation
Department, should have duties that relate to education and outreach events that impact the
entire urban forest, even trees cared for by Public Works. This would allow the City to expand
formal volunteer opportunities and community engagement around trees.
Conduct large outreach and education events, including those related to public trees
managed by Urban Forest Services (e.g., Arbor Day).
Further expand relationships with City Departments and partnering organizations
caring for the urban forest.
Coordinate with Public Works and ECOSLO on an Adopt a Street Tree program.
Lead volunteer efforts.
Equipment
Urban Forest Services has the equipment needed for a functional in-house crew. Staff have
access to an aerial lift, truck, and chipper. Other equipment, such as the brush chipper and
mowers, are shared amongst Departments. Once an organizational structure, services, and work
plans are agreed upon, Urban Forest Services can explore additional equipment needs,
potentially during the development of an Urban Forest Strategic Plan.
Challenges and Opportunities: Equipment
Re-examine equipment needs once there is consensus on the appropriate
organizational structure.
The Parks Maintenance crew has one chipper truck and the City has a backup
chipper truck. During winter storms, chipper trucks can be high in demand and not
available, limiting clean up efforts to one crew.
Several community survey respondents were concerned with the amount of fossil
fuels being used to maintain the urban forest.
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Organizational Structure and Staffing 72
Contract Management
Approximately 95% of tree maintenance is currently conducted by contractors. In the current
agreement, contractors are required to provide the City with tree maintenance forms that log
the maintenance performed each day. The following work is being contracted:
Tree pruning
Tree removal
Stump grinding
Emergency response
The ISA-certified Interim Urban Forest Supervisor has been working with the contractor to
ensure maintenance meets the standards of Urban Forest Services, industry standards, and
community expectations. The Public Works Department recently hired an in-house Maintenance
Contract Coordinator who will be tasked with overseeing the tree maintenance contract as well
as other contracted work within the Department. While this will help with the administrative
aspects of the contract agreement, it is important that an ISA-certified arborist is involved in
work planning and inspections of contract work.
Currently, the contractor has their own inventory and plans to integrate data on community
trees to the City’s inventory database quarterly. Periodic data transfers do not allow the City to
have a real time, up-to-date inventory. Ideally, contractors would update the City’s inventory.
Recommendations for UFSP Planning: Equipment
Evaluate equipment needs.
Assess whether the City should replace the current water truck or fully
contract out this service (also consider other young tree care duties).
Assess whether a stump grinder would be useful, or if this work will
continue to be contracted out.
Assess whether the City should purchase an auger to aid urban forest
partners in tree planting.
Evaluate where redundancies would be useful.
Explore the carbon use and capture that results from urban forestry operations.
Explore ways to reduce the amount of carbon (carbon footprint) produced
in the management of the urban forest.
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73 Organizational Structure and Staffing
Challenges and Opportunities: Contract Management
Contractors are not providing updates to the city’s tree inventory data, rather they
are using their own internal system.
Depending on the size of the in-house crew, Urban Forest Services may need to
explore additional contract funding in the future.
Additional contract services will be needed to successfully complete the future
increase in planting and maintenance expected as part of the tree planting
initiative.
The city recently transitioned contract monitoring to the Maintenance Contract
Coordinator and although they are experiencing positive results, contract services are
only sporadically monitored by a certified arborist.
Recommendations to follow up for UFSP Planning: Contract Management
Require contractors to update the city’s inventory data as work occurs.
Confirm species
Update DBH as needed
Update condition as needed
Explore additional contract needs for expanded services (e.g., watering, new tree
establishment).
Ensure a certified arborist is regularly monitoring/inspecting contractor’s work to
avoid conflict of interest with maintenance contractor.
Monitoring can be done in-house (e.g., consider requirements for ISA
certification for the Maintenance Contract Coordinator position) or through a
contractor/company.
Ensure contractors are completing and documenting tree inspections as they
conduct routine pruning.
Document risk factors, health, and pest/disease concerns that cannot (or will
not) be mitigated through maintenance.
Continue to contract regular street tree maintenance / cycle pruning.
Continue to implement contracts that:
Can be easily extended if the level of tree care provided by the contractor is
satisfactory.
Clearly state the goals for contract services.
Require contractor adhere to all ANSI and ISA standards and BMPs for tree
care operations.
Require that pruning be completed or supervised by an ISA certified arborist
or ISA certified tree worker.
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Organizational Structure and Staffing 74
Funding
Funding for the urban forest program within Public Works is sourced from the General Fund and
is expected to be $680,571 in FY 2020-2021. Preserving and maintaining the urban forest is one
of four strategic goals laid out for Public Works in San Luis Obispo’s 2021-2023 Financial Plan.
As part of this goal, the Financial Plan provides funding projections to meet the objectives of
completing the Urban Forest Strategic Plan, a comprehensive tree inventory update, creating a
database tracking system, and more pruning and maintenance.
The 2021-23 Financial Plan calls for an overall 35% budget
cut to Urban Forest Services’ FY 2020-2021 budget, for a FY
2021-22 budget of $441,419. A large portion of this budget
cut is in staffing, the budget of which is being cut by 40%
due to the open positions that were not filled during the
Departments assessment/evaluation period. While there are
staffing constraints to the program, contract services are
increasingly meeting needs for tree maintenance. In recent
years, the City has increased funding to contract services
which has lessened the backlog of service requests and
made tree maintenance more proactive. The budget for
contract maintenance services has increased from $60,000
to approximately $175,000. A portion of the funding
allocated to contract services is also to support the
development of an Urban Forest Strategic Plan.
Challenges and Opportunities: Funding
Historically, Urban Forest Services has been underfunded.
Securing steady funding for Urban Forest Services that does not fluctuate based on
external factors and take future growth into consideration.
City leaders and the community support the urban forest and may be willing to
provide more financial support recommended maintenance and service levels.
Increase investment in proactive, preventative maintenance by exploring
options to increase the frequency of pruning events for public street trees.
Creating a sustainable funding plan for Urban Forest Services that forecasts and
plans the budget for more than 2 years into the future.
All of the current funding for the program comes from the General Fund.
“The city urban forestry
department is woefully
underfunded.
Subsequently tree
maintenance is not
completed in a timely
manner and the trees
suffer for it."
-Survey Respondent
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75 Organizational Structure and Staffing
Recommendation for UFSP Planning: Funding
Create maintenance zones and work plans that includes all trees in the rights-of-way,
streets, medians, parks, and city facilities and budget for their maintenance.
Plan for increased maintenance costs for proactive care on a 6-year cycle.
Plan for increased contracted or in-house work to support the robust tree
planting initiative.
Plan to include the cost of maintenance for newly planted trees along streets,
in parks, rights-of-ways, and at city facilities, including all trees planted by
partnering organizations.
Use the current assets, workloads, and anticipated growth in staff and new tree
planting to determine what the future resources are needed.
Create a long-term budget for the 10,000 Tree initiative and consider it in future
funding projections.
Develop a sustainable funding plan that looks further than the current budget cycle
of two years.
Partner with ECOSLO as conduit for donations to help support the urban forest and
volunteer services.
Explore implementing a Tree Fund that is used toward tree planting or urban forest
conservation easements.
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77 Policy and Regulation
Policy and Regulation
Urban forest management operations are influenced by and subject to regulations, policies, and
guidance from federal, state, and local direction. The following section provides a summary of
the regulatory and guiding policies explored during this assessment of the urban forestry
framework in San Luis Obispo. Additional regulations and policies may also apply.
Federal and State Law
Endangered Species Act
Signed in 1973, the Endangered Species Act provides for the conservation of species that are
endangered or threatened throughout all or within a significant portion of their range, as well as
the conservation of the ecosystems on which they depend. The listing of a species as
endangered makes it illegal to "take" (i.e., harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, collect, or attempt to do these things) that species. Similar prohibitions usually extend
to threatened species.
Migratory Bird Treaty Act (MBTA)
Passed by Congress in 1918, this Act defines that it is unlawful to pursue, hunt, take, capture, kill,
possess, sell, purchase, barter, import, export, or transport any migratory bird, or any part, nest,
or egg or any such bird, unless authorized under a permit issued by the Secretary of the Interior.
The Migratory Bird Treaty Act can impact forestry operations during times when birds are
nesting, which may delay work in order to avoid violating the MBTA.
Vegetation Management Standards
In California, all utility providers are subject to General Order 95; Rule 35 Vegetation
Management (California Public Utilities Commission, revised 2012) and FAC-003-2 Transmission
Vegetation Management (NERC), which outline requirements for vegetation management in
utility easements. These requirements include clearance tolerances for trees and other
vegetation growing in proximity to overhead utilities.
California Urban Forestry Act
Section 4799.06-4799.12 of the California Public Resources Code defines a chapter known as the
California Urban Forestry Act. The Act defines trees as a “vital resource in the urban environment
and as an important psychological link with nature for the urban dweller.” The Act also
enumerates the many environmental, energy, economic, and health benefits that urban forests
provide to communities.
The purpose of the Act is to promote urban forest resources and minimize the decline of urban
forests in the state of California. To this end, the Act facilitates the creation of permanent jobs
related to urban forestry, encourages the coordination of state and local agencies, reduces or
eliminates tree loss, and prevents the introduction and spread of pests. The Act grants the
authority to create agencies and mandates that urban forestry departments shall provide
technical assistance to urban areas across many disciplines (while also recommending numerous
funding tools to achieve these goals).
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Policy and Regulation 78
Model Water Efficient Landscape Ordinance (MWELO)
To promote the conservation and efficient use of water and to prevent the waste of water, a
Model Water Efficient Landscape Ordinance (MWELO) was adopted in 2009 and later revised in
2015. The Ordinance requires increases in water efficiency standards for new and retrofitted
landscapes through the use of more efficient irrigation systems, greywater usage, and onsite
stormwater capture. It also limits the portion of landscapes that can be covered in turf.
California Global Warming Solutions Act
In 2006, the California Global Warming Solutions Act (Assembly Bill 32) was implemented to
reduce greenhouse gas emissions. Through this Act, California was the first state in the nation to
initiate long term measures to help mitigate the effects of climate change through improved
energy efficiency and renewable technology. California approached the goal to reduce
emissions to 1990 levels by 2020 through direct regulations, market-based approaches,
voluntary measures, policies, and programs. The 2015 update set targets to reduce greenhouse
gas emissions to 40 percent below 1990 levels by 2030.
California Solar Shade Control Act
Passed in 1978, California’s Solar Shade Control Act supported alternative energy devices, such
as solar collectors, and required specific and limited controls on trees and shrubs. Revised in
2009, the Act restricted the placement of trees or shrubs that cast a shadow greater than ten
percent of an adjacent existing solar collector’s absorption area upon the solar collector surface
at any one time between the hours of 10am and 2pm.
The Act exempts trees or shrubs that were:
Planted prior to the installation of a solar collector
Trees or shrubs on land dedicated to commercial agricultural crops
Replacement trees or shrubs that were planted prior to the installation of a solar
collector and subsequently died or were removed (for the protection of public health,
safety, and the environment) after the installation of a solar collector
Trees or shrubs subject to city and county ordinance
Climate Adaptation Actions for Urban Forests and Human Health
In July 2021, the U.S. Forest Service published Climate Adaptation Actions for Urban Forests and
Human Health, a comprehensive document that synthesizes information and recommends
action steps for professionals and communities in expanding the role of urban forests for
climate adaptation. The central component to Climate Adaptation Actions for Urban Forests and
Human Health is the Urban Forest Climate and Health Menu. This menu provides information
and ideas for urban forestry projects to improve climate and human-health related outcomes
with a clear, organized step-based approach. The Urban Forest Climate and Health Menu is
structured with three chronological steps going from conceptual stages to action stages to
accomplish each of nine core strategies. These strategies are:
Activating social systems for equitable climate adaptation, urban forest and health
outcomes
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79 Policy and Regulation
Reducing impact of human health threats and stressors using urban forests
Maintaining/increasing extent of urban forest and vegetative cover
Sustaining or restoring ecological functions of urban ecosystems
Reducing impact of physical and biological stressors on urban forests
Enhancing taxonomic functional on structural diversity
Altering urban ecosystems toward new and expected conditions
Promoting mental and social health in response to climate change
Promoting human health co-benefits in nature-based climate adaptation
This report solves the common challenge of synthesizing broad science-based information into
actionable steps for communities. It can be used in developing new climate adaptation plans, to
explore benefits and drawbacks of existing adaptation plans, and to generate discussions about
community needs with regards to urban forest development.
Guiding Documents for the Urban Forest
Municipal Code
San Luis Obispo Municipal Code has seven titles that include provisions that impact trees, tree
care, or the urban forest.
Title 1 General Provisions cross references Tree Regulations (Chapter 12.24) for the penalties
applied for violating code.
Title 8 Health and Safety defines rubbish to include tree trimmings. Requires the removal of
fallen or standing trees that are causing dangerous obstructions or preventing the flow of water
in streambeds or other bodies of water.
Title 10 Vehicles and Traffic includes provisions for trees in visibility and clearance
requirements. Requires reporting any accident that causes damage to trees. Designates oversize
and overweight vehicle permit holders responsible for repairing any resulting damage to public
property, including trees. Prohibits the permit holder from trimming city trees.
Title 12 Streets, Sidewalks, and Public Places prohibits any structures from encroaching on or
coming into contact with street trees. Outlines the encroachment permit process, and trees can
be included as obstructions. Provides protections to trees and tree-stakes/guards along creeks,
riparian areas, and city properties adjacent riparian areas. Encourages tree and landscape
plantings in parking lots as well as alternative designs, such as porous pavement, to retain
existing trees in or near parking areas.
The Tree Ordinance, Chapter 12.24 Tree Regulations, establishes policies and regulations on the
maintenance, removal, and preservation of trees. Explains the structure and duties of the tree
committee. Requires a street tree list, major street tree list, and, when applicable, a tree planting
plan for developments. Requires following standards and procedures for tree planting and
maintenance.
Sets criteria for tree removal and explains the tree removal permitting and appeals process.
Requires mitigation in the case of tree removal. Designates the City responsible for sidewalk
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Policy and Regulation 80
maintenance resulting from street tree conflicts. Designates the City responsible for maintaining
trees on public property. Allows private property owners to hire certified professionals to prune
trees or repair sidewalk damage out of the maintenance cycles, but at their own expense.
Prohibits hazardous trees on private property, outlines the abatement notice process, and
designates responsibility to property owners for addressing hazardous trees. Requires public
utilities to obtain a permit to maintain trees adjacent to utility infrastructure. Requires tree care
contractors to have the appropriate licensing and accreditation and to follow industry standards.
Provides tree protections for physical damage, including considerations for roots. Prevents tree
planting unless it is in accordance with the ordinance. Requires approval for the use of tree-
stakes and guards. Specifies where slacklining is allowed on public trees and the necessary tree
protections. Outlines penalties for violations to the ordinance.
Defines heritage trees and outlines their maintenance and protections. Designates the Public
Works Department responsible for the enforcement of this chapter and addresses liability.
Title 15 Buildings and Construction adopts California Building Code and amends site plan
requirements to include the location and size of all trees, indicating trees to be preserved or
removed. Prohibits posting signs on street trees.
Title 16 Subdivisions requires plans and site maps for lot line adjustments to include all trees
on the property. Considers trees in design standards for lots and street layouts. Allows for
exceptions to the typical requirement for subdividing lots to reduce grading or tree removal.
Considers street trees in street improvements. Requires subdividers to grant land easements for
street trees if determined necessary. Defines “street tree”.
Title 17 Zoning Regulations requires trees as a pedestrian amenity in open space. Explains that
creek setbacks are not based on individual trees. Explains that lot areas do not include the area
within the dripline of heritage trees. Prohibits dead, decayed, infested (i.e., pests, including
vermin), diseased, overgrown trees on private property that are a public nuisance. Ensures street
trees are incorporated in street and right-of-way improvements when possible. Considers tree
removal as an option in reasonable accommodation for disabled persons in land use and zoning
regulations. Includes trees in the definition of “riparian vegetation”.
San Luis Obispo General Plan 2035
The General Plan is a document adopted by the City Council that considers the current, future
needs as well as available resources and provides the following:
Visions for San Luis Obispo’s future physical and economic development
Strategies and specific actions that will allow this vision to be accomplished
Bases for judging whether specific development proposals and public projects are in
harmony with community goals
Authorizes the design of projects that will enhance the character and safety of the
community and preserve environmental resources
Guides planning and implementing programs
The General Plan consists of eight elements, all of which pertain to the urban forest.
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81 Policy and Regulation
Land Use Element summarizes current community values to preserve the natural resources and
control urban growth. Calls attention to the greenbelt surrounding the City and requires
preservation of significant trees in the greenbelt. Highlights that the City works with partnering
land managers to protect significant trees located outside of city limits. Recommends trees and
groves of trees be used to differentiate the edge between developed areas and open lands.
Some of the Land Use Sustainability Policies have a central focus that directly relates to trees
and tree canopy, including:
Carbon sequestration (Policies: Climate Action, Natural Areas, and Green Space)
Urban cooling and shade (Urban Heat Effects)
Efficient landscapes with drought tolerant /native species, efficient irrigation, and
captured rainwater (Sustainable Design)
Long term tree planting program (Renew the Urban Forest)
An up-to-date master tree plan (Urban Forest)
Protecting the urban forest (Healthy Environment)
The Land Use element also calls to retain mature trees in the rights-of-way, cluster street trees
along scenic roadways to conserve views, encourage fruit trees in lieu of lawns or other plants
with high water use, and consider solar collector locations that minimize tree removal.
Circulation Element emphasizes creating streetscapes that incorporate street trees and
considers tree planting, maintenance, and retention. Expresses a preference for native species
with the desired characteristics. Addresses street tree placement along scenic roadways, and
encourages clusters of street trees to still allow for views. Promotes pedestrian and bike paths
that use trees as part of a buffer between pedestrians and traffic.
Housing Element supports neighborhood improvement projects, some of which incorporate
street trees. Considers trees and other natural features when assessing the environmental
constraints on residential development and estimated residential capacity.
Noise Element allows for landscape plantings
as a way to create an attractive noise
mitigation wall.
Safety Element presents policies and
programs to address hazardous trees and
emergency response.
Conservation and Open Space Element
describes San Luis Obispo’s natural resources
and emphasizes the importance of open space
for wildlife habitat and corridors. Notes that
trees are an essential component of the
habitats the City aims to preserve and expand
(i.e., oak woodland). Many of the goals,
policies, and programs covered in this element
impact trees, including the following:
“Significant trees, as determined by
the City Council upon the
recommendation of the Tree
Committee, Planning, or
Architectural Review Committee, are
those making substantial
contributions to natural habitat or to
the urban landscape due to their
species, size, or rarity.”
-Conservation and Open Space
Element of the General Plan
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Policy and Regulation 82
Protect significant trees
Continue the City’s Heritage tree program
Incorporate native plant species in landscapes
Minimize habitat disturbance during development, emphasize soil conservation
Follow integrated pest management practices to avoid the use of environmental toxins
Engage in area-wide planning efforts around environmental conservation (e.g., Habitat
Conservation Plans, U.S. Endangered Species Act)
Participate in environmental review
Incorporate trees around pedestrian and bike paths
Preserve and expand ecotones, wildlife corridors, and native vegetation
Require creek corridor setbacks that allow for riparian habitat, including trees
Engage the Tree Committee when implement tree preservation and planting programs
Promote wood reutilization through mulching, milling, or pulping
Support protected species and the conservation strategy (e.g., the conservation
strategy for monarch butterflies is to conserve groups of trees)
Parks and Recreation Element explains the existing park facilities. Mentions trees as amenities
in some of the City parks and considers landscaping a basic element of the parks. Recommends
acquiring new parkland, developing new parks, and increasing connectivity between parklands.
Highlights community and volunteer participation in park projects.
Water and Wastewater Element calls attention to the use of recycled water for irrigating
landscaping in parks, streetscapes, and medians as well as some types of landscaping on private
properties (e.g., homeowners associations, commercial, industrial, and business areas).
Introduces other water efficiency programs.
Climate Action Plan for Community Recovery
San Luis Obispo’s Climate Action Plan sets goals to reach carbon neutrality by 2035. During the
development of the Climate Action Plan, community workshops identified updating the City tree
list to focus on native species. The Plan is organized into 6 pillars, one of which is centered
around the urban forest.
Pillar 6: Natural Solutions focuses on ways to increase carbon sequestration. This pillar
introduces the City’s plan to develop their first Urban Forest Strategic Plan to guide tree
maintenance and planting. It also introduces 10 Tall: An Initiative to Plant 10,000 Trees in San
Luis Obispo by 2035 and supports this initiative’s goals to plant and maintain 10,000 new trees
by 2035. Although not a current goal, the City is looking into using the urban forest and other
carbon sequestration tools as carbon credits to offset greenhouse gas emissions.
This Pillar of the Climate Action Plan recognizes the urban forest for its contributions in
providing residents with benefits to mental health, cooling, stormwater management, watershed
health, and increased property values. It also highlights the role of the urban forest in
supporting local economic development through job creation. The community partnerships and
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83 Policy and Regulation
volunteer networks currently in place to help obtain urban forestry related goals are
documented.
This pillar sets the City’s intentions to continue routine tree maintenance and emergency
response for the current 20,000 trees in the inventory as well as the anticipated 10,000 new tree
plantings in existing vacant sites, open spaces, riparian areas, and parks. In total, the Plan
estimates 10,670 trees will be planted on public and private property. Another priority is riparian
restoration with a focus on native tree planting, the suggested species composition is included.
It calls for the use of an inventory management system to track progress.
This pillar includes equity considerations to identify the populations most vulnerable to extreme
heat and flooding and then use the urban forest to increase the benefits from trees in areas with
vulnerable populations.
2021-23 Financial Plan
The Financial Plan outlines the City’s two-year plan and the associated budget allocation for
core services and programs. In the current Financial Plan, the City Council, guided by community
input and advisory bodies, chose four areas to address the highest priority goals, these include:
Economic Recovery, Resiliency & Fiscal Sustainability
Diversity, Equity, & Inclusion
Housing & Homelessness
Climate Action, Open Space & Sustainable Transportation
The Financial Plan focuses on considering the financial resources needed to be successful in
implementing the goals adopted in the Climate Action Plan (e.g., carbon neutrality, preservation
of open space and the urban forest, and resilience planning). Tracking the number of public
trees that are maintained is included as a performance measure.
The Financial Plan also outlines the operating budget for General Fund programs that are
needed to continue Public Works operations, such as annual maintenance to the urban forest.
The staffing levels are reported, showing the Urban Forest program has lost staff (full time and
supplemental employees) in recent years, but contract services have increased.
Engineering Standards
Inspections at construction sites to assess progress also include an assessment for proper tree
protection.
Tree Protection Provides standards for tree protection during construction, including details on
protection fences, when it is appropriate to prune or attach something to trees being protected,
criteria for excavation, grading, trenching, and boring, and tree protection and monitoring plans.
Includes criteria for street trees and tree wells in the design standards for roadways. Mentions
permeable pavement as a way to increase aeration and water for tree roots in parking areas and
alternative, compact designs are allowed if it may result in saving a tree.
Provides standards for bioswale designs with and without trees. Includes the street trees master
list and street trees major lists. Illustrates and describes standards for tree wells and alternative
tree well covers.
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Policy and Regulation 84
Street Tree Planting Instructions and Requirements Illustrates and describes expectations for
tree planting, including tree quality, backfill material, tree size, type of tree, and planting
location, and materials (e.g., stakes, mulch, and guards). Requires inspections of the hole
dimensions prior to planting as well as the planted tree. Illustrates and describes standards for
installing drip irrigation and tree bubblers. Specifies using mulch at the base of trees.
Management and Performance Audit of the Public Works Department
The Management and Performance Audit categorized improvements to the Public Works
Department into six categories, all of which include recommendations that impact the urban
forest including the following:
Accountability focuses on clear and transparent direction. This category has broad
recommendations that relate to the urban forest, such as redirecting resources to
infrastructure maintenance and preservation as well as developing work planning and
scheduling systems.
Asset Management calls for a better understanding of community resources, such as
their condition and performance of the community tree resource.
Maintenance Management recommends implementing an information system that
can be used to track the inventory of all infrastructure and work activities as well as
setting annual work programs.
Administrative and Management focuses on implementing structural changes to the
department to increase efficiency, including changes to staffing levels and position
responsibilities. Specific recommendations are included for the Urban Forestry Division.
Preventative Maintenance of the Infrastructure recognizes the long-term benefits of
preventative maintenance to increase the useful lifespan of assets and reduce overall
costs.
Cost Effective Service Delivery highlights the cost savings associated with redesigning
staffing levels and duties, vehicle needs, and implementing managed competition for
contract work.
Estimating Urban Canopy Cover in San Luis Obispo
The tree canopy was determined for the urban reserve, which includes all of the core-built
features within the City boundary. This assessment uses 2012 aerial imagery to estimate the tree
canopy. When breaking down tree canopy by land use type, it showed that office properties and
residential areas have the highest canopy cover. Tree canopy varied slightly between the
residential density levels. The assessment found that tree canopy is not equally distributed
throughout the City and tree canopy varies nearly eight-fold between the land use categories
with the highest (Office) and lowest (Business Park) categories.
San Luis Obispo Creek Stormwater Resource Plan
Summarizes what is known about the watershed and recommends ways to improve watershed
health. Tree canopy is mentioned as a non-quantifiable benefit to buffer and shade aquatic
habitats. Tree planting is recognized as a way to control stormwater flow and water quality.
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85 Policy and Regulation
Green streets that increase water capture and reuse are identified as a priority need. Several
methods to increase water infiltration are listed including: bioretention, pervious pavements,
downspout disconnection, infiltration basins, and dry wells. Sets criteria to prioritize for green
streets projects (considers feasibility and ranks planned projects, public visibility, contributing
runoff and pollution, infiltration feasibility, proximity to critical habitat, and existing drainage
problems). Maps areas that generate greater stormwater runoff, which are largely areas with a
high proportion of roads.
Parks and Recreation Blueprint for the Future 2021-2041
Guiding themes for the SLO Parks and Recreation Blueprint plan include Stewardship and
Sustainability as well as Inclusion and Access. As part of the ‘Stewardship and Sustainability
goal,’ Parks aim to become carbon neutral and incorporate ‘low-allergen plants and trees’ (SLO
Parks). Additionally, as part of the ‘Inclusion and Access’ theme, Parks aims to create equal
access to green spaces for all. One of 25 new park projects, the Margarita Area plan, includes
park trees. At a 2018 pop-up event to gain community input, participants voted for trees as
being an important feature to be included at future parks. Trees were emphasized as important
to creating shaded play areas at future parks, as they not only contribute shade but a ‘distinctive
identity and sustainability’ (SLO Parks.) The park blueprints highlighted issues and future
planned improvements for each park in San Luis Obispo. Minimal shade was listed as an issue at
both Meadow Park Center and Laguna Lake Park. Shade could be increased at these parks with
tree planting.
The Blueprint document sets goals to:
Prepare a tree inventory for all the parks to inform future planting, maintenance needs,
and budget
Develop a master tree list to accommodate for climate change, allergen levels, and
drought tolerance
Develop a new work order management system in collaboration with Public Works to
assist staff in remaining up to date on maintenance tasks of various frequencies. This
includes managing natural assets like trees.
Resilient SLO
Resilient SLO is currently in the planning phase and this planning document aims to increase
resilience to the impacts of climate change.
Additional Planning Documents
In addition to these guiding documents, the City has developed Specific Area Plans that embed
the principles for tree maintenance that are presented in other guiding documents, such as the
General Plan and Engineering Standards.
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Policy and Regulation 86
Higuera Street then and now.
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87 Benchmark Community Survey
Benchmark Community Survey
An online survey was created for an initial assessment of community understanding,
appreciation, and future vision for San Luis Obispo’s urban forestry program and urban forest.
The survey was available on the City’s website, announced at City Council meeting and also
advertised with signs at parks and trailheads. Responses were collected between September 22
and October 21, 2021. In this one-month period, the online community survey received 644
responses from community members. The survey included 9 questions about community
members’ views on tree benefits, education and outreach, urban forest program operations, and
preferences for future plantings. The survey offered participants to expand on their answers and
provided space for thoughts and suggestions at the end. The complete survey and results are
available in Appendix E, and questions are summarized below.
While all the benefits of trees are important to consider, the preferences of a community for
certain benefits can be used by tree managers to select appropriate trees to further meet the
needs of the community. When asked why trees are important to the City, shading/cooling,
community character/aesthetics, wildlife habitat, and improving air quality were most frequently
chosen. However, a majority of the benefits offered in the survey were rated as important,
including connection with nature, improving quality of life, and reducing urban heat island
effects.
Figure 7: San Luis Obispo Community Member Opinions on the Most Important Benefits of Trees
61.8%58.5%
54.8%53.9%
46.6%46.4%
42.6%
35.3%
16.8%15.7%14.4%13.4%
8.5%6.4%4.5%2.2%1.7%1.4%Shading/coolingCommunity character/aestheticsWildlife habitatImproving air qualityConnection with natureQuality of lifeReducing urban heat islandeffectsGreenhouse gas reductionReducing energy needsReducing stormwater runoffReducing stressEnhancing pedestrian/bikecorridorsScreening/creating privacyIncreasing property valuesReducing health incidence/costOther (please specify)Increasing retail salesSafety/reducing crime0
50
100
150
200
250
300
350
400
450
BenefitNumber of ResponsesPage 591 of 748
Benchmark Community Survey 88
The survey indicated that environmental benefits from trees are relatively equal in importance to
the community. Respondents rated shading and cooling, greenhouse gas reduction, reducing
urban heat island effects, and improving air quality each around 20%. The lowest rated benefits
in level of importance were reducing stormwater runoff and wildlife habitat.
Figure 8: Community Member Opinions on the Most Important Environmental Benefit from Trees
Survey respondents were asked which socioeconomic benefits from trees they felt were most
important and given 11 options to choose from. The most important benefits according to the
survey, in descending order, were community character/aesthetics, quality of life, connection to
nature, and reducing energy needs which together received 85.1% of the votes.
Figure 9: Community Member Opinions on the Most Important Socioeconomic Benefit from Trees
22.1%21.3%20.2%
18.3%
13.4%
2.8%2.0%Greenhouse gasreductionShading/coolingReducing urbanheat island effectsImproving airqualityWildlife habitatReducingstormwater runoffOther (pleasespecify)0
20
40
60
80
100
120
140
160
Number of Responses32.8%
24.2%
16.6%
11.5%
3.6%3.1%2.3%2.0%1.7%1.1%0.6%0.5%Communitycharacter/aestheticsQuality of lifeConnection to natureReducing energy needsEnhancingpedestrian/bike corridorsReducing stressIncreasing propertyvaluesReducing healthincidence/costOther (please specify)Screening/creatingprivacyIncreasing retail salesSafety/reducing crime0
50
100
150
200
250
Number of ResponsesPage 592 of 748
89 Benchmark Community Survey
When asked where residents thought it was most important to plant trees, neighborhood
streets, parks, and open space were most important, but respondents also mentioned trees
should be planted everywhere. Respondents also emphasized the need for tree planting in
medians along arterial roads, many of which lack greenery or canopy and feel like ‘freeways’ and
to use these trees as traffic-calming devices. While locations such as schools, parking lots, and
buffer zones between freeways and neighborhoods were not choices, respondents volunteered
that these as important locations for further planting.
Figure 10: Community Member Opinions on Where it is Most Important to Plant More Trees
Private property planting is an important aspect of growing urban forest canopy and will be an
important factor in increasing canopy with San Luis Obispo. When asked what survey
respondents thought were the best ways to encourage private property planting, the top three
responses were to offer a free or low-cost tree, to offer a rebate on water bills, and to have a
rebate for purchased trees. Survey respondents also had other recommendations, such as
having a lawn sign or decal to show they are a part of the 10,000 Trees initiative, to hold a photo
contest, and to have a tax incentive.
Figure 11: Community Member Opinions on Encouraging Tree Planting on Private Property
77.3%
54.5%
40.9%
34.7%
29.3%28.9%
7.6%
Neighborhood
streets
Parks Open space Medians Retail areas Arterial roads Other (please
specify)
0
100
200
300
400
500
600
Number of Responses72.0%
61.2%
49.4%45.0%
34.7%
7.0%
Free or low‐cost
tree
Rebate on water
bill
Rebate on
purchased tree
Tree species and
site selection
information
Community tree
planting event
Other (please
specify)
0
50
100
150
200
250
300
350
400
450
500
Number of ResponsesPage 593 of 748
Benchmark Community Survey 90
Overall, survey respondents were fairly aware of the urban forest program and its operations in
the City. About 70% of respondents had seen city crews working on trees, and about 20% of
respondents had used the City website or called about tree information. However, 25% of
respondents were not aware that there was an urban forest program. Some of the respondents
had connections with the Tree Committee, heard about the program through ECOSLO, had
taken an Urban Forestry class at Cal Poly, or had personally planted trees at the Arbor Day
events.
Figure 12: Community Member Awareness and Interactions with the Urban Forestry Program
Residents were generally satisfied with the level of care given to community trees. Most were
‘somewhat satisfied’ (38.4%) and neutral or no opinion (32.1%). A total of 16.8% of respondents
were either somewhat dissatisfied or completely dissatisfied with the level of tree care.
Figure 13: Community Member Opinions on the Level of Care Provided for Community Trees
Most respondents were not sure whether urban forest services and programs are equally
accessible to all residents (63.3%). About 20% of respondents said that they are not equally
accessible, whereas 16.5% answered that urban forest services are equally accessible.
70.3%
52.8%
25.4%
20.4%
15.6%
9.0%8.3%
I have seen City
crews working
on trees
I was aware
that the City
responds to
tree
emergencies
I did not know
the City had a
program to care
for trees
I have used the
City website or
called for tree
information
I have read an
article in The
New Times or
The San Luis
Obispo Tribune
about trees
Other (please
specify)
I have
volunteered at
tree related
events
0
50
100
150
200
250
300
350
400
450
Number of Responses38.4%
32.1%
12.8%11.1%
5.7%
Somewhat satisfied Neutral Completely satisfied Somewhat dissatisfied Completely
dissatisfied
0
50
100
150
200
250
Number of ResponsesPage 594 of 748
91 Benchmark Community Survey
Figure 14: Community Member Opinions on Whether Urban Forest Services and Programs are Equally
Accessible to all Residents
SLO survey respondents were interested in most topics of education and outreach presented in
the survey. Most respondents were interested in information on a tree list and about which trees
to plant in the City. They also indicated education and outreach regarding irrigation and
watering during a drought as an important topic. Survey respondents also commented that
education could be provided in public schools and requested guidance and education regarding
tree planting for greenhouse gas reduction.
Figure 15: Community Member Opinions on Topics of Education and Outreach of Interest
63.3%
20.3%
16.5%
Not sure No Yes
0
50
100
150
200
250
300
350
400
450
Number of Responses84.6%
73.9%
47.7%46.5%
28.4%
6.5%
Tree list/what tree
should I plant in
San Luis Obispo
Irrigation/watering
during drought
How to plant a
tree
Benefits of trees How to hire a tree
care professional
Other (please
specify)
0
100
200
300
400
500
600
Number of ResponsesPage 595 of 748
Benchmark Community Survey 92
Page 596 of 748
93 Analysis of Sustainability Indicators
Analysis of Sustainability Indicators
The Sustainability Indicators is a tool based on the Characteristics of Urban Forest Sustainability
as defined in the 1997 Journal of Arboriculture article “A Model of Urban Forest Sustainability”,
which describes specific criteria that can be used in conjunction with measurable indicators to
evaluate sustainability (Clark et al. 1997). To identify goals and areas where the urban forestry
program can be improved, Urban Forest Services can regularly assess, evaluate, and indicate the
current performance levels of the urban forest through the Sustainability Indicators.
While the Sustainability Indicators is a useful tool for assessing the current status of an urban
forest program, it does not necessarily provide a comprehensive review of all the areas in which
a program could be improved. In the case of San Luis Obispo, not all of the indicator categories
are applicable to the Public Works Department. The Sustainability Indicators do provide an
opportunity for Urban Forest Services to benchmark their current conditions and understand
how they can be improved to meet industry recommendations and then establish performance
measures to improve the effectiveness of their management approach (Kenney, et al 2011). The
criteria for the Sustainability Indicators were used as a reference to assess the current urban
forestry practices in San Luis Obispo and proved the framework for describing what current
urban forest management looks like and a step to advance urban forest management. For a
detailed report of the results of the assessment, refer to Appendix D.
The Trees
Among the three performance areas, The Trees is where San Luis Obispo currently has the lowest
performance. The categories relating to the tree inventory, such as Age of Trees and Condition
of Publicly Owned Trees have low to medium ratings because most community trees are not
receiving routine maintenance nor are their attributes regularly updated in an inventory system.
Trees in the downtown core are the exception. Downtown trees are regularly maintained, they
are also monitored for structural defects and trees are removed and replaced as needed. San
Luis Obispo is moving toward proactive maintenance for trees along streets, in parks, rights-of-
way, and at City facilities. As work is completed, inventory data specifications such as tree
condition, defects, and any necessary maintenance tasks to address risk will be updated. As part
of the next phase in the urban forest planning process, the City intends to update the entire tree
inventory, with the exception of trees located in open spaces.
Location of Canopy and Trees on Private Property were categories of low performance for San
Luis Obispo. These categories are used to assess whether a community has an equitable
distribution of canopy across the community and if the extent and health of canopy on private
property is well known. Currently, urban forest managers have access to limited, outdated
information on tree canopy in the built areas of the community. Furthermore, the community is
currently experiencing a considerable amount of infill development as a result of state housing
mandates. Like many California communities, development will continue to put pressure on
urban forest growth and result in additional competition for space for trees. Some development
plans omit setbacks, taking away already limited space for trees. As a result, the extent and
location of tree canopy is changing quickly. To progress in this area, the City should conduct a
land cover and tree canopy assessment to determine the amount and distribution of tree
Page 597 of 748
Analysis of Sustainability Indicators 94
canopy citywide and use this information to determine areas that are in the most need of
additional tree preservation and planting efforts.
Table 2: Sustainable Indicators
Indicators of a Sustainable Urban Forest
Assessed
Performance Level
Low Medium High
The
Trees
Urban Tree Canopy
Equitable Distribution
Size/Age Distribution
Condition of Public Trees ‐ Streets, Parks
Condition of Public Trees ‐ Natural Areas n/a n/a n/a
Trees on Private Property
Species Diversity
Suitability
Soil Volume
The Players
Neighborhood Action
Large Private & Institutional Landholder
Involvement
Green Industry Involvement
City Department/Agency Cooperation
Funder Engagement
Utility Engagement
State Engagement
Public Awareness
Regional Collaboration
The
Management
Approach
Tree Inventory
Canopy Assessment
Management Plan
Risk Management Program
Maintenance of Publicly‐Owned Trees (ROWs)
Maintenance of Publicly‐Owned Natural Areas n/a n/a n/a
Planting Program
Tree Protection Policy
City Staffing and Equipment
Funding
Disaster Preparedness & Response
Communications
Totals 9.5 15.5 3.5
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95 Analysis of Sustainability Indicators
Although San Luis Obispo has not set canopy goals, community members initiated an
aggressive tree planting initiative. While the majority of the trees planted as part of this initiative
will occur in open spaces, it calls for a fully stocked inventory in built areas. Urban forest
Services, in partnership with ECOSLO, is not on a trajectory to achieve a fully stocked inventory
along streets, in parks, rights-of-way, and at City facilities by 2035. To meet this goal, Urban
Forest Services will need to prioritize tree planting through the development and
implementation of planting plans that not only outline planting sites and timeframes, but also
the roles of Urban Forest Services, ECOSLO, and contractors.
In The Trees indicator category, San Luis Obispo’s strongest areas of performance is in Species
Diversity. As of 2008, the most abundant species, coast live oak (Quercus agrifolia), is native to
the region and represents 10% of the entire population. All other species represent 5% or less of
the overall population. Incorporating as much species diversity into an urban population as
possible is hugely important for a sustainable and resilient urban forest, especially considering
current and emerging pests and disease threats. Although Urban Forest Services is likely still
meeting expectations in this area, striving for even greater diversity is well-advised.
The Players
The Players is a performance area where Urban Forest Services is consistently ranking in the
medium category. Three categories were assessed as low to medium and could be improved to
advance the urban forestry program, including large private and institutional landholder
involvement, utility engagement, and funder engagement. Greater interaction with external
groups could promote Urban Forest Service’s goals to provide proactive maintenance to all
along streets, in parks, rights-of-way and at City facilities. Currently, all of the Urban Forest
Service’s funding comes from the General Fund. While the community is currently supportive of
urban forest goals, it is still important to secure adequate and sustainable funding.
Discussion with Urban Forest Services and other urban forest partners revealed that
communication between teams is generally good. Collaborations are often on a project-specific
basis and most frequently revolve around emergency response. While communication avenues
are in place, the current workload hinders Urban Forest Service’s ability to be a stronger
collaborator toward shared visions for the urban forest. One area in particular, development
review, has fallen by the wayside due to the recent increase in development and the lack of a
review arborist. Development proposals often result in the loss of mature trees which is a
primary concern of community members that feel the City is not doing enough to preserve the
urban forest.
As a whole, the community has a great appreciation for trees and a strong desire to support tree
canopy through the preservation of existing trees and increased planting efforts. In fact, the
community was integral to the robust tree planting initiative outlined in the Climate Action Plan
and recognizes the urban forest for its role in providing a number of benefits to health and
welfare of the community. Urban Forest Services relies on their nonprofit partner, ECOSLO, to
coordinate with volunteers for tree planting and care in urban areas. While coordinated
neighborhood action is limited to the Downtown Foresters and Downtown Ambassadors, many
residents volunteer to support the urban forest.
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Analysis of Sustainability Indicators 96
The Management Approach
Finally, The Management Approach is the area identified by the assessment to have the most
criteria where the urban forestry program is performing at medium to high levels. The
community’s tree protection policy is an area of high performance for the program, as the policy
not only protects benefits derived from trees on public property, but also those on private
property. While this is a significant achievement for the program, this area can further be
strengthened through educational campaigns to increase community awareness for the
ordinance and expanded enforcement to protect the resource and the benefits derived from all
trees.
Recent retirements and general staff attrition have strained staffing levels and at the current
level (two staff) is inadequate to effectively manage the resource and the urban forestry
program. As a result, the program is performing at a medium level in the City Staffing and
Equipment categories. This area has numerous opportunities for improvement, as the intention
is to increase staffing levels and expand the use of contractors to provide regular and routine
maintenance for all community trees. Improvements in these two categories could also result in
improvements in other areas, such as Risk Management, which was ranked low. To enhance
performance in this category, Urban Forest Services should conduct annual inspections and
proactively address hazards.
Tree Inventory and Canopy Assessment are areas of medium performance. Currently, the
program does not have a comprehensive and complete GIS-based community tree inventory
nor an urban forest canopy assessment based on high-resolution tree canopy imagery. Updates
to the inventory, will provide greater knowledge about the community tree resource. Further
study and assessment of overall canopy cover could assist in community-wide planting projects,
like the 10,000 Trees initiative. Both an inventory and a canopy assessment would aid in the
development of management plan, which would define long-term maintenance schedules,
planting plans that consider the strategic placement of trees to maximize benefits. The
implementation of a management plan would further advance the program in the Management
Plan category. These would give the urban forest program a greater understanding of the
current resource, benchmark canopy levels, and help determine progress on their planting
initiatives.
“Progressive cities like ours should lead the way in tempering our desire to
provide additional housing with the restraint necessary to keep from destroying
the very reason we love our community.”
-Survey Respondent
Page 600 of 748
97 Conclusion
Conclusion
The information gathered during this review of the urban forestry program provided an initial
assessment of the challenges and opportunities for San Luis Obispo’s urban forest. Further
exploration of urban forestry partnerships, community engagement, and assessment of the
community tree resource and overall canopy will be critical for the development of a
comprehensive urban forest strategic plan. The initial review of tree care operations, staffing,
policies and guiding documents, and community feedback have emphasized a critical need for
improvements in the care for the community tree resource.
Challenges with staffing have resulted in long-term delays of routine care for trees in most areas
of the community, which prior to 2019, were receiving care every 8 to 10 years. With the
implementation of contractor services to provide routine care in 2021, Urban Forest Services is
moving toward a cyclical maintenance cycle for the estimated 20,000 trees along streets, in
parks, public rights-of-way, and at City facilities. Tree maintenance in the downtown core is a
priority and these trees receive regular care, but all other maintenance is reactionary, driven by
responding to service requests, work orders, or concerns. Ideally, Urban Forest Services would
have all trees on a predictable pruning schedule, considering species that require more frequent
maintenance (such as palms and Ficus spp.). Many of the concerns around establishing more
proactive maintenance can be addressed by (1) contracting out cycle pruning, (2) reinstating an
in-house crew to address service requests and work orders, and (3) developing comprehensive
schedules and work plans that consider routine maintenance needs, rotation schedules, and the
time required to complete necessary maintenance (e.g., average time to complete maintenance).
Urban forest partners are critical to meeting the long-term goals for the urban forest. While
Urban Forest Services is responsible for the maintenance of trees in the built areas of the
community, staff in the Parks and Recreation Department and Administration Department care
for a large portion of the urban forest and provide critical visioning and goals setting. The City’s
partnership with ECOSLO has been integral to tree planting and establishment. Over the past 2
years, approximately half of the tree plantings in the urban areas of San Luis Obispo have been
planted by volunteers through this program each year. Departments collaborate to effectively
address storm response. Through open communication and shared equipment, these situations
can be quickly addressed.
Prior to 2008, it was standard procedure that the inventory was updated as work was completed.
At the time, the species diversity, age distribution, and condition ratings indicated a diverse,
ideally aged resource in fair or better condition. Since that time, the inventory has not stayed
current and therefore the current structure and health of the community tree resource is largely
unknown. An up-to-date, regularly maintained inventory is key to understanding the tree
resource in real time, which is especially helpful for assisting staff in determining and prioritizing
tree care and tree planting. Urban Forest Services recognizes the importance of having a current
inventory and there are efforts underway to update the inventory by completing a
comprehensive inventory. The updated data specifications for the community tree resource will
provide the necessary information to develop a plan for maintenance and identify areas where
tree planting is needed to replace trees that have previously been removed or to plan for the
succession of an aging and maturing trees, especially in the downtown core.
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Conclusion 98
Responses to an online community survey revealed that trees are greatly appreciated by
residents and are seen as a valuable part of the community’s identity. Respondents noted that
trees are most appreciated for providing shade and contributing positively to the overall
community aesthetics. Through comments, respondents voluntarily expressed great concern
over the loss of mature trees as a result of the recent increase in development.
A strength of San Luis Obispo’s urban forestry program is that there is a strong tree protection
ordinance. The ordinance not only prohibits the removal and pruning of public trees, but also
trees on private property. Furthermore, if trees are removed, those trees must be replaced with a
sufficient number of trees as determined by the ordinance, Tree Committee, or City Arborist.
While mitigation planting can help offset some of the benefits that are lost from mature trees
that are removed, sufficiently replacing mature trees with mitigation plantings takes decades, as
trees planted as part of mitigation efforts will take a long time to achieve the same level of
canopy as the trees that were removed. Although mitigations are required per Municipal Code,
not all large statured trees are being replaced with species of similar stature. As San Luis Obispo
continues to undergo infill development and potentially expand, undoubtedly trees will continue
to be affected. Feedback from stakeholders and the community suggest that expanded
education to the community about the tree protection ordinance, coupled with expanded
development review, and clarification of the role of the Tree Committee will be critical to
protecting large, mature trees and preserving tree canopy.
From this assessment of the urban forestry program, it is clear that further study and
examination of urban forest partnerships and community engagement are needed to not only
improve the urban forestry program, but also to develop a comprehensive urban forest strategic
plan, which will ensure that the necessary resources are in place to care for the entire
community tree resource and provide a long-term vision for the urban forest. In order to
develop a comprehensive urban forest strategic plan future planning phases should include:
A comprehensive tree inventory that is regularly updated by all urban forest partners
A Resource Analysis that benchmarks the composition, benefits, and the value of the
community tree resource
Mapping of the existing canopy and summarize results through a Canopy and Land
Cover Assessment
Management plans and budget needs to maintain trees on a 6-year cycle
Further engagement of applicable stakeholders to identify and build consensus for
solutions to challenges and opportunities that were identified for trees managed by
Urban Forest Services in the summary report
Consideration for challenges and opportunities for the remainder of the urban forest,
including trees maintained by other departments in open space, natural areas, and
riparian areas, private landowners, and other government agencies
Robust community engagement
Additional discussions with urban forest partners and the community will be required to
determine the path forward to re-enacting the high-performing urban forestry program with
restoring service to the level prior to 2019. Discussions with Public Works and urban forest
Page 602 of 748
99 Conclusion
partners coupled with a review of policies and guiding documents have revealed great concern
over the need to provide a greater level of care to San Luis Obispo’s community trees. With
adequate staffing levels and continued contracted maintenance, San Luis Obispo’s urban
forestry program will be on the right track to re-enact a high-performing urban forestry
program, considering:
Secured funding for increased staffing and contract maintenance
Ambitious tree planting initiatives
Collaborative avenues in place amongst Departments
Engaged, passionate, and supportive community members
Progress in increasing the level of performance in meeting Sustainability Indicators
Page 603 of 748
Conclusion 100
Page 604 of 748
101 Appendix A: References
Appendix A: References
Bastin J-F, Clark E, Elliott T, Hart S, van den Hoogen J, Hordijk I, et al. (2019) Understanding
climate change from a global analysis of city analogues. PLoS ONE 14(7): e0217592.
https://doi.org/10.1371/journal.pone.0217592
Bond, J. and Buchanan, A. 2006. Best Management Practices Tree Inventories. International
Society of Arboriculture. Champaign, IL.
California Legislative Information. 2021. Senate Bill #9. Chapter 162 of Government Code
Regarding Land Use. Retrieved from:
https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202120220SB9
California Oak Mortality Task Force. 2020. Maps & Visual Media. Retrieved from:
http://www.suddenoakdeath.org/
California Office of Environmental Health Hazard Assessment. 2021. Traffic density. Retrieved
from: https://oehha.ca.gov/calenviroscreen/indicator/traffic-density
City of San Luis Obispo. 2021. Fire Department: About Us. Retrieved from:
https://www.slocity.org/government/department-directory/fire-department/about-us
Cal Poly. 2020. Cal Poly Honored Again by Arbor Day Foundation as a Tree Campus USA.
Retrieved from: https://calpolynews.calpoly.edu/news_releases/2020/april/arbor_day
Carter, J. G., Cavan, G., Connelly, A., Guy, S., Handley, J., & Kazmierczak, A. (2015). Climate change
and the city: Building capacity for urban adaptation. Progress in Planning, 95, 1-66.
Clark et al. 1997. A Model of Urban Forest Sustainability. Journal of Arboriculture 23(1). Retrieved
from: https://naturewithin.info/Policy/ClarkSstnabltyModel.pdf
City of San Luis Obispo. N.d. Sustainable Growth Management. Retrieved from:
https://www.slocity.org/home/showpublisheddocument/21740/636734813174500000
City of San Luis Obispo Fire Department. 2021. About us. Retrieved from:
https://www.slocity.org/government/department-directory/fire-department/about-us
Clark, J.R., Matheny, N.P., Cross, G., Wake, V. 1997. A Model of Urban Forest Sustainability. J
Arbor 23(1):17-30.
Daugherty, M. and Hung, K. n.d. Sudden Oak Death. University of California Riverside Center for
Invasive Species Research. https://cisr.ucr.edu/invasive-species/sudden-oak-death
Day, S. D., Wiseman, P. E., Dickinson, S. B., & Harris, J. R. (2010). Contemporary concepts of root
system architecture of urban trees. Arboriculture & Urban Forestry, 36(4), 149-159.
Downtown SLO. 2021. Downtown San Luis Obispo. Retrieved from: https://downtownslo.com/
Page 605 of 748
Appendix A: References 102
EDDMapS. 2021. Early Detection & Distribution Mapping System. The University of Georgia —
Center for Invasive Species and Ecosystem Health. Retrieved from http://www.eddmaps.org/
Eskalen, A. Kabashima, J., and Dimson, M. 2017. Invasive Shot Hole Borer and Fusarium Dieback
Field Guide. Identifying signs and symptoms of the Polyphagous and Kuroshio Shot Hole Borer.
University of California, Agriculture and Natural Resources. Retrieved from:
https://ucanr.edu/sites/eskalenlab/files/290780.pdf
Grafton-Cardwel, Daugherty, Jetter, & Johnson. 2019. ACP/HLB Distribution and Management.
University of California, Division of Agriculture and Natural Resources. Retrieved from:
https://ucanr.edu/sites/ACP/
Janowiak, Maria K.; Brandt, Leslie A.; Wolf, Kathleen L.; Brady, Mattison; Darling, Lindsay; Lewis,
Abigail Derby; Fahey, Robert T.; Giesting, Kristen; Hall, Eboni; Henry, Molly; Hughes, Maise;
Miesbauer, Jason W.; Marcinkowski, Kailey; Ontl, Todd; Rutledge, Annamarie; Scott, Lydia;
Swanston, Christopher W. 2021. Climate adaptation actions for urban forests and human health.
Gen. Tech. Rep. NRS-203. Madison, WI: U.S. Department of Agriculture, Forest Service, Northern
Research Station. 115 p. https://doi.org/10.2737/NRS-GTR-203
Johnson, P. 2021. Building out: The city of SLO has enough housing under construction to reach
its growth cap ahead of schedule. New Times SLO. Retrieved from:
https://www.newtimesslo.com/sanluisobispo/building-out-the-city-of-slo-has-enough-housing-
under-construction-to-reach-its-growth-cap-ahead-of-schedule/Content?oid=10949205
Kenney, W. A., van Wassenaer, P. J., & Satel, A. L. 2011. Criteria and indicators for strategic urban
forest planning and management. Arboriculture & Urban Forestry, 37(3), 108-117.
Management and Performance Audit of the Public Works Department. 2011.
Nessen, K. 2012. Estimating urban canopy cover in San Luis Obispo. PDF power point
presentation.
Richards, N.A. 1982/83. Diversity and Stability in a Street Tree Population. Urban Ecology. 7:159-
171.
Santamour, F. 1990. Trees for urban planting: Diversity, uniformity, and common sense.
Proceedings of the 7th Conference of Metropolitan Tree Improvement Alliance. 7.
Senate Bills 8. Housing Crisis Act of 2019.
https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202120220SB8
Senate Bill 9. Housing development: approvals.
https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202120220SB9
Senate Bill 10. Planning and zoning: housing development: density.
https://leginfo.legislature.ca.gov/faces/billNavClient.xhtml?bill_id=202120220SB10
Page 606 of 748
103 Appendix A: References
SLO City. n.d. Sustainable Growth Management. Retrieved from
https://www.slocity.org/home/showpublisheddocument/21740/636734813174500000
Umeda, C., Eskalen, A., and Paine, T. D. 2016. Polyphagous shot hole borer and Fusarium dieback
in California. Insects and Diseases of Mediterranean Forest Systems (pp. 757-767). Springer, Cham.
University of California. 2021. Pest Overview: Invasive Shot Hole Borers. Retrieved from:
https://ucanr.edu/sites/pshb/pest-overview/#about-the-beetles
Wiley, Hannah. 2021. “More duplexes. Gavin Newsom signs bills aimed at creating more
affordable housing in California.” Retrieved from: https://www.sacbee.com/news/politics-
government/capitol-alert/article254302493.html
Wiseman, P. E., & Raupp, R. J. 2016. Best Management Practices. Integrated Pest Management,
2nd ed. International Society of Arboriculture, Champaign, IL.
Zhu, K., Woodall, C. W., & Clark, J.S. 2012. Failure to migrate: lack of tree range expansion in
response to climate change. Global Change Biology, 18(3), 1042-1052.
Page 607 of 748
Appendix B: Industry Standards 104
Appendix B: Industry Standards
ANSI Z133 Safety Standard, 2017
Reviews general safety, electrical hazards, use of vehicles and mobile equipment, portable power
hand tools, hand tools and ladders, climbing, and work procedures.
ANSI A300
ANSI A300 standards represent the industry consensus on performing tree care operations. The
standards can be used to prepare tree care contract specifications.
ANSI A300 Pruning Standard-Part 1, 2017
ANSI A300 Soil Management-Part 2, 2011
ANSI A300 Support Systems Standard-Part 3, 2013
ANSI A300 Construction Management Standard-Part 5, 2012
ANSI A300 Transplanting Standard-Part 6, 2012
ANSI A300 Integrated Vegetation Management Standard-Part 7,2012
ANSI A300 Root Management Standard-Part 8, 2013
ANSI A300 Tree Risk Assessment Standard a Tree Failure-Part 9, 2017
ANSI A300 Integrated Pest Management-Part 10, 2016
Includes guidelines for implementing IPM programs, including standards for Integrated Pest
Management, IPM Practices, tools and equipment, and definition.
Best Management Practices (BMPs)
Integrated Pest Management, Second Edition, P. Eric Wiseman and Michael J. Raupp, 2016
Provides a comprehensive overview of the basic definitions, concepts, and practices that pertain
to landscape Integrated Pest Management (IPM). The publication provides specific information
for designing, planning, and implementing an IPM program as part of a comprehensive Plant
Health Care (PHC) management system, including topics such as:
IPM Concepts and Definitions
Action Thresholds
Monitoring Tools and Techniques
Preventive Tactics
Control Tactics
Documentation and Recordkeeping
Integrated Vegetation Management, Second Edition, Randall H. Miller, 2014
A guide to the selection and application of methods and techniques for vegetation control for
electric rights-of-way projects and gas pipeline rights-of-way. Topics included: safety, site
evaluations, action thresholds, evaluation, and selection of control methods, implementing
Page 608 of 748
105 Appendix B: Industry Standards
control methods, monitoring treatment and quality assurance, environmental protection, tree
pruning and removal, and a glossary of terms.
Managing Trees During Construction, Second Edition, Kelby Fite and E. Thomas Smiley,
2016
Describes tree conservation and preservation practices that help to protect selected trees
throughout the construction planning and development process so that they will continue to
provide benefits for decades after site disturbance, including planning phase, design phase, pre-
construction phase, construction phase, and post-construction phase.
Root Management, Larry Costello, Gary Watson, and Tom Smiley, 2017
Recommended practices for inspecting, pruning, and directing the roots of trees in urban
environments to promote their longevity, while minimizing infrastructure conflicts.
Special companion publication to the ANSI A300 Part 8: Tree, Shrub, and Other Woody Plant
Management–Standard Practices (Root Management)
Tree Planting, Second Edition, Gary Watson, 2014
Provides processes for tree planting, including site and species selection, planting practices,
post-planting pruning, and early tree care. Other topics included are time of planting, nursery
stock: types, selection, and handling, preparing the planting hole, planting practices, root loss
and new root growth, redevelopment of root structure, pruning, palms, after planting, final
inspection, and a glossary of terms.
Tree Inventories, Second Edition, Jerry Bond, 2013
Provides considerations for managing large numbers of trees considered as individuals rather
than groups and serves as a guide for making informed decisions that align with inventory goals
with needs and resources, including inventory goals and objectives, benefits and costs, types,
work specifications, and maintaining inventory quality.
Tree Risk Assessment, Second Edition, E. Thomas Smiley, Nelda Matheny, and Sharon Lilly,
2017
A guide for assessing tree risk as accurately and consistently as possible, to evaluate that risk,
and to recommend measures that achieve an acceptable level of risk, including topics: risk
assessment basics, levels and scope of tree risk assessment, assessing targets, sites, and trees,
tree risk categorization, risk mitigation: preventive and remedial actions, risk reporting, tree
related conflicts that can be a source of risk, loads on trees, structural defects and conditions
that affect likelihood of failure, response growth, description of selected types of advanced tree
risk assessments.
Tree Shrub Fertilization, Third Edition, E. Thomas Smiley, Sharon Lilly, and Patrick Kelsey,
2013
Aides in the selection and application of fertilizers for trees and shrubs, including: Essential
elements, determining goals and objectives of fertilization, soil testing and plan analysis,
fertilizer selection, timing, application, application area, rates, storage and handling of fertilizer,
sample fertilizer contract for commercial/ municipal clients.
Page 609 of 748
Appendix B: Industry Standards 106
Soil Management, Bryant Scharenbroch, E. Thomas Smiley, and Wes Kocher, 2014
Focuses on the protection and restoration of soil quality that support trees and shrubs in the
urban environment, including goals of soil management, assessment, sampling, and analysis,
modifications and amendments, tillage, conservation, and a glossary of terms.
Utility Pruning of Trees, Geoffrey P. Kempter, 2004
Describes the current best practices in utility tree pruning based on scientific research and
proven methodology for the safe and reliable delivery of utility services, while preventing
unnecessary injury to trees. An overview of safety, tools, and equipment, pruning methods and
practices, and emergency restoration are included.
Page 610 of 748
107 Appendix C: Estimated Time on Services
Appendix C: Estimated Time on Services
Table 3: Tasks and Estimated Time Spent by Urban Forest Services Staff
Urban Forest Services Task Hours Allocated Each Week
Asset Management and Maintenance
Pruning in ROW, Parks, and City Facilities 60‐90
Commemorative Grove planting and maintenance 5
Commemorative Grove mowing and watering 15a
Young tree care and watering 40
Emergency response 10‐15
Citizen complaint and correspondences 10
Inventory management, including private heritage trees 5‐10
Removal applications 5‐15
Tree planting in empty wells 1‐2b
Pest management 20d
Coordination for hardscape repairs/CIP Projects 1‐3
Contract monitoring 5‐20
Iron grate services 0‐5
Code Enforcement
Illegal removal enforcement 2‐5
Vegetation in the ROW enforcement 1‐2
Inspect tree planting 0‐2
Mitigation planting enforcement 0‐2
Regulatory Framework
Development review 2‐6
Development inspections 2‐4
Regulatory framework for public and private trees 0‐2
Education and Outreach
Education and outreach 0‐10c
Arbor Day celebration 50‐60d,e
Advisory Roles
Tree Committee liaison 3‐5
Other
Clearance and visibility on private trees 0‐1
aDuring summer and/or drought
bCity staff time (does not include contractor time)
cSporadic; can vary
dAnnual hours
e3-4 staff a whole month to prepare
Page 611 of 748
Appendix D: Sustainability Indicators 108
Appendix D: Sustainability Indicators
Table 4: The Trees
THE TREES
Indicators of a
Sustainable Urban
Forest
Overall Objective or
Industry Standard
Performance Levels
Low Medium High
Urban Tree Canopy
Achieve the desired tree
canopy cover according
to goals set for the entire
city and neighborhoods.
Alternatively, achieve
75% of the total canopy
possible for the entire
city and in each
neighborhood.
Canopy is
decreasing.
‐ and/or ‐
No canopy goals
have been set.
Canopy is not
dropping, but not on
a trajectory to
achieve the
established goal.
Canopy goal is
achieved, or well on
the way to
achievement.
Canopy goals have not been set, but the community has an
aggressive tree planting initiative.
Location of Canopy
(Equitable Distribution)
Achieve low variation
between tree canopy and
equity factors citywide by
neighborhood. Ensure
that the benefits of tree
canopy are available to
all, especially for those
most affected by these
benefits.
Tree planting and
public outreach
and education is
not determined by
tree canopy cover
or benefits.
Tree planting and
public outreach and
education is focused
on neighborhoods
with low tree
canopy.
Tree planting and
public outreach and
education is focused
on neighborhoods
with low tree
canopy and a high
need for tree
benefits.
Tree plantings are ongoing through a partnership with ECOSLO.
Age of Trees (Size and
Age Distribution)
Establish a diverse‐aged
population of public trees
across the entire city and
for each neighborhood.
Ideal standard:
0‐8" DBH: 40%
9‐17" DBH: 30%
18‐24" DBH: 20%
Over 24" DBH: 10%
No current
information is
available on size.
‐ OR ‐
Age distribution is
not proportionally
distributed across
size classes at the
City level.
Size classes are
evenly distributed at
the City level,
though unevenly
distributed at the
neighborhood level.
Age distribution is
generally aligned
with the ideal
standard diameter
classes at the
neighborhood level.
Current information on age distribution is not available, but the
outdated inventory data (2008) shows a nearly ideal distribution.
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109 Appendix D: Sustainability Indicators
Condition of Publicly
Owned Trees (trees
managed intensively)
Possess a detailed
understanding of tree
condition and potential
risk of all intensively‐
managed, publicly‐owned
trees. This information is
used to direct
maintenance actions.
No current
information is
available on tree
condition or risk.
Information from a
partial or sample or
inventory is used to
assess tree condition
and risk.
Information from a
current, GIS‐based,
100% complete
public tree inventory
is used to indicate
tree condition and
risk.
A partial inventory is regularly monitored, it includes street trees in
the Downtown core.
Condition of Publicly‐
Owned Natural Areas
(trees managed
extensively)
Possess a detailed
understanding of the
ecological structure and
function of all publicly‐
owned natural areas
(such as woodlands,
ravines, stream corridors,
etc.), as well as usage
patterns.
No current
information is
available on tree
condition or risk.
Publicly‐owned
natural areas are
identified in a
sample‐based
"natural areas
survey" or similar
data.
Information from a
current, GIS‐based,
100% complete
natural areas survey
is utilized to
document ecological
structure and
function, as well as
usage patterns.
n/a
Trees on Private
Property
Possess a solid
understanding of the
extent, location, and
general condition of trees
on private lands.
No data is available
on private trees.
Current tree canopy
assessment reflects
basic information
(location) of both
public and private
canopy combined.
Detailed information
available on private
trees. Ex. bottom‐up
sample‐based
assessment of trees.
The location and health of the canopy on private property is largely
unknown.
Diversity
Establish a genetically
diverse population of
publicly‐owned trees
across the entire city and
for each neighborhood.
Tree populations should
be comprised of no more
than 30% of any family,
20% of any genus, or 10%
of any species.
No current
information is
available on
species.
‐ OR ‐
Fewer than five
species dominate
the entire tree
population
citywide.
No species
represents more
than 20% of the
entire tree
population citywide.
No species
represents more
than 10% of the
entire tree
population citywide.
The most abundant species represents 10% of the population. All
other species are less than 5% of the population.
Page 613 of 748
Appendix D: Sustainability Indicators 110
Climate
Resilience/Suitability
Establish a tree
population suited to the
urban environment and
adapted to the overall
region. Suitable species
are gauged by exposure
to imminent threats,
considering the "Right
Tree for the Right Place"
concept and invasive
species.
No current
information is
available on species
suitability.
‐ OR ‐
Less than 50% of
trees are
considered suitable
for the site.
50% to 75% of trees
are considered
suitable for the site.
More than 75% of
trees are considered
suitable for the site.
An approved street tree list is available but does not include
consideration for characteristics to help determine appropriate
planting spaces.
Space and Soil Volume
Establish minimum street
tree soil volume
requirements to ensure
there is adequate space
and soil for street trees to
thrive. Minimum soil
volumes by mature size:
1000 cubic feet for large
trees; 600 cubic feet for
medium trees; 300 cubic
feet for small trees.
Minimum street
tree soil volumes
have not been
established.
Minimum street tree
soil volume has been
established based
on mature size of
tree.
Minimum street tree
soil volumes have
been established
and are required to
be adhered to for all
new street tree
planting projects.
No soil volumes have been established; however, tree well size
dictates tree species.
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111 Appendix D: Sustainability Indicators
Table 5: The Players
THE PLAYERS
Indicators of a
Sustainable Urban
Forest
Overall Objective or
Industry Standard
Performance Levels
Low Medium High
Neighborhood Action
Citizens understand,
cooperate, and
participate in urban
forest management at
the neighborhood level.
Urban forestry is a
neighborhood‐scale
issue.
Little or no citizen
involvement or
neighborhood
action.
Some active groups
are engaged in
advancing urban
forestry activity, but
with no unified set
of goals or
priorities.
The majority of all
neighborhoods are
organized,
connected, and
working towards a
unified set of goals
and priorities.
The City has the Downtown Foresters who assist with pruning and
care for small trees in the downtown core.
Large Private &
Institutional Landholder
Involvement
Large, private, and
institutional landholders
embrace citywide goals
and objectives through
targeted resource
management plans.
Large private land
holders are
unaware of issues
and potential
influence in the
urban forest. No
large private land
management plans
are currently in
place.
Education materials
and advice is
available to large
private landholders.
Few large private
landholders or
institutions have
management plans
in place.
Clear and concise
goals are established
for large private land
holders through
direct education and
assistance programs.
Key landholders and
institutions have
management plans in
place.
Green Industry
Involvement
The green industry works
together to advance
citywide urban forest
goals and objectives. The
city and its partners
capitalize on local green
industry expertise and
innovation.
Little or no
involvement from
green industry
leaders to advance
local urban forestry
goals.
Some partnerships
are in place to
advance local urban
forestry goals, but
more often for the
short‐term.
Long‐term
committed
partnerships are
working to advance
local urban forestry
goals.
Some partnerships are in place (e.g., ECOSLO, and Cal Poly).
Page 615 of 748
Appendix D: Sustainability Indicators 112
City Department and
Agency Cooperation
All city departments and
agencies cooperate to
advance citywide urban
forestry goals and
objectives.
Conflicting goals
and/or actions
among city
departments and
agencies.
Informal teams
among departments
and agencies are
communicating and
implementing
common goals on a
project‐specific
basis.
Common goals and
collaboration occur
across all
departments and
agencies. City policy
and actions are
implemented by
formal
interdepartmental
and interagency
working teams on all
city projects.
The different Departments work well together, but the current work
load prevents the optimal level of collaboration.
Funder Engagement
Local funders are
engaged and invested in
urban forestry initiatives.
Funding is adequate to
implement citywide
urban forest
management plan.
Little or no funders
are engaged in
urban forestry
initiatives.
Funders are
engaged in urban
forestry initiatives
at minimal levels for
short‐term projects.
Multiple funders are
fully engaged and
active in urban
forestry initiatives for
short‐term projects
and long‐term goals.
Limited funding comes from local partnerships.
Utility Engagement
All utilities are aware of
and vested in the urban
forest and cooperates to
advance citywide urban
forest goals and
objectives.
Utilities and city
agencies act
independently of
urban forestry
efforts. No
coordination exists.
Utilities and city
agencies have
engaged in
dialogues about
urban forestry
efforts with respect
to capital
improvement and
infrastructure
projects.
Utilities, city
agencies, and other
stakeholders
integrate and
collaborate on all
urban forestry
efforts, including
planning, site work,
and
outreach/education.
Some coordination exists.
State Engagement
State
departments/agencies
are aware of and vested
in the urban forest and
cooperates to advance
citywide urban forest
goals and objectives.
State
departments/agenci
es and City agencies
act independently
of urban forestry
efforts. No
coordination exists.
State department/
agencies and City
agencies have
engaged in
dialogues about
urban forestry
efforts with respect
to capital
improvement and
infrastructure
projects.
State
departments/agencie
s, City agencies, and
other stakeholders
integrate and
collaborate on all
urban forestry
efforts, including
planning, site work,
and
outreach/education.
Page 616 of 748
113 Appendix D: Sustainability Indicators
Public Awareness
The general public
understands the benefits
of trees and advocates
for the role and
importance of the urban
forest.
Trees are generally
seen as a nuisance,
and thus, a drain on
city budgets and
personal paychecks.
Trees are generally
recognized as
important and
beneficial.
Trees are seen as
valuable
infrastructure and
vital to the
community’s well‐
being. The urban
forest is recognized
for the unique
environmental,
economic, and social
services it provides to
the community.
The community is very support of the Major City Goal on Climate
Change/Sustainability and know the importance trees play in this.
Regional Collaboration
Neighboring
communities and
regional groups are
actively cooperating and
interacting to advance
the region's stake in the
City's urban forest.
Little or no
interaction between
neighboring
communities and
regional groups.
Neighboring
communities and
regional groups
share similar goals
and policy vehicles
related to trees and
the urban forest.
Regional urban
forestry planning,
coordination, and
management is
widespread.
Some regional collaboration exists (e.g., participation in regional
pest and disease programs).
Page 617 of 748
Appendix D: Sustainability Indicators 114
Table 6: The Management Approach
THE MANAGEMENT APPROACH
Indicators of a
Sustainable Urban
Forest Overall Objective or
Industry Standard
Performance Levels
Low Medium High
Tree Inventory
Comprehensive, GIS‐
based, current inventory
of all intensively‐
managed public trees to
guide management, with
mechanisms in place to
keep data current and
available for use. Data
allows for analysis of age
distribution, condition,
risk, diversity, and
suitability.
No inventory or
out‐of‐date
inventory of
publicly‐owned
trees.
Partial or sample‐
based inventory of
publicly‐owned
trees, inconsistently
updated.
Complete, GIS‐based
inventory of publicly‐
owned trees,
updated on a regular,
systematic basis.
The inventory is outdated (2008) and not updated regularly when
maintenance occurs. Funds are in place to complete an inventory.
Canopy Assessment
Accurate, high‐
resolution, and recent
assessment of existing
and potential city‐wide
tree canopy cover that is
regularly updated and
available for use across
various departments,
agencies, and/or
disciplines.
No tree canopy
assessment.
Sample‐based
canopy cover
assessment or
dated (over 10
years old) high
resolution canopy
assessment.
High‐resolution tree
canopy assessment
using aerial
photographs or
satellite imagery.
Aerial imagery was analyzed to understand canopy cover in the
urban areas (2012).
Management Plan
Existence and buy‐in of a
comprehensive urban
forest management plan
to achieve city‐wide
goals. Re‐evaluation is
conducted every 5 to 10
years.
No urban forest
management plan
exists.
A plan for the
publicly‐owned
forest resource
exists but is limited
in scope,
acceptance, and
implementation.
A comprehensive
plan for the publicly
owned forest
resource exists and is
accepted and
implemented.
There is not an urban forest master plan, but funds are in place to
compete a plan.
Risk Management
Program
All publicly‐owned trees
are managed for
maximum public safety
by way of maintaining a
city‐wide inventory,
conducting proactive
annual inspections, and
eliminating hazards
within a set timeframe
based on risk level. Risk
management program is
Request‐based,
reactive system.
The condition of
publicly‐owned
trees is unknown.
There is some
degree of risk
abatement thanks
to knowledge of
condition of
publicly‐owned
trees, though
generally still
managed as a
request‐based
reactive system.
There is a complete
tree inventory with
risk assessment data
and a risk abatement
program in effect.
Hazards are
eliminated within a
set time period
depending on the
level of risk.
Page 618 of 748
115 Appendix D: Sustainability Indicators
outlined in the
management plan. There is not a risk assessment program.
Maintenance Program
of Publicly‐Owned Trees
(trees managed
intensively)
All intensively‐managed,
publicly‐owned trees are
well maintained for
optimal health and
condition in order to
extend longevity and
maximize benefits. A
reasonable cyclical
pruning program is in
place, generally targeting
5 to 7‐year cycles. The
maintenance program is
outlined in the
management plan.
Request‐based,
reactive system. No
systematic pruning
program is in place
for publicly‐owned
trees.
All publicly‐owned
trees are
systematically
maintained, but
pruning cycle is
inadequate.
All publicly‐owned
trees are proactively
and systematically
maintained and
adequately pruned
on a cyclical basis.
Trees in the Downtown core are well maintained, all other
maintenance is reactionary.
Maintenance Program
of Publicly‐Owned
Natural Areas
(trees managed
extensively)
The ecological structure
and function of all
publicly‐owned natural
areas are protected and
enhanced while
accommodating public
use where appropriate.
No natural areas
management plans
are in effect.
Only reactive
management
efforts to facilitate
public use (risk
abatement).
Management plans
are in place for each
publicly‐owned
natural area focused
on managing
ecological structure
and function and
facilitating public
use.
n/a
Planting Program
Comprehensive and
effective tree planting
and establishment
program is driven by
canopy cover goals,
equity considerations,
and other priorities
according to the plan.
Tree planting and
establishment is outlined
in the management plan.
Tree establishment
is ad hoc.
Tree establishment
is consistently
funded and occurs
on an annual basis.
Tree establishment is
directed by needs
derived from a tree
inventory and other
community plans and
is sufficient in
meeting canopy
cover objectives.
Although Urban Forest Services does not have a planting program,
staff partner with ECOSLO for tree planting.
Page 619 of 748
Appendix D: Sustainability Indicators 116
Tree Protection Policy
Comprehensive and
regularly updated tree
protection ordinance
with enforcement ability
is based on community
goals. The benefits
derived from trees on
public and private
property are ensured by
the enforcement of
existing policies.
No tree protection
policy.
Policies are in place
to protect trees, but
the policies are not
well‐enforced or
ineffective.
Protections policies
ensure the safety of
trees on public and
private land. The
policies are enforced
and supported by
significant deterrents
and shared
ownership of city
goals.
Municipal Code Chapter 12.24 provides protections for the majority
of trees (public and private).
City Staffing and
Equipment
Adequate staff and
access to the equipment
and vehicles to
implement the
management plan. A
high‐level urban forester
or planning professional,
strong operations staff,
and solid certified
arborist technicians.
Insufficient staffing
levels, insufficiently‐
trained staff, and/or
inadequate
equipment and
vehicle availability.
Certified arborists
and professional
urban foresters on
staff have some
professional
development but
are lacking
adequate staff
levels or adequate
equipment.
Multi‐disciplinary
team within the
urban forestry unit,
including an urban
forestry professional,
operations manager,
and arborist
technicians. Vehicles
and equipment are
sufficient to
complete required
work.
Equipment for the program is adequate. The staffing level is low due
to the current transition period.
Funding
Appropriate funding in
place to fully implement
both proactive and
reactive needs based on
a comprehensive urban
forest management plan.
Funding comes
from the public
sector only and
covers only reactive
work.
Funding levels
(public and private)
generally cover
mostly reactive
work. Low levels of
risk management
and planting in
place.
Dynamic, active
funding from
engaged private
partners and
adequate public
funding are used to
proactively manage
and expand the
urban forest.
Funding is currently allowing Urban Forest Services to complete
reactive maintenance and begin transitioning to cycle pruning.
Disaster Preparedness &
Response
A disaster management
plan is in place related to
the City's urban forest.
The plan includes staff
roles, contracts,
response priorities,
debris management and
a crisis communication
plan. Staff are regularly
trained and/or updated.
No disaster
response plan is in
place.
A disaster plan is in
place, but pieces
are missing and/or
staff are not
regularly trained or
updated.
A robust disaster
management plan is
in place, regularly
updated and staff is
fully trained on roles
and processes.
Urban Forest Services plays a significant role in the City‐wide storm
response plan.
Page 620 of 748
117 Appendix D: Sustainability Indicators
Communication
Effective avenues of two‐
way communication
exist between the City
departments and
between city and its
citizens. Messaging is
consistent and
coordinated, when
feasible.
No avenues are in
place. City
departments and
public determine on
an ad‐hoc basis the
best messages and
avenues to
communicate.
Avenues are in
place but used
sporadically and
without
coordination or only
on a one‐way basis.
Avenues are in place
for two‐way
communication, are
well‐used with
targeted,
coordinated
messages.
Avenues for communication are in place, but workloads interfere
with a high level of messaging.
Page 621 of 748
Appendix E: Community Survey 118
Appendix E: Community Survey
1. Trees are important in San Luis Obispo for the following reasons (choose your top 5).
Response
%
Number of
Responses
Shading/cooling 61.8% 398
Community character/aesthetics 58.5% 377
Wildlife habitat 54.8% 353
Improving air quality 53.9% 347
Connection with nature 46.6% 300
Quality of life 46.4% 299
Reducing urban heat island effects 42.6% 274
Greenhouse gas reduction 35.3% 227
Reducing energy needs 16.8% 108
Reducing stormwater runoff 15.7% 101
Reducing stress 14.4% 93
Enhancing pedestrian/bike corridors 13.4% 86
Screening/creating privacy 8.5% 55
Increasing property values 6.4% 41
Reducing health incidence/cost 4.5% 29
Increasing retail sales 1.7% 11
Safety/reducing crime 1.4% 9
Other (please specify) 2.2% 14
All of the above; I should not have to choose just 5.
Carbon sequestration
Providing beautiful shade
this entire list are my reasons
promoting sustainability and nature
We need to improve the how do I say this the overall canopy. We need
more instead of cutting down native trees for housing. They need to be
replaced with natives not ornamental
Climate Control
Urban Wildfire Interface Defensive Planning‐Veg Mgmt
Really, aren't all of the above important? I think so.
Natural Beauty
The trees are terrible for the city. The sidewalks are popping up very dirty
and it changes the attitude of people in the city to not take care of our city
it is filthy along with the shoe polish
Traffic Calming
Life all life! Trees aren’t important they are essential? Who’s writing these
questions???
Total
644
(0 skipped)
Page 622 of 748
119 Appendix E: Community Survey
2. What do you feel is the most important environmental benefit from trees (choose one)?
Response
%
Number of
Responses
Greenhouse gas reduction 22.1% 142
Shading/cooling 21.3% 137
Reducing urban heat island effects 20.2% 130
Improving air quality 18.3% 118
Wildlife habitat 13.4% 86
Reducing stormwater runoff 2.8% 18
Other (please specify) 2.0% 13
All of the above; I should not have to choose just one.
All of the above
All of the above. You're not giving us the opportunity to tell you what
trees REALLY mean while you're chopping down hundreds all over the city.
my feelings are irrelevant, no need to choose when they do all, this is a
silly question
Oxygen production
Trees absorb carbon and give off oxygen. We need all the ways of
absorbing carbon we can find to combat climate change/global warming.
Trees are just plain good.
the calming, beneficial, aesthetics valley of living beings that offer nothing
but wholesome good feelings and a critical vital connection with our
creator that instills comfort, warmth and security.
Don't make me chooooooose!
Reducing urban heat AND shading, cooling
Everything. Trees are essential for all of the above reasons!! Essential for
all life!
Overall benefits of nature ‐ all of the above
Total 644 (0 skipped)
3. What do you feel is the most important socioeconomic benefit from trees (choose one)?
Response
%
Number of
Responses
Community character/aesthetics 32.8% 211
Quality of life 24.2% 156
Connection to nature 16.6% 107
Reducing energy needs 11.5% 74
Enhancing pedestrian/bike corridors 3.6% 23
Reducing stress 3.1% 20
Increasing property values 2.3% 15
Reducing health incidence/cost 2.0% 13
Screening/creating privacy 1.1% 7
Increasing retail sales 0.6% 4
Safety/reducing crime 0.5% 3
Page 623 of 748
Appendix E: Community Survey 120
Other (please specify) 1.7% 11
All of the above. STOP THE MASS tree cuttings!!
again, really? its a fact, has socioeconomic benefits, no need to choose
You can't separate the affects of trees socioeconomically because it's all
connected to human/nature . One affects the other spiritually, psychically
socioeconomically
Shading/cooling
Shade and protection from rain for our homeless neighbors
all of the above
Berries all over the cement
There could be more than one socioeconomic benefit.
wildlife habitat‐including bees and other pollinator insects/birds
Life!!!! All life dies without trees. Is this a real survey?
Total 644 (0 skipped)
4. Where do you think it is most important to plant more trees (choose up to 3)?
Response
%
Number of
Responses
Neighborhood streets 77.3% 486
Parks 54.5% 343
Open space 40.9% 257
Medians 34.7% 218
Retail areas 29.3% 184
Arterial roads 28.9% 182
Other (please specify) 7.6% 48
Along bike/walking paths
everywhere
udeveloped lots
Maintain mature trees on new construction
Everywhere ‐ you've cut down so many we won't be able to replace them
for decades.
everywhere we can!
everywhere
If you replace trees in one area you need to replant in that area. Also
instead of cutting down trees when building find a way to build around the
trees. Make them or it a part of the landscape of the new building
projects
New neighborhoods
Schools
SCHOOLS
Schools
Schools
In new housing or commercial developments
All of the above
Page 624 of 748
121 Appendix E: Community Survey
Schools
Razed developments
Waterways
Downtown
Stop removing so many tree @ new developments
Anywhere there isn't much nature, aka wherever there's concrete.
Trees provide cooling in overly concreted areas, and in every area if they
are allowed to grow large enough.
Parking lots
Parking lots
ALL the above
Replacement of trees removed for disease or public safety wherever they
may be.
Everywhere we can
Between freeways & neighborhoods
All of the above reasons
Schools! There is hardly any shade at the schools
Parking lots
Everywhere possible.
AWAY FROM HIGH VOLTAGE ELECTRIC DISTRIBUTION LINES
All of the above
Anywhere they’re less likely to be involved in wildfires?
Pedestrian and bike lanes
Parking lots that are giant asphalt islands
all new construction...speaking of where is all the water going to come for
all the new construction? And where is the affordable housing?
Private property where trees can be maintained year round.
Everywhere there is room to plant!
Only plant trees of you can take care of them and water them
Arterial roads should be downgraded and made pedestrian‐friendly with
trees planted
in traffic circles/bulb‐outs/medians/etc. Trees/plantings should be used as
traffic calming devices.
Please plant trees in medians where you can also provide pedestrian‐
friendly infrastructure (stop signals, crossings, flashing lights). Trees in a
well‐designed median don't do much to encourage walking for streets that
are a hundred feet wide.
All of the above
Silly question
All of the above
Open spaces should be left as natural as possible, if no trees in them
naturally, don’t add them
Total 629 (15 skipped)
Page 625 of 748
Appendix E: Community Survey 122
5. What are the best ways to encourage tree planting on private property (choose up to
3)?
Response
%
Number of
Responses
Free or low‐cost tree 72.0% 453
Rebate on water bill 61.2% 385
Rebate on purchased tree 49.4% 311
Tree species and site selection information 45.0% 283
Community tree planting event 34.7% 218
Other (please specify) 7.0% 44
City support on recommended trees and locations
Let's protect the mature trees we have and not allow their removal.
PLEASE!
Low cost native and/or drought‐tolerant trees, rebates on property tax
All of the above
Discourage developers removing mature trees, financial incentives to plan
and build around existing trees
Allowing only minimal cutting of trees for a development project will
encourage others to plant trees knowing they won't be removed
Low cost maintenance agreement
Free food
Lawn sign or decal "Proud Participant in the SLO 10,000"
Native plants/drought resistant
Rebate/Free tree trimming
Requirement Assoc w new construction, remodel, etc
Tree pruning and fire defensive planning is essential
education and replanting requirement
$ incentive for individuals or small businesses, city money shouldn't pay
for corps to green wash.
Tax rebate
Tax incentive
To have a awesome City tree crew and program
Clear planting and maintenance guidance
The city could water the trees for 2 years w/recycled water as done at
Laguna Lake Park.
Having the City plant the trees, with permission of property owners, and
perhaps with offering a few different tree choices
Free or low cost native tree
Follow up after the tree planting (All of the above!).
offer assistance with tree maintenance & care
All of the above
on going tree maintenance after new planting
Tools to succeed: example Irrigation kit?
Education on which species support NATIVE wildlife AND a financial
incentive for native species
Page 626 of 748
123 Appendix E: Community Survey
Education about importance of trees for birds and wildlife
Include edible trees in selection (citrus, feijoa, loquat, mulberry, etc...).
Homeowners value fruit producing trees.
Free pruning
Massive volunteer effort to plant trees. Use CP and Cuesta volunteers.
Photo contest
Free or low cost trimming & raking when necessary
education on why we want people to plant trees
Don’t allow developers to remove mature trees for subdivisions
Na
Tree species and site selection ASSISTANCE (consultation, not just
information)
I don't know how much encouragement people need, people enjoy having
trees and seem to do a good job of planting them on their property if it is
appropriate.
Provide planting service
Not sure we s/b encouraging potential fire hazard
I would say rebate on water bill‐but that should only apply for native
plantings that won't increase water usage over the long run
Start by talking to people, information is key. Stop putting out surveys
that give people the opportunity to rate essential things as though they
weren’t.
Consider free or low cost fruit trees for private property
Total 629 (15 skipped)
6. Describe your awareness and/or interactions with San Luis Obispo’s urban forest
program (check all that apply).
Response
%
Number of
Responses
I have seen City crews working on trees 70.3% 423
I was aware that the City responds to tree emergencies 52.8% 318
I did not know the City had a program to care for trees 25.4% 153
I have used the City website or called for tree information 20.4% 123
I have read an article in The New Times or The San Luis Obispo Tribune
about trees 15.6% 94
Other (please specify) 9.0% 54
I have volunteered at tree related events 8.3% 50
the importance of city arborists
I have called the Davey group in response to a flier they left offering tree
service on our powerlines and they did not return a call nor show up until a
year later
I learned about it through my GIS class!
Taken classes in dendrology and surveying and became familiar with
forestry and management practices in the area
Page 627 of 748
Appendix E: Community Survey 124
I have taken a Urban Forestry class at Cal Poly
I took Urban Forestry at Cal Poly
I know people on the Tree Committee.
Need to maintain all mature trees in new construction!!!!
Too many trees removed for development
I have been involved as a citizen in promoting the urban forest program
I have seen many trees removed for urban development when they could
have been incorporated into the plan.
Attended the arbor day event with my sons school
Certified arborist who has tree issues with neighbors
I have seen the city approve cutting down massive numbers of our urban
forest trees
I received a city notice of meetings. I have been talking to people about
trees in area I live that new building cutting down trees. I've been
concerned and didn't know who to talk to. There's a big oak and granite
right next to where I live and building is planned. I do not want to see this
removed. I've been in cities that literally include trees and granite stone
within the buildings they've built. We have made it too easy just to
bulldoze things down because it's easy way out. We need to understand
the connection to nature. Our survival depends on it.
the city keeps cutting down trees
Many mature, local trees have been cut down for development.
I heard about the program through EcoSLO
We have a huge oak on property and use tree care professionals once a
year
My Dad use to be the manager for parks, buildings, and street trees for SLO.
Have planted trees at arbor day event at Mitchell park
Attempted to increase more wildland fire interface veg mgmt awareness at
city boundaries and roadway shoulders
I was told the city waters street trees, but I rarely see it happen‐‐should
happen more often.
A BUDDY WORKS THERE
I was liaison to Tree Committee during terms on City Council
I have looked into preventing sycamore planting bc I'm allergic to them.
I have attended a tree committee meeting.
The city has trimmed trees in our neighborhood parkways.
why does the Tree Committee allow removal of the vast majority of trees
that come before them? Why does the city of slo allow developers to
remove so many beautiful mature trees & then plant small ones. The GHG
& Climate Change seriously necessitates protecting our mature trees for
many science based reasons. The city is a huge tree killing machine!
Went befor the tree committee.
I have been to a tree committee meeting and know how strict & difficult
the City is with removing and planting trees
I knew there were people that maintained them, but didn't know about the
urban forest program per se.
Page 628 of 748
125 Appendix E: Community Survey
My children's school participated in an Arbour day art contest and tree
planting event
They planted trees in neighborhood. I wish every street was like Mill street,
beautiful tree lined streets
I don't think there's much awareness of the program
I am an arborist and nearly applied to apply for an open position in the
urban forestry group in the past.
Trying to remove a tree causing major property destruction at my office.
The city arborist called me
I saw former mayor Heidi Harmon post about it
Served as liaison to Tree Committee from City Council.
Though a Cal Poly urban forestry class
Unfortunately, there are a lOT of trees not maintained...all along Johnson
by French Hosp, Bowden Ranch open area. Dead trees down...fire concern.
Member of Tree Committee for 8 years
I had to work with Ron on a building permit tree requirement.
Na
I have attended Tree Committee meetings
organized a tree planting event, been to street tree comm. meetings, had to
get permission to remove trees, my tenant dated the last street tree
guy.......
The city cannot take care of of what they have now
I have used the Cal Poly tree/attribute list for evaluation of street tree
options
Trees planted with memory plaques
I have a colleague who serves on the City's Tree Committee and has
informed me how tight of a budget the City has to care for all of its
beautiful trees. We need to incentivize private investment in trees (by
individual homeowners and businesses) to help offload some of the future
maintenance obligations.
None. This survey has been enlightening
I am aware they exist but have seen no activity
I am aware that there is a program but have not seen it working.
Total 602 (42 skipped)
7. What is your satisfaction with the level of care provided for community trees?
Response
%
Number of
Responses
Somewhat satisfied 38.4% 231
Neutral 32.1% 193
Completely satisfied 12.8% 77
Somewhat dissatisfied 11.1% 67
Completely dissatisfied 5.7% 34
Total 602 (42 skipped)
Page 629 of 748
Appendix E: Community Survey 126
8. Do you feel that urban forest services and programs are equally accessible to all
residents?
Response
%
Number of
Responses
Not sure 63.3% 381
No 20.3% 122
Yes 16.5% 99
Total 602 (42 skipped)
9. What topics of education and outreach interest you (check all that apply)?
Response
%
Number of
Responses
Tree list/what tree should I plant in San Luis Obispo 84.6% 509
Irrigation/watering during drought 73.9% 445
How to plant a tree 47.7% 287
Benefits of trees 46.5% 280
How to hire a tree care professional 28.4% 171
Other (please specify) 6.5% 39
Come look at my HOA and help us decide about our trees.
SLO City staff needs to be educated about benefits of keeping the trees we
already have and not replacing them with trees that will take decades to
reach the size and advantages of the ones they killed.
More discussion of tree removals for development
Stop cutting down mature trees on all new construction!!
How to stop or minimize tree destruction currently happening during
urban development.
Identify problem trees and remedy
How to care for and prune a tree
People understand trees. Find ways to reduce water cost because the city
has increased water rates after encouraging saving water.
how to avoid cutting trees down
Where to plant trees, how much space is needed
stop cutting down trees. developments can build around them
Benefits of planting more fruit trees.
By
All of the above
On‐site school education
Home tree/City boundary/Roadway area defensive veg mgmt for wildfire
protection of neighborhoods
provide tree information (like root damage to roads/sidewalks) for various
trees that can be planted.
Clarity on rules for neighborhood roadside trees, creek side trees support
for replacing trees with native trees
Page 630 of 748
127 Appendix E: Community Survey
How to accelerate tree planting throughout the County to achieve ghg
reduction
Tree list should specify soils requirements for particular trees, natives
should be encouraged.
It seems like native trees like the Coast Live Oak can survive better during
droughts & climate change. Our tree committee is pathetic. They're
aligned with developers & tree killers.
none interest me
emphasize California native trees ‐ educate public Doug Tallamy videos
None; I rent and can't afford the time nor a place
Support for trees on residential properties
I wish the city would help take care of the planter boxes that are in the city
right away, I live on Lawton street and most of the curb planter boxes are
weeds and it looks terrible. I wish there was some incentive for the home
owner or the city to take care of this space and would be nice if it had a
uniform look.
All of the above.
How the city incorporates awareness of facilities that can be negatively
impacted by trees.
Tell me about all these health benifits.
Educate developers to plan development around existing trees.
NA
I know what I am doing
Na
support people who have a tree issue and not charge them if desiding the
free shoud be removed
impact when mature trees are cut for developers
We’re American we don’t need anymore stinking tree in fact if we kill
them all we’ll have more room for people and stuff. Too if we get rid of
all the trees we’ll likely wipe out our homeless problem. They already
have no indoor respite so making the outside even more unbearable will
aid the City in their current efforts of “anywhere but here.”
None
None
Clarity about tree removal and re‐plantings
Total 602 (42 skipped)
10. Optional. Please use this space for any additional comments about San Luis Obispo's
urban forestry program.
If the City values trees so much, why are so many trees being allowed to cut down in the project off of
Highland Dr.?
More trees please
I support urban forestry. Too many trees are cut down for and by developers. Some of your questions
were loaded and the forced choices were sometimes insufficient.
https://www.facebook.com/TreesDoc
Page 631 of 748
Appendix E: Community Survey 128
We must make protecting our mature trees a priority. It is no longer prudent to cut down mature trees
and replace them with trees that won't serve us well for 20 years into the future.
Let’s be very careful about eliminating existing healthy trees for the sake of new developments. Very
important that any replacement trees be of significant size and quantity (more than equal to those
removed!) to enhance the project.
I think it is time to find a species of tree to start replacing the ficus trees downtown that are tearing up
sidewalks.
prevent developer removing quality mature trees
Maintain a level of staffing and funding to meet Arbor Day Foundation recommendations.
The program should also work to remove invasive species when possible from public places and encourage
private citizens to replace them with native species.
Get rid of the cattle fields in the city limits and replant that land with native trees. I’m thinking of the
field/hill along broad, between orcutt rd and tank farm.
community outreach is very important and i love the possibilities of there being some incentive and
community aspect in planting trees
More accessibility for the public to plant trees/care for them and know what kinds of trees encourage our
local habitat.. Maybe monthly community tree planting with different chapters around SLO county.
why isn't the city watering the trees in our parks, they are dying!
Please plant more female trees on city streets, excessive male trees are serious allergy issues.
I am concerned that too many mature trees are being removed and their surrounding ecosystems are
damaged for new construction projects.
Stop approving new housing and retail development that requires taking down significant numbers of
trees. Encourage creative designs so that existing trees can be maintained for environmental and visual
esthetics.
There are posts in social media that the City is removing over 1000 mature trees to accommodate
development. I don't know if it is true or not, but perhaps more information could be provided to the
public about tree removal programs.
Work w the city to leave more ‘set back’ space between streets and homes, offices, etc. Demand architects
& builders don’t skimp on green areas, that is, less concrete & MORE trees & plants as a buffer.
Trees in the down town go through a messy stage & the merchants/city does not clean up the pods/leaves
that drop. Garden street is the cleanest due to merchants/owners cleaning the sidewalks.
I walk to work and there are a lot of messy trees. It would be beneficial to focus on planting trees that are
not so messy along sidewalks. Also adding additional trees along residential quarters. The shadiest street is
Pacific on my route but I typically walk on Islay and Buchon.
Really sad that the city is allowing developers to completely eradicate mature trees and not making them
replace with older trees, just making them plant super young trees that have no benefit to wildlife or air
quality or reduce greenhouse emissions for years. No removal of older trees should be allowed unless they
are diseased.
The city shows its bias for developers and the funds new development provides by allowing hundreds of
mature and healthy trees to be removed in recent years. SLO City staff is saying one thing and showing
complete disregard for the trees already in the city if they're in the way of development.
The city requires a property owner to get permission to remove a tree, requires replacement planting, but
never checks to see that the replacement planting has taken place.
The city in some parts of town have used tree trimmers for city trees that appear to lack basic knowledge
about how to prune large trees ‐ for instance the block of Chorro between Marsh and Higuera ‐ second for
instance the liquid amber street trees in my neighborhood that were trimmed in a way that opened them
up, left long branches with growth only near the ends that then let the branches "bounce" much too much
on windy days and encouraged broken branches.
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And to partially repeat ‐ it is "criminal" that so many mature trees have been sacrificed in recent years
(Righetti Ranch, Avila Ranch, San Luis Ranch, etc.) to satisfy the greed of housing tract developers who
aren't even local.
Please preserve existing mature trees whenever and wherever possible, especially in new developments.
I am very concerned about the destruction of trees along city’s riparian corridors. Proper planning and
design could have saved these trees. New residential development even to meet state mandates for local
financial support, should take a back seat to saving these trees. The urban forestry program is will be
unable to offset the loss of mature trees by supplanting with immature trees for years to come.
The city allowed the cutting of many full grown trees for housing developments. The new developments
could alter their plans to save more full size trees. I’m aware the city will require planting of trees. The
new trees will take years to be full grown. The city doesn’t walk the talk with trees.
The trees on downtown Higuera are beautiful. We need more streets like it.
Please don't remove any more trees in the city in the name of development. Design any future
developments around any mature trees, our environment is counting on the city to do the right thing.
Why isn’t the Slo urban forestry more involved with planning and development expansion into formerly
open spaces (either private or public) where tree removals are proposed. Shameful planning process when
the removal of mature trees is/are a part of. ….
All approved removal of trees on new construction should be stopped immediately!!!!
While there may be an urban forestry program, I cringe every time I pass a new development where
existing mature trees/habitat have been destroyed to allow for maximum density of units abetted by the
unchallenged cooperation of city government. Progressive cities like ours should lead the way in tempering
our desire to provide additional housing with the restraint necessary to keep from destroying the very
reason we love our community.
SLO is allowing too many mature tree removals and tiny trees planted in their place which does not
sequester carbon amounts the mature trees did. This will work against Climate Change efforts that are so
important. Too many trees are killed for development with the City’s permission.
PLEAE STOP THE MASS TREE REMOVALS. YOU HAVE ALREADY DESTROYED HABITAT AND ARE CAUSING US
TO PUT THOUSANDS OF POUNDS OF CARBON IN THE AIR DAILY. SHAME ON YOU!!!
love that street trees have been planted by cutting holes in concrete on sidewalks. plant more trees in
medians and roundabouts, add speed humps to streets to slow down vehicles.
stop approving developments which cut down mature trees and replace with small trees
Developers should be required to save old growth trees and also plant more trees as part of the
development.
Stop allowing tree removal.
I live 2 blocks from CalPoly and there is constant building in the area. I am aware of the preferences for
infill building and ADUs, but I constantly see that trees and yards are allowed to be removed and built
upon. This is an older neighborhood that contains many mature trees and gardens, many created by
professors of the past as a lasting legacy for the community. This legacy is fast disappearing, along with
the environmental and aesthetic benefits of trees and plants. Housing is important and I am aware of the
mandate to build, build, build; however the quality of our neighborhoods should be respected. If student
rentals are purely cement and stucco, what are we demonstrating to the leaders of tomorrow?
And basically, if there are no trees to breathe, then we cannot breathe either!
Also, Davey Tree is not one of my favorite arborists. I seldom see a tree cut by them that doesn't look
hacked and miserable.
Mature trees in the city need to be protected and preserved. Removing mature trees for development and
replacing with immature saplings needs to be avoided and incentives should be provided to developers to
preserve the existing urban forest.
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Return the Tree Ordinance to the strong ordinance it USED to be before Matt Horn destroyed the Tree
Ordinance. If you want to improve the quality of life for SLO residents, fire Matt Horn.
I love the city’s commitment to this important quality of life issue. Thank you!
We need more trees!! We love watching the animals use the trees! We moved here from Davis where the
tree canopy was extensive and we really enjoyed it!!
Not sure if it’s relevant but trees and sidewalks should be friends. There are places it can be difficult to
walk due to trees needing a prune such as along Sacramento street and along neighborhood sidewalks.
I have been surprised by permits allowing the complete clearing of mature trees on residential lots without
a requirement to replant equivalent numbers after building.
The trees chosen in the past have been terrible. Ficus nitida is the worst street tree you could find.
Camphor is beautiful but not appropriate for street trees. New buildings are being built that have no
setback from the street for trees. ???
Please don’t reduce the tree program! We need more trees!
Overall happy, but sad to see the large redwood at Amholm Park have its roots cut. I'm guessing it's a trip
hazard but cutting surface roots on a redwood is very damaging and it hasn't fixed the trip hazard. I would
be very upset if the tree died as a result of poor management. Please look into the care of that beautiful
redwood and help it out.
Due to proximity of monarch butterfly migration sites, we should include more nectar flower trees to give
them energy to make it to the overwintering sites.
We are blessed to live in an area that can support food bearing trees. We should plant several throughout
the city for citizen use. Including things like citrus, avocado, persimmon, etc.
more trees needed in neighborhoods with large streets/arteries like Ramona Drive. SLO Drive
neighborhood is so desirable because its got lots of big trees, which are charming and healthy and
represent quality of life.
With water costs, how does the community get trees established with proper irrigation.
Tree form selection, upright canopy vs. multi low branching is critical to long term success.
the city used to water trees and now it doesn't anymore, why?
Loss of new trees is discouraging (e.g., to gophers, poor watering during establishment), so ramping up
with successful early plantings seems important
It has been shocking to see so many trees needlessly cut down. Developers can work around nature and
not have to clear‐cut.
I'm not informed enough on what is presently being done. I only know we do need to improve our canopy.
I don't want to see city use pesticides/herbicides and I'd like to see public better educated on their use and
negative affects on human Flora and fauna.
there is no urban forestry program. when a developer wants to clearcut trees the city allows it. the city
also does not follow its own rules about requiring additional trees to be planted with new development
There is a low hanging branch of a tree on the sidewalk of Stenner street that could be a potential hazard.
Please preserve mature trees and speak up about their preservation during the development process.
In older neighborhoods, city trees were planted that have caused damage to sidewalks, driveways,
foundations as well as excessive leave/ needle litter that clog storm drains.
I think there should be an effort to plant more fruit trees in public spaces. As long as we're making an
effort to increase urban forests, why not plant something that we can eat? Free fruit to anyone willing to
harvest it. What a concept!
I don't think that many people, especially students in SLO, know about the urban forestry program and
how they could interact with and utilize this program. I might be unaware if there is any, but I think this
program should find more ways to connect with Cal Poly.
Please consider planting native tree species for new plantings. They will thrive in our climate and support
wildlife
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Many trees should be planted in new neighborhoods like San Luis ranch
Very disappointed that folks remove trees from parkways and do not replace. It seems if trees are
mandated for parkways, then there should be some enforcement of this mandate.
Is there a volunteer program with the urban forestry in slo?
I think another incentive would be for the city to cover cost of ripping out concrete in sidewalks for tree
placement. I would really like to see the city encourage planting of natives as much as possible. These have
a much greater benefit for wildlife and are best adapted to our environment. Perhaps incentives could be
larger for native plantings.
In Cambria we have several well educated and capable tree specialists who assist in permitting, removal,
maintenance etc. our trees. Thank you for this opportunity to chime in.
Thanks for caring for the trees. Does the city provide water for trees in open spaces, such as the many oak
trees? I heard many are dying due to drought conditions.
I want to see protection for all oaks and mature trees when new subdivision permits are granted. Case in
point: the removal of oaks by wealthy winery owner in 2015 in North SLO county.
Thank you for reaching out to the community. Please look at our public school's needs for trees. Many of
the school sites in SLO can benefit from more trees.
I would love more trees! There are a lot of places where tall weeds grow on the sidewalk
that the city should be maintaining— just want to make sure we take care of what we have too :)
There is a huge lack of trees at schools. Blacktops are SO hot and there is no shade for students. ECo Slo
had FREE trees for Pacheco this year and they would not take them. We tried to facilitate planting but the
school would not allow them. Too much work or concern with kids climbing? City should impose same
requirements on schools as homes. They must have trees. Look at an aerial of any neighborhood and it’s
the most grass, least tree area. Crazy. I think you could add hundreds of trees to our school and make a big
impact.
The more outreach the city does regarding their tree policies and general tree care BMPs (both for
community as well as private trees), the more the residents will benefit.
Glad this is a topic of conversation. Trees are so necessary! Please add more to the schools. After so much
construction at each site, the trees were the first to be moved to give room for the new facilities.
I would like to see wood from trees cut down to be repurposed for furniture, instruments, or art
Street trees need to be planted in established residential areas where trees are lacking. The lack of trees in
the historic and downtown areas are a good example.
The more trees the better
I think we really need to focus on planting more trees in our city especially at our schools. Our youth need
to see the process of planting a tree and the care if provides from a educational stand. We also
DESPERATELY need more shade at our elementary schools
First off stop cutting down the “urban forest” because a developer can’t figure out how to design a project
around mature trees regardless of the are “native” or not. Maybe the City needs to read the it’s Land Use
Element a little more carefully. It’s says new development is supposed to respect existing trees on the
project site. I don’t think cutting them down is what is meant by respect.
Proper pruning is crucial for shaping the canopy. So many trees in town have been butchered (esp the
sycamores). Please have educational opportunities for local landscapers to learn how to care for local
trees.
The Urban Forestry Program needs to be part of a City standing taskforce/working group with Fire
Department/Parks Dept/Public Works to conduct wildland fire interface vegetation management projects
along open space boundaries, roadway right of ways and city boundaries with areas such as Cuesta Park to
reduce ladder fuels and maintain defensible space in the event of wildfire
The street tree in front of our house is barely surviving. The city is supposed to water and take care of it,
but I doubt they are doing anything. How do I contact the SLO urban forestry program people?
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Who is responsible for sidewalk repair when city tree roots raise/break sides?
I’d like to see easier outreach and info for caring for trees, and the rules surrounding trees esp “sidewalk”
trees and support for re planting w drought tolerant natives
Regarding trees only in the downtown core: they are very poorly managed and trimmed. The primary goal
of these trees is to provide shade, not just to look pretty. The more shade, the longer people will linger
downtown, providing an economic benefit to businesses. Trees are trimmed far too high above sidewalks
and the street; doing that reduces shade in mornings and late afternoons. When trees are removed they
should be replaced with larger trees than saplings. There are two types of trees downtown. One type
provides nice shade, the other does not. Those scraggly trees should be replaced by the better shade
species. There are far too many gaps between trees on many streets. Plant more trees! Line the streets.
Our trees are what makes downtown SLO unique, for the shade the trees provide.
I am extremely grateful for SLO's urban forest.
It is why I shop here rather than in surrounding communities‐‐
all the shady parking.
And I brag on that very benefit every chance I get.
I have lived in over a dozen communities in 8 states, and SLO has by far the most satisfying, soothing,
calming presence of all.
In my opinion, you can never have too many trees!!!
Thank you, SLO urban foresters!!!
Give a higher priority to keeping existing trees when permitting new development.
Please stop allowing development plans to cut so many trees. Make plans fit into the site, not try to
remake the site.
The City should consider (and promote if it exists) a program/fund/bank that allows private property
owners to pay into when on‐site replacement to offset tree removal isn’t feasible or appropriate due to
soil type, topography, or other property constraints. Not all lots in SLO should have trees. I haven’t
removed a tree that requires a tree removal permit that was planted too close to my house which is in a
fire hazard zone because my lot doesn’t have any suitable spots for the replacement requirements. I’d be
very happy to pay a fee that supports the replacement at 1:2 or more in a more appropriate location
somewhere else in SLO. This plan should identify the preferred and most suitable locations that maximize
benefits to the environment and community.
Species list for street trees should be revisited. Add more options, but be aware of pollen allergy ratings!
(looking at you sycamore, I can't go outside in my neighborhood during windy days in spring since
sycamore were added a few years ago). Native trees are best. Drought tolerant are a must. Trees with
flowers are nice, ie crepe myrtle, jacaranda, the ones w yellow flowers in the creamery. (Not mimosa trees,
I'm also allergic. It's a sad life.)
I'm not a big fan of the particular street trees downtown. I like trees, just not that overwhelming? It was a
great idea to plants them in the 50s (sad we can't see the mountains, but benefits make it worth), however
now they are huge! Destroying sidewalks and dominating historic facades. Also, if your dog eats enough of
those seed pods they get diarrhea. :(
Planting trees in open spaces is great! If budget were unlimited I'd say definitely do that. Since that's not
reality, my focus would be on areas human's hindered nature (with structures and paving). More trees in
parks is also a plus, but I feel like y'all are already pretty good at that.
I love trees and I'm excited to see where the City goes from here! Thank you for the survey!
Please stop removing large trees from the downtown areas. We've lost so much shade, cooling benefit
and character in these losses. It seems tree removal is very easy for anyone who seeks it. Replacing trees
with a much smaller tree will take decades to provide the same benefits. Look at the character of a place
like Carmel, CA where large trees grow in the middle of neighborhood streets. Traffic is calmed
dramatically, shade is abundant and cooling is easy to find. We keep removing our assets!
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I would be happy to be involved as a taxpayer
Because it is hard to get a tree removed (permits and cost) it would be nice to mail new homeowners a
tree planting guide. Most nee homeowners will plant a tree‐ but they don’t know what they’re doing.
I worry about tree removal for developments, especially older trees that are well established. Too many
older trees are removed and ‘replaced’ by young, non natives. Many die and are not replaced after they
die
I have two trees planted at the Commemorative Grove for my deceased parents.Does the city’s Urban
Forestry program still maintain these trees?
I have only seen one young man out there. There wasn’t anything in the survey about this wonderful
program. I hope it will be a priority in the future!
Full staffing is vital.
I think that adding 10,000 new trees is a good start, but we should be more ambitious with our goals to
transform our city into a beautiful space with plenty of shade, beauty, and animal life that will help sustain
us through the difficulties to come from climate change
The Urban Forestry program has NOT been staffed for over one year. Only one interim city arborist and
one part time temporary tree worker. They have only recently renewed a contract service provider that is
based out of Ventura. There is nothing safe or efficient about the current program.The current state of our
street trees/urban forest is literally an accident waiting to happen. Please look up ISA best management
practices!!
Please check the irrigation system for the oaks along the railroad safety trail.
Too many mature trees are cut down to make it easy for developers, instead project design should be
guided to protect them. It takes years to replace their value with new planting.
Tree planting requires continuous community engagement, volunteerism, and stewardship beyond what
our small City Urban Forest Services team can provide. Therefore, our community would benefit from a
dedicated tree planting organization like Portland's Friends of Trees. https://friendsoftrees.org/
How can the City foster the growth of such an organization?
Removal of the mature and varied species of trees at Palm & Nipomo is an outrage as is removal of trees at
the Westmont property. There is no more park‐like parking lot than at Palm & Nipomo. Replanting with
immature trees requires more water & provides fewer benefits of all kinds for many years until the trees
mature.
The last 3+ years of the SLO Urban Forestry program have been severely understaffed and underfunded.
Either hire 4 full time crew members, or contract it all out. Sidewalk impact from tree roots is a major
problem ‐ cheaper to fix by in‐house crews? As downtown trees age and need replacing, more $$$ will be
needed....
I would love to see an emphasis for the City to plant native trees. In my neighborhood (Sinsheimer) we
have street trees that in not doing well because they are not native and they are infested with aphids. I
would also love to see more natives (trees and shrubs) planted in our parks. Meadow Park is a good
example of a great park with amazing trees (it's a hotspot for birds!) and it could also benefit from even
more native trees and shrubs there. Sinsheimer Park could also become a better habitat for
birds/pollinators with better tree selection. Thank you!
We need a really well‐qualified City Arborist that has a 4 year university degree & perhaps advanced
degrees. You're selling our trees short. Remove Allan Bate, the lead tree killer from the tree committee.
He intimidates and manipulates the others and is the alpha dog.
There is not a 3 person crew! 1 part‐time, temporary employee and a interim City Arborist.
Please be truthful in the way you present this to the community
Refrain from cutting trees downtown
I recently had to remove a tree on our property. The process was good. The tree committee members
listened, the arborist was helpful, and it was easy to see that the city is working to maintain trees citywide.
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We should take a hard look at the species approved for planting within San Luis Obispo.... Native species
are drought tolerant instead of exotics from outside our bio zone...
I would love to see a whole lot less of sprawling parking lots and a whole lot more of city open
spaces/small parks with trees.
Education of the public about how important native trees to the area are, also what is your soil, what tree
is appropriate for your space, how to care for it.
I'm not clear what this survey is supposed to do. Is there really a "debate" about trees? Or are you just
looking for "well, 99% of the people who responded to the survey said they support trees!"
Someone broke a new tree in Islay Park. The city cut it to the stump, but I hope they replace it. Sad that
people vandalize things.
Thank you for wanting to Plant more trees. They take years to mature. What you plant today will be fore
the next generation.
We have had many trees cut down in our neighborhood (on City property) over the past five years. All due
to the trees becoming damaged during strong winds. But the City has never replaced one of these trees!
Don’t they require it of residents who wish to remove their trees? Our property value and our enjoyment
of our home and neighborhood continues to decrease with each tree the City removes and does nothing
replace. We get more freeway noise and more light pollution (headlight pollution, to be specific) with each
removed tree. This survey is so limiting as far as being able to say what topics really matter, so I wish I
could say more, but this one issue in particular really hits home and bothers me greatly!
We have such a beautiful city due to the planting done so long ago. I'm concerned about the cutting down
of trees for all the development going on. These are mature trees going away, and even if we plant
something new, it pales in comparison. We need to plant bigger trees so they can replace those gone
missing. Also, downtown is amazing in large part to the trees/cover. It would be great to expand that
further from the center out to the neighborhoods, and further up the main roads. Also, for the new
development, they should have to plant a mixture of mature and smaller trees.
So happy to see the trees in Laguna Lake getting some much needed trimming, with the dredging project.
We love our trees! I know there are issues with the large ficus (?) trees downtown, but they really are
gorgeous and it is so neat to see such a large canopy.
How trees impact sewer and other infrastructure needs to addressed…funding to help take out root
invasive trees in neighbors along with utility under grounding in older Slo neighborhoods
Too many trees are planted without overhead power lines in mind. Also I see too many trees planted too
close to homes. This is worrisom. I would love to hear the plan on how the city is able to keep up with the
trees in neighborhoods that are encroaching on power lines, damaging foundations and roofs and keep up
with thousands of new trees.
I used to live on Branch Street in SLO ‐ that’s one street where I would love to see dead trees removed so
that new ones may flourish. Avenues lined with trees give a homey, authentic ans welcoming feel ‐ would
love to see more of that along Tank Farm or Higuera (also, where did all the higueras ‐ fig trees‐ go?)
The trees on our street (Jeffery) are significantly over grown, dropping access in yards, and dropping limbs.
The city said we are not scheduled for trimming for 3+ years. I think there needs to be much more routines
matinence on trees to encourage more planting and keep them healthy.
Focus should be on native trees, and maintaining older growth vs removal.
The more trees the better. Ideally, less water intensive trees would be great across the city.
I'm retired and would love to volunteer to help with planting trees/maintaining trees/watering, etc. I think
it's a huge priority. I also think that there probably are many retirees like me who would be delighted to
volunteer to help establish/maintain an urban forest. You have an untapped volunteer base!
I am very interested in the potential for enhancing the synergies between the urban forest and
environmental education at all levels. Any enhancement of open space/urban forests should consider the
opportunity for student engagement and education programs addressing the topics of scientific method,
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climate science education, biodiversity/wildlife, and anything else identified by teachers in the county.
Also, any plans going forward should be laser focused on planning in a way that can be used as a model for
safe planting methods and decision making in the context of high voltage electric distribution/transmission
lines, both underground and above ground.
My HOA (Righetti Ranch) has discouraged residents from planting trees on private property! That should
not be allowed!
I wish there were more tree shaded playgrounds and play areas for children on hot days.
Thanks!
I would like to see an ambitious reforesting effort pursued on the City's hillsides. There are so many bare
or merely grass‐covered slopes all around us, but it is clear that our climate (even during drought) can
support hillside forests. This seems to be the most effective way to both beautify our surroundings while
greatly contributing to carbon sequestration and habitat restoration. The age of widespread grazing is
over, but the damage caused by it has not yet been undone. Though street trees greatly contribute to the
well‐being of residential areas, reforestation of our hillsides would seem to be the most effective
investment in the long‐term.
It is gratifying to witness the maintenance of our trees, although I believe that budget restraints have
meant that our creek/riparian corridor has been neglected in the last 15 years. I remember the community
service program using the labor of corrective institutions to help trim the trees, which benefited the
laborers and the community and nature.
Please use more reclaimed water for maintaining trees and parks.
I was somewhat reluctant at doing this survey given what I consider the reckless destruction of our urban
trees by the city council. The removal of trees for development is constantly justified as necessary to meet
the state housing act. What is also stated to rationalize it is the intent to plant trees elsewhere to replace
these. The fact that "elsewhere" is a place unlikely to be visited or seen by people seems to be a missing
part of the conversation. We need to keep our urban trees for people and other living things that need
them. If we want wildlife in our cities we need to keep our trees. Heck with the state housing act ‐ do you
know how to say No?
If an expert could come to your home and tell you what kinds of trees to plant and where to plant them,
that would be amazing!! I definitely would plant more trees in my front and back yard if I know what and
where!
The city has done a poor job with tree replacement at our parks. Many have been removed because of
disease or damage with no replacement. Many are poorly trimmed or not at all and they grow awkwardly.
Many residents take trees out without permission. Need enforcement and monitoring the tree companies
that do this.
It is essential for our community to have healthy and abundant trees in all areas. Please do not use the tree
survey as a tool to limit trees or to bolster extreme tree trimming. Thank you.
City‐owned property backs up to my property and tree branches reach across into my yard. What types of
maintenance will the city do on these trees?
I think the downtown trees on Higuera are nuisance trees. They bring flies and ruin sidewalks, and the
newer look on Monterey street is much cleaner, easier to navigate and more appealing. I know its not
popular to say this but please remove the trees along Higuera in the shopping district!
A lot of people hate the mess and maintenance on trees. How about access to tree maint. And
landscaping. Especially for the old and others that physically cant.
Reducing energy is an environmental benefit, not socioeconomic…
I heard it’s going away and will be contracted out. They were nice people. Sad the city doesn’t care about
having professional staff anymore.
SLO needs lots more tree cover. SLO needs to stop allowing developers to essentially clear cut well‐treed
sites. The city needs to have more respect for wild things that live in and depend upon trees; I have seen
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city contractors trimming palm trees during owl nesting season, and have seen city repeatedly allow
cutting large trees where hawks nest. The willow habitats along waterways need to be protected; willows
need to be replanted there, and existing groves protected.
I would like the city to plant more edible trees (citrus, feijoa, strawberry/lemon guava, loquat, avocado, fig,
white sapote, persimmon, etc...) along pedestrian & bike paths (e.g., RRST is good candidate). This would
allow residents to better interact with and get value from our trees and paths. Additionally would be a
resource for our food‐insecure population. Use the local California Rare Fruit Growers chapter as a
resource.
Trees are good.
There are several sidewalk and median areas where the trees have been abused or removed and never
replanted ‐ e.g., Bishop St at the entrance to Terrace Hill.
I walk a lot in the city and open spaces and there is a need for more shade!
I’ve seen so many trees being cut down due to lack of proper management such as pruning. Old trees
providing crucial habitat ripped out for new construction with miniature trees being replanted. People
cutting trees without approval and no repercussions
If we focus planting efforts on NATIVE tree species, we can simultaneously create shade/privacy/beauty
etc. for people, AND protect biodiversity. It's a win‐win!
I would like to see more urban forest staff performing much needed maintenance of our city trees.
when i visit a city without trees, i quickly want to leave it. please let's not make this our city. working hard
to educate on how, when to plant trees and offering incentives is a great idea for property owners!
however, where we will really see positive outcomes if the city is acting on the land they manage to plant
more trees. i'm also a strong believer that any new developments need to include not just landscaping but
trees, and ones that thrive in our SLO county environment.
The city urban forestry department is woefully underfunded. Subsequently tree maintenance is not
completed in a timely manor and the trees suffer for it. Urban forest staff is overwhelmed with duties and
cannot be proactive in programming. City inspection of tree protection measures during construction is
non existent due to short staffing. The city should have at least 3 urban foresters plus a 3 person tree crew
to attend to on call tree maintenance issues. Contracting tree crews for regular maintenance is a good
direction to go regarding keeping on schedule.
Need improvement on quality of tree maintenance services, arborists that are able to properly prune and
care for tree health ‐ have seen soooo many trees butchered by tree crews, and killed due to improper
pruning practices.
Provide more funding for the Urban Forest Dept to maintain street trees ‐ public and private. Incentivize
developers to retain large trees in new construction.
The more trees the better ! Part of ANY new residential or large commercial development must include as
many trees as possible, we need them to help us keep our air cleaner & to help us breathe!
Please plant trees and places benches to rest under the shade along the open space and the street on
Orcutt and Sacramento. That open area needs shade and benches. Thanks
Those huge ficus trees need to be trimmed way back and gradually replaced. They take too much water
and are out of scale with the Downtown.
We should consider those spaces outside the city limit but in our county also. They are part of fire
considerations for Slo city.
I am disappointed and feel this survey and effort is a bit late having already lost too many mature trees to
development.
Some of our major thoroughfares (Broad Street is a perfect example) are completely devoid of trees. Broad
Street is horrible — it’s like a freeway. I would love to see streets like Broad have medians fully lined with
trees, except where turn lanes are required.
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Trees are good. The more the merrier. Trees make sense. Do it. Protecting and promoting trees is working
with nature and that is the best guarantee of a healthy, wealthy, prosperous future. The presence of Trees
is the most quintessential expression of our own value and worth. By showing gratitude and respect for
the importance of trees we are showing our priorities and the importance of life and harmony with nature
as our greatest strength.
I love trees and I love forests! I think they have many benefits for communities and I love that the City of
San Luis Obispo is prioritizing trees and urban forestry!
I would love to see trees used to beautify artery streets (johnson, broad, santa rosa, LOVR), and provide
shade and protection to pedestrians/bicyclists.
By moving trees, bike lanes and pedestrians to the middle of these roadways we would see a huge
increase in non‐motor transportation.
Glad you are helping the community gain the many benefits of trees. Thank you!
I’ll repeat, do not allow developers to remove trees. Require them to develop in such a way to preserve
existing trees. What’s the point of planting new trees when mature trees continue to be cut down.
I appreciate how quickly a SLO urban forest employee responded when we had an issue with a tree on the
sidewalk near the driveway to our house (large, broken branch was hanging so low that we couldn't access
our driveway without possible damage to our cars).
I do love when trees separate pedestrians and cyclists from automotive vehicles too....
We love our trees and are excited for more to be in our public spaces. We feel that while most everyone
may have access to the Forestry Services, they may not be aware of that access.
the program needs better funding, haven't seen a street tree list recently, but in the past they have been
bad (poor choices)
Please educate homeowners about tree selection…let’s get away from plum and ficus trees or East‐coast
natives and encourage more of our awesome and hardy native and adapted species!
This is wonderful ‐ let’s plant many more trees! Broad Street between High and Orcutt feels like a highway
and is unpleasant for walking, yet is a key road to use to walk to the Coop, parks, etc. please improve with
more trees (and traffic calming)!!
I know people who say they are afraid to plant trees on their properties because if it turns out to be the
wrong tree for a location, it's almost impossible to get permission to remove it. Several people at a
neighborhood BBQ were in agreement.
If trees are so valuable to the City, why are you permitting a developer to cut down 50 trees off of
Westmont Dr.?
The City should have an aggressive street tree planting and maintenance program. We cannot rely on
homeowners and renters to take care of street trees.
We need more trees. The benefits are immense
Thanks for making trees an important part of the city plan!
The more trees, the merrier!
I hope the city plants as many trees as possible
It would be helpful to include a link on the City website to selectree.calpoly.edu or other similar Matt
Ritter selection tool.
I am not sure what can be done about tree roots that cause sidewalks to be unsafe, but it needs to be
addressed. I believe it can make the city vulnerable to law suits from individuals of a litigious nature who
may trip over an uprooted portion of a city sidewalk.
Trees are important for humanity.
The tree maintenance program is much better in the retail parts of town but in the residential areas it is
lacking. Many street trees in our neighborhoods have gone many years without attention. It is showing
up in trees with dead limbs and misshaped trees due to wind damage.
Also the City is slow on removing dead trees in open spaces and in the street side. And even slower to
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Appendix E: Community Survey 138
replace that tree with another.
It would be nice to see a wider variety of trees. It seems to be when the city plants trees the are all the
same. Then a few years later they do a different tree. It is like they go to Costco and buy a bunch,
regardless location of the tree, then move to another variety.
need to place more trees in multi family unit housing, which are mostly surrounded by cement and low
income.
We use way too much fossil fuel maintaining the city's trees‐I would bet that in the 30 years I've lived here
there has been a multiple of more carbon emitted by vehicles and power tools than any amount of carbon
our trees have captured. The same is true of how most businesses and residences (and all schools)
maintain their landscaping. The number of gasoline powered leaf blowers being used on sidewalks/parking
lots/streets is also kind of horrifying, especially considering many of those are also maintained by street
sweeping vehicles‐public and private.
It's a travesty that the City has systematically been allowing for the removal of thousands of mature trees
for purposes of residential and commercial developments. The increased number of small trees planted in
their place will nowhere near provide the carbon sequester benefit for many years. I find it hypocritical to
act concerned about our Urban Forest while approving the removal of mature trees all over the city to
make it easier for a developer to build. We need to preserve our existing Urban Forest as well as continue
to plant trees to increase it.
mature trees shouldn't be swapped with small trees for developers. Development should build around the
trees = for example the trees on Madonna Road for the development under construction and the
proposed development on Westmont
Too many trees are being cut down for development.
I’m hoping that there’s integrity behind the reasons for creating a survey like this but hah! Will the city
leadership have us rate the importance of water next, can’t wait for that survey:)
We should plant more edible fruit trees as an inexpensive way to provide a social safety net
Efforts seem to be directed toward tree removal rather than planting. Questionable choices of street trees
allowed (oaks by American Riviera Bank).
I had two young trees in front of my house. Same species. One died because the other was stronger and
shaded it. They were planted too close to each other. Maybe more thought can be put into species and
spacing.
There are some very large trees on public and private land that present a clear and present danger to
nearby people, homes and other structures due to damage from storm events and age‐related falling
limbs. How does the city address tree maintenance in those situations?
I'm SO happy the city cares to sustain and hopefully expand the urban forest.
It’s not advisable on downtown City sidewalks due to bird droppings, falling leaves, etc. although they are
attractive and provide shade.
Downtown sidewalks are a hazard due to tree roots pushing up the sidewalks. I have tripped/fallen &
ended up in the E.R. with injuries due to this. Sidewalks need to be redone & some trees need to be
removed.
Total 192 (452 skipped)
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City of San Luis Obispo INVENTORY OVERVIEW
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IMPORTANCE OF A TREE
INVENTORY
It is important to accurately
identify the trees within an
agency’s urban forest. Knowing
the quantities, locations,
species types, and health
conditions of these essential
assets within the community
provides the foundation for
which annual work plans and
budgets are based. Therefore,
having an inventory is critical to
the implementation of an
effective tree care program.
As of June 15, 2022 the data in
ArborAccess determined that
the City of San Luis Obispo’s
inventory consisted of 12,970
owned tree sites located
throughout streets, parks, and
facilities while including data
collection of stumps and vacant
sites. Examples of some of the
information collected for each
tree site is listed below:
• Tree Site Address
• Tree Species Identification
• Diameter Range
• Utility Presence
• Recommended Maintenance
• Removal Priority
• Height Range
• Condition
• Tree Health Concern
• Parkway Size/Type
June 15, 2022
1
City of San Luis Obispo INVENTORY OVERVIEW
Page 644 of 748
+
TREES
12,455
PLANTING SITES
379
RECOMMENDED REMOVALS
127
+ STUMPS
134
2
June 15, 2022
TOP 10 SPECIES & VALUE
Page 645 of 748
June 15, 2022
3
DBH HEIGHT
Page 646 of 748
ROUTINE TRIM
Routine Trim/Grid Trim (10,156 trees)
Regardless of the amount of a community’s tree management budget, systemic tree maintenance
reduces costs in the long term. There are 10,156 trees identified and recommended for routine
trimming. Systematic tree maintenance programs reduce the need for “emergency” maintenance,
help prevent liability problems (such as dead or weak branches that could fail), reduce tree mortality
and improve urban forest health and real value over the long-term.
A systematic tree maintenance program is comprised of pre-designed trimming grids which are
inspected and trimmed as needed in their entirety on a set schedule. By trimming trees on the
street, regardless of size, every resident in that community feels that they have received a service
for their tax dollars. At the same time, the safety and welfare of the community will be enhanced.
*Trees can present a serious safety concern, especially
larger, mature trees. Because many agencies assume
responsibility for a safe public right-of-way, any negligence for
the care of trees impacting the safety of the right-of-way may
fall on the agency. However, by implementing a
comprehensive tree risk management program, the agency
can take steps to limit their liability while keeping the public
safe.
Benefits of Grid Trimming
• Scheduling
• Improved Public Relations
• Equitable Service
• Preventative Maintenance
4
Patrol - Diseased or Declining (114 Trees)
These 114 trees are in decline due to environmental conditions, pests, disease problems, or due to
natural senescence. At the time of data collection these trees had not reached the point where
removal was necessary. In some cases, the condition of these trees may be improved by trimming,
watering, or improved by application of plant health care practices. It is recommended that these
trees go through a process of disease identification and treatment prescription and be patrolled to
determine the timing of treatment and application, or when removal is warranted.
Trim - Poorly Structured (29 Trees)
These 29 trees have been identified as having structural defects that can be improved through
structural pruning. These defects can include codominant stem trees requiring reduction cuts to
reduce the likelihood of failure. This can also include end weight reduction cuts to improve structure.
Young Tree Maintenance (1,703 Trees)
These are newly planted trees that have not been established or had stakes removed yet. These
trees need monitoring, watering, re -staking, fertilizing and structural pruning. This typically ends
when the stakes are no longer needed and they work type should be transitioned to a routine/grid
trim.
June 15, 2022
• Improve Health
• Maintain Capital Asset
• Reduced Liability*
• Efficient Record Keeping
Page 647 of 748
REMOVALS/ INSPECTION
Removal - Stump
(134 stumps)
Removal - Diseased or Declining
(20 trees)
Twenty trees were identified as diseased or
declining and are declining due to pest
infestations, disease or natural senescence.
Removal - Dead Tree
(59 trees)
Dead trees are identified by their species names
where the species can be determined. If they are
not identifiable they are called "Dead Tree." All
dead trees should be scheduled for immediate or
routine removal unless they are considered for
preservation to create suitable wildlife habitat
where conditions for public safety are not a
concern.
Removal - Poorly Structured
(12 trees)
These twelve trees have potentially hazardous
cracks or structural problems that present above-
normal safety concerns, and the potential for tree
failure cannot be mitigated through pruning. Other
examples of poorly structured trees are those that
have included bark located in a primary branch
attachment, which greatly increases the potential
for limb failure in the future.
Removal - Overhead Spacing Criteria
( 1 tree)
Maintained by other agency or HOA
(327 trees)
June 15, 2022
Removal - Seedling or Volunteer
(35 trees)
Trees meeting this criteria were not
intentionally planted by homeowners; they
were grown from seeds, from surrounding
5
Inspect - Recommended Removal
(1 tree)
One poor condition Sweetshade tree has
been recommended for removal by our tree
crew. It may not benefit from plant health
care techniques, and should be viewed by
City staff.
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June 15, 2022
6
The inventory data collected suggests the following
maintenance recommendations which should be
verified by staff.
1. Grid trim schedule to prune all trees on a routine
cycle (Most agencies average between 3 to 5
years).
2. Initiate inspection and mitigation for trees
identified to need patrolling for disease or
decline.
3. Removal plan (evaluate WCA, Inc.
recommendations and determine the agency’s
priorities for phased removals or other
mitigation).
4. Planting plan to fill vacant sites.
5. Provide young tree maintenance to ensure
proper establishment.
CONCLUSION
This information is considered to be a valuable reference for
future budget and maintenance projections. Your Area
Manager and WCA, Inc. can help you create these
projections.
PLANTING
Tree Planting (379 sites)
Based on the criteria provided by the City, WCA, Inc. identified 379 vacant sites that are suitable for
planting. Identification of vacant sites during the inventory collection allows the agency to expand
the urban forest and may assist in obtaining additional grant funding. Vacant site listings from the
inventory can be generated to create work lists and utilized for budget projections. The planting
palette should be referenced when determining the appropriate species to plant based on the
concept of “right tree, right place.”
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Page 650 of 748
City of San Luis Obispo Community Forest Plan
PROFESSIONAL PROJECT REPORT
–
CITY & REGIONAL PLANNING
DEPARTMENT
CALIFORNIA POLYTECHNIC
STATE UNIVERSITY,
SAN LUIS OBISPO
–
JUNE 2022
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City of San Luis Obispo Community Forest Plan C. Hamma
Professional Project Report: Master of City & Regional Planning Program Page 2 of 91
This report was prepared for the City of San Luis Obispo, California in partial fulfillment
of the requirements for the Master of City & Regional Planning degree program,
Department of City & Regional Planning, California Polytechnic State University, San Luis
Obispo.
Christopher C. Hamma
June 2022
Cover photos by Christopher Hamma
Top left: The “Moon Tree” coast redwood, Mission Plaza
Bottom left: Coast live oak woodland below Bishop Peak
Middle right: San Luis Obispo City Hall, 990 Palm Street
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Acknowledgments
The author is grateful to the following individuals for their contributions to this document:
Graduate Committee:
Mike Boswell, Cal Poly San Luis Obispo – City & Regional Planning Department
Bob Hill, City of San Luis Obispo – Office of Sustainability and Natural Resources
Rodney Thurman, Heritage Tree Arboricultural Consulting
Interviewees and Other Individuals Consulted:
Joe Carotenuti, Historian
Michael Codron, City of San Luis Obispo
Ron Combs, City of San Luis Obispo (retired)
Kim Corella, CAL FIRE San Luis Obispo
Greg Cruce, City of San Luis Obispo
Thomas Kessler and volunteer staff, History Center of San Luis Obispo County
Jeff Reimer, Cal Poly San Luis Obispo
Matt Ritter, Cal Poly San Luis Obispo
Nathan Slack, City of Santa Barbara
Bettina Swigger, Downtown SLO Association
Rodney Thurman, Heritage Tree Arboricultural Consulting
Matthew Wells, City of Santa Monica
Anthony Whipple, City of San Luis Obispo
Jenn Yost, Cal Poly San Luis Obispo
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City of San Luis Obispo Community Forest Plan C. Hamma
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Table of Contents
Acknowledgments ......................................................................................................................................... 3
Table of Contents .......................................................................................................................................... 4
I. Vision and Mission Statement .............................................................................................................. 7
A. Vision ................................................................................................................................................. 7
B. Mission .............................................................................................................................................. 7
II. Executive Summary ............................................................................................................................... 8
III. Introduction .................................................................................................................................... 10
IV. Methodology ................................................................................................................................... 12
A. Literature and Urban Forest Plan Review ....................................................................................... 12
B. Stakeholder Interviews ................................................................................................................... 12
C. Historical Archive Review ................................................................................................................ 13
V. Literature Review ................................................................................................................................ 14
A. Urban Forestry Overview ................................................................................................................ 14
B. Valuation of Ecosystem Services ..................................................................................................... 16
C. Carbon Sequestration and Storage ................................................................................................. 17
D. Urban Heat Island Effect ................................................................................................................. 18
1. Urban Tree Canopy ..................................................................................................................... 19
2. Public Health ............................................................................................................................... 19
3. Energy Use .................................................................................................................................. 20
4. The Urban Heat Island Effect and Equity .................................................................................... 22
5. Conclusion ................................................................................................................................... 22
E. Tree Planting Initiatives .................................................................................................................. 22
F. Equity .............................................................................................................................................. 23
VI. Historical Context ............................................................................................................................ 25
VII. Policy Context ................................................................................................................................. 32
A. General Plan Policies ....................................................................................................................... 32
B. Municipal Code (2021) .................................................................................................................... 33
C. 2021-2023 City Goals ...................................................................................................................... 34
D. Climate Action Plan for Community Recovery (2020) .................................................................... 35
E. Conservation Guidelines for Open Space Lands (2002) .................................................................. 35
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F. Multi-Jurisdiction Local Hazard Mitigation Plan (2019) (Lead Agency: San Luis Obispo County) .. 36
H. Downtown Concept Plan (2017) and Mission Plaza Concept Plan (2017) ...................................... 37
I. Presidential Executive Order on Strengthening the Nation’s Forests, Communities, and
Local Economies (2022) .......................................................................................................................... 37
VIII. New Urban Forestry Contracts (2021) ............................................................................................ 38
A. Maintenance ................................................................................................................................... 38
B. Tree Inventory ................................................................................................................................. 38
C. Urban Forestry Organizational Assessment .................................................................................... 38
1. Findings ....................................................................................................................................... 38
2. Recommendations ...................................................................................................................... 39
IX. Key Findings of Stakeholder and Technical Expert Interviews ....................................................... 40
A. Ensure Adequate Funding ............................................................................................................... 40
B. Ensure Adequate Staffing ............................................................................................................... 41
1. City Employees vs. Contractors ................................................................................................... 42
2. Management ............................................................................................................................... 42
3. Volunteer Labor .......................................................................................................................... 43
4. Location within City Organization ............................................................................................... 44
C. Complete Program Analysis and New Tree Inventory; Accrue and Analyze Data .......................... 44
1. Targets ........................................................................................................................................ 45
2. Metrics ........................................................................................................................................ 46
3. Data Analysis ............................................................................................................................... 46
D. Strengthen Maintenance Practices and Clear the Backlog ............................................................. 47
E. Increase New Plantings ................................................................................................................... 48
F. Focus on Sustainability .................................................................................................................... 49
1. Right Tree, Right Place ................................................................................................................ 49
2. Lifecycle Perspective ................................................................................................................... 50
3. Climate Readiness ....................................................................................................................... 52
4. Diversity ...................................................................................................................................... 53
5. Pests and Disease ........................................................................................................................ 53
6. Municipal Tree Lists .................................................................................................................... 55
7. Tree Committee .......................................................................................................................... 56
8. Soil and Infiltration Enhancement .............................................................................................. 57
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9. Safety .......................................................................................................................................... 59
10. Water Conservation ................................................................................................................ 60
G. Address Issues Unique to Downtown ............................................................................................. 61
1. Downtown Concept Plan and Mission Plaza Concept Plan......................................................... 61
2. Downtown’s Big Trees ................................................................................................................ 62
H. Increase Outreach to Officials and the Public ................................................................................. 63
I. Address Equity Issues ...................................................................................................................... 64
X. Goals ................................................................................................................................................... 66
XI. Recommendations .......................................................................................................................... 67
A. Funding ........................................................................................................................................... 67
B. Staffing ............................................................................................................................................ 67
C. Complete Program Analysis and New Tree Inventory; Accrue and Analyze Data .......................... 68
D. Strengthen Maintenance Practices and Clear the Backlog ............................................................. 68
E. Increase New Plantings ................................................................................................................... 69
F. Focus on Sustainability .................................................................................................................... 70
G. Address Issues Unique to Downtown ............................................................................................. 73
H. Increase Outreach to Officials and the Public ................................................................................. 74
I. Address Equity Issues ...................................................................................................................... 75
XII. Next Steps ....................................................................................................................................... 76
XIII. References ...................................................................................................................................... 77
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I. Vision and Mission Statement
A. Vision
The City of San Luis Obispo and its residents serve as the proud stewards of a vibrant,
welcoming, climate-resilient urban forest that maximizes the environmental, social, and
economic benefits provided by trees. The City works hand in hand with a variety of partners,
including community groups and contractors, to ensure that public streetscapes, parks, riparian
corridors, and open spaces support a diverse, thriving tree canopy that improves quality of life
for all in San Luis Obispo, both now and decades into the future.
B. Mission
The mission of the City of San Luis Obispo Community Forest Plan (CFP) is to achieve the stated
Vision by working with and empowering city residents and partners to establish innovative,
science-grounded goals and strategies to protect, expand, and nurture the City’s public tree
cover and the associated benefits over the coming decades.
Roughly 60-year old Indian laurel fig (Ficus microcarpa) trees along Higuera Street in downtown San Luis
Obispo. Photo by Christopher Hamma.
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II. Executive Summary
The City of San Luis Obispo has identified protection and expansion of the city’s urban forest as
a Major City Goal under its 2021-2023 Financial Plan. In addition, as one approach to achieving
carbon neutrality by 2035, the City’s 2020 Climate Action Plan for Community Recovery (CAP)
calls for increasing carbon sequestration in the urban forest through large-scale tree planting. As
such, the CAP proposes preparation of the City’s first-ever urban forest master plan. This is an
initial draft of that document – the City of San Luis Obispo Community Forest Plan.
Activities undertaken in the creation of this document included stakeholder interviews as well as
review of academic literature, other cities’ forest master plans, and historical archives. The
Urban Forest Organizational Assessment commissioned by the City and written by Davey
Resource Group was also reviewed. A high-level summary of selected research results is
provided here:
• The Urban Forest Organizational Assessment and the updated street/park tree
inventory conducted by West Coast Arborists were important first steps in the CFP
process.
• The City currently has approximately 14,000 publicly owned street and park trees.
• Adequate long-term funding, staffing, and contractor management will be critical to
addressing the multi-year tree maintenance backlog and ensuring preservation of
existing, mature public trees in the city.
• The proposed effort to plant 10,000 new trees in the public right-of-way by 2035 (the 10
Tall initiative) will be essential for the creation of a healthy urban forest that serves
future generations of city residents and visitors.
o The primary focus of 10 Tall will be planting native species in City open space
and riparian areas, but streetscapes, parks, and private property also offer
planting opportunities.
o The City will have to work closely with its external urban forestry partners and
their volunteer labor resources to achieve the planting of 10,000 trees.
o These groups will need the ability to access and edit the updated City tree
inventory database for the purposes of recording new tree plantings.
• Metrics and targets will need to be identified in order to evaluate progress toward
goals.
o Examples of potential metrics include percent canopy cover, new tree survival
rate, species and age diversity, and annual carbon sequestration and total
storage.
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• The principles of diversity, equity, and inclusion (DEI) should inform the City’s tree
management and planting activities.
o The City should consider analyzing tree canopy cover, impervious surfaces, and
other land cover characteristics by neighborhood socioeconomic characteristics,
to identify areas in which urban forest benefits may be inequitably distributed.
• The City may want to consider improvements to the municipal code, engineering
standards, and/or management practices around tree planting, removal permitting, and
irrigation.
• Preparation of an urban tree lifecycle plan and a tree planting plan are recommended.
• The City should update its Master Tree List based on ongoing research into climate-
ready urban tree varieties, which are chosen for their tolerance to challenging urban soil
conditions, high heat and aridity, and pests/disease among other factors.
• The role and authority of the City Tree Committee should be reexamined.
• The City must continue to assess the urban forest through the lens of safety, in terms of
wildfire, flood, and hazardous tree risks as identified in the General Plan Safety Element
and the Multi-Jurisdiction Local Hazard Mitigation Plan.
• The City should continue using a variety of outreach methods to foster interest in tree
care and planting among the general public.
Carrot wood (Cupaniopsis anacardioides) trees along Chorro Street, downtown San Luis Obispo. Photo by
Christopher Hamma.
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III. Introduction
Urban forests1 provide a myriad of environmental, social, and economic benefits to a city’s
residents, visitors, and business owners (Dwyer et al., 1992; Tyrvainen et al., 2005; McPherson,
2006; Nowak, 2016; Janowiak et al., 2021). The “green infrastructure” provided by urban trees
and landscaping cleans the air (Nowak et al., 2006), reduces flooding potential, noise, and wind
(Bolund and Hunhammer, 1999; Livesley et al., 2016), cools our buildings through shading and
evapotranspiration (Heisler, 1986; Ko, 2018; McPherson and Simpson, 2003), creates wildlife
habitat (Strohbach et al., 2013), and fights climate change by storing greenhouse gases (GHGs)
in the form of wood (Nowak and Crane, 2002).
Trees beautify our cities (Schroeder, 1989), increase traffic and pedestrian safety (Dumbaugh
and Gattis, 2005), extend pavement life (Burden, 2006), enhance property values and increase
business traffic (Burden, 2006; Staats and Swain, 2020), increase happiness and social
interaction (Kwon et al., 2021; MacKerron and Mourato, 2013; Marselle et al., 2020), and reduce
crime (Kuo and Sullivan, 2001; Schertz et al., 2021). They encourage us to engage in outdoor
recreation, strengthening our physical and mental health (Dwyer et al., 1992; Pretty et al.,
2005). Some trees warrant special treatment because they have outstanding traits or significant
cultural value (Jim, 2017).
These ecosystem services are worth billions of dollars annually to the 83% of Americans who live
in urban areas (University of Michigan Center for Sustainable Studies, 2021). Trees are a good
investment as well – in California, every dollar put into street tree planting and care returns
nearly $6 to its community in ecosystem services and increased property values (McPherson et
al., 2016).
Yet despite growing recognition of the value created by urban forests, the United States is losing
roughly 36 million trees each year due to causes including development, pests and disease,
wildfires, and extreme weather (Nowak and Greenfield, 2018a). San Luis Obispo is vulnerable to
these trends; the City’s roughly 14,000 public street and park trees (West Coast Arborists, 2022)
are at present suffering from a multi-year backlog of deferred maintenance due to staff injuries,
retirements, and the effects of the Covid-19 pandemic.
The San Luis Obispo City Council has declared maintenance and expansion of the urban forest to
be among a suite of Major City Goals in the 2021-2023 Financial Plan (City of San Luis Obispo,
2022a). The Council has also expressed strong support for the City’s 2020 Climate Action Plan
1 While the term “urban forest” typically refers to all trees in a city, both public and private, privately owned trees
usually comprise the large majority – perhaps 80 to 85 percent – of the total (Arbor Day Foundation, n.d.). Because
local governments have limited influence over tree management on private property, the recommendations
presented in this Community Forest Plan deal primarily with the City of San Luis Obispo’s publicly owned street,
park, creek corridor, and open space trees.
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for Community Recovery (CAP) which calls for a new City tree inventory, strategies to revitalize
ongoing tree operations and maintenance, and the planting of 10,000 new trees within the city
by 2035 – as well as for the creation of this strategic Community Forest Plan (CFP; City of San
Luis Obispo, 2022b). The CFP is intended to work together with the City’s General Plan, CAP, and
other guiding documents to support City efforts to become carbon-neutral by 2035 and to adapt
to the disruptive effects of a rapidly changing climate.
San Luis Obispo’s publicly owned urban forest contributes greatly to “the SLO life” and the high
level of environmental quality enjoyed by residents and visitors alike. By highlighting the
valuable benefits provided by the City’s urban trees, acknowledging the challenges faced in their
care, and striving to include the public in adaptive management-based forest planning and
activities, it is hoped that this Community Forest Plan and its future iterations will contribute to
enhanced health and well-being in San Luis Obispo for many years to come.
Terrace Hill and Islay Hill beyond Court Street Plaza in downtown San Luis Obispo. Photo by Christopher
Hamma.
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IV. Methodology
This draft of the San Luis Obispo Community Forest Plan (CFP) was written in partial fulfillment
of the requirements for the Master of City & Regional Planning degree program at California
Polytechnic State University, San Luis Obispo. Specifically, this document is intended to fulfill the
program’s “culminating experience” requirement in the form of a professional project report.
Three research methods were employed in creation of the CFP: review of academic literature
and other cities’ urban forest master plans, internal and external stakeholder interviews, and
perusal of historical archives.
A. Literature and Urban Forest Plan Review
Review of peer-reviewed academic literature provides an important foundation for
understanding the most pressing issues at hand in a given topic area. This work primarily
involved online research, with information from hard copy sources comprising a minor portion.
Scientific and academic journal articles were located and accessed via the Cal Poly Robert E.
Kennedy Library’s electronic databases and via internet search engines. The latter were also
used to locate and access relevant articles published on the web by popular media outlets
including newspapers and periodicals.
Several other municipal urban forest management plans were also reviewed, including those
from the Cities of Davis, San Francisco, Santa Barbara, and Santa Monica.
B. Stakeholder Interviews
Speaking directly with working professionals and academic researchers builds on the insights
obtained via literature review by allowing the interviewer to tap into the latest real-world
knowledge and management best practices and actions, and thus gain crucial understanding of
the relationships between theory and practice.
Prospective CFP interviewees were contacted by e-mail and/or telephone. Those who expressed
willingness to participate were provided with a list of interview questions and were asked to
sign an informed consent document, as required by the Cal Poly Institutional Review Board
(IRB). The informed consent requirement sets out the rights of human research subjects. In this
case the informed consent assured participants that their responses to interview questions,
when referenced within the document being written, would not be tied to any personally
identifiable information. Interviews were conducted via the online video conferencing
application Zoom or by telephone and ranged in duration from 30 to 60 minutes.
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C. Historical Archive Review
Two sources were queried regarding the availability of historical information pertaining to San
Luis Obispo’s urban forest: the History Center of San Luis Obispo County’s research room,
located on the lower floor of the old Carnegie Library adjacent to Mission Plaza, and the
Reference section on the third floor of the current city library at 995 Palm Street in downtown
San Luis Obispo. At the History Center, curated archival materials consisting of photocopied
historical newspaper and magazine clippings were made available for review on the premises.
Similarly, at the public library various books and pamphlets about the city’s history were
perused. In both locations, notes on articles of interest were taken by hand and a smartphone
was used to photograph entire pages for later reference.
Murray Avenue’s unique tree-lined pedestrian median, San Luis Obispo. Photo by Christopher Hamma.
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V. Literature Review
A. Urban Forestry Overview
Urban forests are more important than ever in the face of increasing human population,
increasing migration from rural to urban areas, and worsening impacts from pollution and global
climate change (Tyrvainen et al., 2005). The “green infrastructure” provided by urban vegetation
removes air pollution (Nowak et al., 2006); reduces flooding, erosion, noise, and wind (Bolund
and Hunhammer, 1999; Livesley et al., 2016); gives us energy savings by cooling our homes and
businesses (Heisler, 1986; Ko, 2018; McPherson and Simpson, 2003); provides wildlife habitat
(Strohbach et al., 2013); and stores carbon that would otherwise go into the atmosphere
(Nowak and Crane, 2002).
Trees beautify our cities (Schroeder, 1989), lead to increased outdoor social interaction and
feelings of happiness and safety (Coley et al., 1997; Kuo et al., 1998; Kwon et al., 2021;
MacKerron and Mourato, 2013; Marselle et al., 2020), help us recover from illness (Verderber
and Reuman, 1987) and mental fatigue (Kaplan, 1995), increase property values (by an
estimated 5%; Staats and Swain, 2020) and retail business traffic (Burden, 2006), and reduce
crime (Kuo and Sullivan, 2001; Kuo et al., 2003; Leahy, 2015; Schertz et al., 2021). Parks and
open space that contain urban trees often provide opportunities for public recreation (Dwyer et
al., 1992; Pretty et al., 2005), and individual trees may have historic or other significant cultural
value (Jim, 2017). Forests may even increase rainfall (Meier et al., 2021).
Yet even in the best of circumstances, cities present challenging conditions for tree growth and
survival (Mullaney, 2015; Livesley et al., 2016; Nowak, 2016). Urbanization converts natural land
cover to impervious surfaces, thereby changing natural drainage characteristics and inhibiting
gas exchange and infiltration of water and nutrients into the soil. Additional obstacles to urban
forest health include lack of planting locations and adequate growing space, soil compaction,
high soil salinity and/or unfavorable pH, and high temperatures caused by the urban heat island
effect. Trees can also be damaged by pollution such as contaminated stormwater runoff, the
proliferation of invasive plants, vandalism, and physical interference from infrastructure.
These conditions can stunt trees and plants, limiting their health and lifespan (Lawrence et al.,
2012); research has found that street trees have shorter lifespans than trees in more natural
settings (Smith et al., 2019). The average lifespan of a street tree is estimated at 19 to 28 years;
the survival rate of new plantings ranges from 94.9 to 96.5% (Roman and Scatena, 2011).
In fact, despite growing appreciation of the environmental, social, and economic benefits
conferred by tree cover, the US is losing tree biomass and gaining impervious land cover each
year due to urban and agricultural development, pests and disease, wildfires, and extreme
weather; this trend has accelerated noticeably since the mid-1990s (Cohen et al., 2016). It is
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estimated that over the five-year period from 2009-2014, 1% of all urban trees in the US, or
roughly 36 million trees on 175,000 acres, were lost (Nowak and Greenfield, 2018a). Although
tree growth, natural regeneration, and tree planting associated with urban expansion
counteract this trend to some extent, the net effect is a loss of percent urban tree cover.2
Furthermore, urban green spaces have traditionally been given relatively little consideration in
deference to commercial, residential, and transportation development (Wolf, 2004). To the
extent that municipalities assess their urban forest resources, they often take a narrowly
focused approach by relying primarily on quantification of canopy cover (Kenney et al., 2011).
This approach is overly simplistic, making it unlikely that forest productivity and benefits will be
accurately characterized. Further, a recent review found that municipal parks and recreation
management agencies, stewards of many of the nation’s urban trees, are largely unprepared for
the current and future effects of climate change (Cheng et al., 2021).
These facts point to the importance of both maintaining current urban forests and continually
planning for (and planting) the next one in the contexts of greater urban populations and
increasingly challenging climatic conditions. For forests and the benefits they confer to be
considered “sustainable” (i.e., meeting today’s needs without compromising future generations’
ability to meet their own needs [Keeble, 1988]), the necessary conditions include a healthy tree
and forest resource, community-wide support, and a comprehensive management approach
(Clark et al., 1997). Success in meeting urban forestry goals is most likely in the presence of
holistic, strategic forest planning and management practices that use frameworks of criteria and
indicators like species and age diversity, condition of publicly owned trees, urban forest funding,
staffing, legal tree protections, and management practices (Kenney et al., 2011).
Sustained outreach to the general public is crucial if success is to be achieved. For a taxpayer-
funded program to achieve substantial public support, elected officials and residents must be
convinced that the benefits provided are worth the costs (i.e., “Sustained political support of
such investments is more likely if economic benefits can be demonstrated” [Wolf, 2004]).
Brief examinations of subtopics including carbon sequestration and storage, ecosystem services
valuation, the urban heat island effect, tree planting initiatives, and equity are presented on the
following pages.
2 This is a nuanced point. Although total area of urban tree cover is expected to increase as urban land cover
expands, average percent tree cover in urban areas is projected to decline from 39.4% in 2010 to 32.8% in 2060
(Nowak et al., 2021). Even though newly developed land is often planted extensively with urban trees, in many
cases these plantings do not offset the total amount of pre-existing tree cover that was removed, resulting in a net
loss of canopy cover. This trend is predicted to continue indefinitely as long as urbanization is ongoing.
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B. Valuation of Ecosystem Services
Urban trees provide their many benefits in a more cost-effective way than human-made, “gray”
infrastructure can (Nowak and Greenfield, 2018b). The value of just four urban tree-related
ecosystem services in the United States is estimated at $18.3 billion annually, namely: air
pollution removal ($5.4 billion), carbon sequestration ($4.8 billion), lowered building energy use
($5.4 billion), and avoided pollutant emissions ($2.7 billion). In California alone, $2.5 billion
worth of street trees provide over $1 billion in ecosystem services to state residents each year,
including the removal of 567,748 tons of CO2 annually, equivalent to taking 120,000 cars off the
road (McPherson et al., 2016).
These dollar values can be significant at the city or metropolitan area level as well. For example,
tree cover was estimated to have reduced stormwater storage costs by $4.7 billion and
generated annual air quality savings of $49.8 million in a study of the Washington, D.C. metro
area (Wolf, 2004). In another study, the USDA Forest Service calculated that the City of Santa
Monica, California’s over 34,000 street and park trees are worth $155 million and deliver $5.1
million dollars' worth of benefits to the community annually (McPherson et al., 2015).
Drilling down to the individual tree level, the planting and first three years’ care of a single urban
tree (cost range = $250 to $600) was reported to return over $90,000 in environmental benefits
to its community (Burden, 2006). A 2002 study in Seattle, Washington reported that per-tree
average annual net benefits were $1 to $8 for a small tree, $19 to $25 for a medium-sized tree,
and $48 to $53 for a large tree (Wolf, 2004), although McPherson et al. (2016) reported a figure
of over $110 per tree for this (tree size not specified) in California. Assuming an average annual
tree management cost of $19, every dollar invested in tree planting or maintenance in California
returns $5.82 to its community in ecosystem services and increased property values (McPherson
et al., 2016).
Estimates of the value of ecosystem services are often based on contingent valuation methods.
Contingent valuation is a survey-based means of estimating the economic value of resources,
often environmental benefits (for instance, air pollution removal) that are not typically traded in
economic markets (Jones, n.d.). The results of these studies may be useful for outreach to
elected officials and the public because they translate sometimes arcane, intangible concepts
into a format that is readily understood by all – dollar value.
However, it is important to note that these often-impressive figures do not translate directly
into revenue into the managing agency’s accounts, because they typically consist of avoidance
of costs that would otherwise be borne by others. For example, if a city plants dozens of trees
that eventually reduce household energy bills in a given neighborhood, the savings from those
trees are realized by individual ratepayers, not by the city. On the other hand, from a broader
perspective it can be argued that such projects have high value for all citizens because of the
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many co-benefits that become available as the trees grow, helping to justify the initial and
operational taxpayer-based expenditures.
Table 1 categorizes the many advantages obtained from urban forests by category of recipient:
residents, visitors, business owners, or all people. Obviously, urban forest benefits are widely
distributed and there is much overlap between categories; this simplified representation is only
one person’s subjective interpretation.
Table 1. Urban Forest Benefits by Recipient Category.
Residents Visitors Business
Owners All
Air pollution removal
x
Beautification/aesthetics x x
Carbon sequestration and storage
x
Cooling and energy savings
x
Flooding/erosion/stormwater runoff reduction x
x
Food production (fruit, nut trees) x
Improved physical, mental, and emotional health
x
Increased contentment/happiness
x
Increased outdoor social interactions x x
Increased property value x 1
x 1
Increased retail business traffic
x
Increased traffic and pedestrian safety
x
Longer pavement life
x
Preserved historic or cultural significance x
Reduced crime
x
Wildlife habitat x x
Wind and noise reduction x x
1 If a property owner
C. Carbon Sequestration and Storage
The Intergovernmental Panel for Climate Change (IPCC) has found unequivocal evidence that
since the beginning of the Industrial Revolution, the mass combustion of hydrocarbons and
resulting release of greenhouse gases (GHG) by human civilization has caused significant
warming of Earth’s atmosphere and ocean and land surface temperatures at a rate
unprecedented in at least the last 2,000 years (Allan et al., 2021). The observed results include
more intense, prolonged, and/or frequent heatwaves, heavy precipitation, droughts, and
tropical cyclones.
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Climate action planning incorporates numerous approaches to both reducing carbon emissions
and strengthening communities’ resilience to the effects of climate change (Boswell et al.,
2019). Carbon sequestration and storage, along with improvements in efficiency and
conservation, replacement of fossil fuels with renewable energy sources, and waste reduction, is
an important strategy for reducing GHG emissions (Boswell et al., 2019, pp. 161-162).
Trees and other woody vegetation act as a sink for carbon dioxide (CO2) by fixing carbon during
photosynthesis and storing excess carbon as biomass; this carbon is not released into the
atmosphere until the wood decomposes or is burned (Nowak and Crane, 2002). Globally, forests
sequester nearly 3 billion tons of anthropogenic carbon every year through net growth,
absorbing about 30% of all CO2 emissions from fossil fuel burning and net deforestation
(Canadell et al., 2007).
As of 2002, urban trees in the coterminous USA were estimated to store 700 million tons of
carbon with a gross carbon sequestration rate of 22.8 million tons of carbon per year (Nowak
and Crane, 2002). The total monetary value of this storage was estimated at $14.3 billion, with
an annual sequestration value of $460 million.
This carbon storage capacity will only become more important going forward. Currently, 83% of
Americans live in urban areas (University of Michigan Center for Sustainable Studies, 2021),
which experience high GHG emissions. Furthermore, the area of urban land cover in the US is
expected to more than double from 27.4 million hectares in 2010 (3.6% of total land area) to
66.0 million hectares (8.6% of total land area) by 2060 (Nowak et al., 2021).
Given these facts, it is unsurprising that interest in tree planting initiatives (TPI) as a means of
sequestering and storing carbon has increased dramatically over the past two decades
(Eisenman et al., 2021). However, these activities may be either sinks or sources of carbon
depending on a variety of factors. A 2015 evaluation of the Million Trees LA initiative found that
the program appeared to be on track to becoming a net carbon sink, although success will
ultimately depend on whether the projected 40-year avoided CO2 emissions from energy savings
and biopower are realized, as well as what happens with the lumber and other organic debris
from removed trees (McPherson et al., 2015). Regardless, the authors noted that opportunities
exist in urban forestry to increase net reductions by reducing CO2 emissions from mulch
decomposition, irrigation, water, equipment, and vehicles.
D. Urban Heat Island Effect
Air temperatures are often higher in a city than in its surrounding countryside; this phenomenon
is known as the urban heat island (UHI) effect (Oke, 1982). Different areas within a city can
experience differing spatial and temporal levels of UHI effect due to variations in land cover,
urban geometry, and absorption and emittance of solar radiation (Kim and Brown, 2021).
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UHIs result from the conversion of natural land cover to urbanized surfaces (often impervious
and dark-colored) and are increased by waste heat from buildings and vehicles (Stone et al.,
2013). UHIs cause temperatures to rise by decreasing the availability of water for evaporative
cooling, and by decreasing reflectance and increasing absorption of solar radiation.
The UHI effect is concerning for two primary reasons: its damaging effects on public health, and
its contribution to increased energy demand (McDonald et al., 2020), both of which may be
expected to increase in step with urban population growth. Furthermore, the UHI effect is
exacerbated by global climate change and this effect is expected to continue (McPherson and
Simpson, 2003; US Environmental Protection Agency, 2022). A study of California’s major cities
found that extreme heat events and temperature variances are projected to increase faster than
the rate of increase in mean temperature (Miller et al., 2008).
1. Urban Tree Canopy
Urban tree canopies moderate the UHI effect by reducing air and surface temperatures through
shading and evapotranspiration (McDonald et al., 2020), and they do so in a very cost-effective
way (Stone et al., 2013; Livesley et al., 2016). Urban tree coverage is associated with reduced
temperatures at the city, neighborhood, street, and parcel scales, even in suburban areas with
relatively lower impervious surface coverage than dense urban areas (Elmes et al., 2015).
Factors influencing the efficacy of tree cover in attenuating the UHI effect include land use types
within the city, amount of impervious cover, tree location, tree density, prevailing winds, and
other regional climate differences (McPherson and Simpson, 2003). Areas with vegetative cover
and high-albedo (i.e., high-reflectivity) roofing and paving materials – referred to generally as
‘‘cool materials’’ – are associated with lower surface and near-surface air temperatures in
contrast to sparsely vegetated areas with low-albedo (“dark”), impervious cover; this is due to
increased evapotranspiration and/or an increase in reflected solar radiation (Stone et al., 2014).
Proper placement of trees is important for optimizing the benefits they provide (Heisler, 1986).
Locations that would block rooftop solar panels or would reduce heating by solar radiation
during winter months should be avoided. In addition, attention must be given to species
selection and water supply when UHI mitigation is a primary ecosystem service desired from an
urban forest; for example, in one study Liquidambar styraciflua trees were found to be
approximately 2.5 times as effective at cooling as Eucalyptus camaldulensis trees (Ballinas and
Barradas, 2016).
2. Public Health
The UHI effect contributes to increased morbidity and mortality through dehydration, higher
risk of illnesses such as heat stroke and heat exhaustion, exacerbation of existing cardiovascular,
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pulmonary, and renal diseases, and respiratory problems from greater exposure to ground-level
ozone (Hsu et al., 2021; McDonald et al., 2020). High heat is also associated with loss of labor
productivity and decreased learning (Hsu et al., 2021).
Many urban residents live in old, poorly insulated houses with little to no air cooling capacity,
and therefore face increased risk of heat-related mortality or morbidity as the frequency and
intensity of heatwaves increase due to climate change (Ko, 2018). This is especially true of
vulnerable populations such as the elderly and the disabled.
Extreme heat is believed to cause an average of 12,000 deaths a year globally, although there is
high year-to-year variation depending on weather conditions (McMichael et al., 2004). Heat
waves are the leading weather-related killer in the United States (US Environmental Protection
Agency, 2021), where estimates of average annual deaths from heat range from 600 (Sarofim et
al., 2016) to 1,300 (Kalkstein et al., 2011). Current mortality rates from extreme heat are
expected to more than double by the mid-to-late 21st century (Stone et al., 2014).
Achieving the 2°C maximum warming threshold called for in the Paris Agreement could avoid
between 70 and 1,980 annual heat-related deaths per US city during extreme events (30-year
return period) (Lo et al., 2019). Similarly, achieving the 1.5°C threshold could avoid between 110
and 2,720 annual heat-related deaths. One study researching heat-related mortality in three
large US cities (Atlanta, Philadelphia, and Phoenix) found that vegetation and albedo
enhancement could offset projected increases in deaths from heat by 40% to 99% across the
three regions (Stone et al., 2014).
A study of urban tree cover across 97 American cities found that trees reduced heat-related
mortality by an estimated 245 to 346 deaths annually at a value of $1.0 - $2.4 billion per year
(McDonald et al., 2020). Extrapolated to all US urban residents, annual avoided mortality might
be 1,030 - 1,454 deaths, valued annually at $5.3 - $12.1 billion.
Interestingly, however, while heat-related mortality is projected to keep increasing, the value of
tree cover for reducing deaths seems to have declined significantly in recent decades due to
increased use of air conditioning (McDonald et al., 2020).
3. Energy Use
The UHI effect increases demand for electricity, largely to power air conditioning, and can
therefore increase carbon dioxide emissions from fossil fuel power plants (McPherson and
Simpson, 2003; Nowak, 2016). UHIs also increase municipal water demand as residents attempt
to keep landscaping alive.
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Trees can increase, decrease, or have little effect on energy use depending on general climate,
building type, tree species, and tree location (Heisler, 1986). Tree shade reduces building energy
demand for air conditioning by reducing solar radiation on walls and roofs and lowers ambient
temperature through evapotranspiration; trees can also reduce heating demand by blocking
wind (Ko, 2018).
The magnitude of reported energy savings varies widely depending on climate, method, data,
and assumptions for buildings and trees. A building with adjacent trees uses 2.3% to 90% less
cooling energy, mostly through shading effects, and 1% to 20% less heating energy through
windbreak effects, in comparison to buildings without trees (Ko, 2018). A summary of research
data suggests that the maximum potential annual effect of trees on energy use in conventional,
single-family houses Is about 20 to 25% compared to the same house in the open (i.e., without
nearby trees) (Heisler, 1986).
The density and spatial arrangement of the urban forest also affect the ability to obtain this
cooling effect. The combined energy savings effect of many trees in an area is much greater
than that from a single tree or a single heavily treed property on a mostly tree-free street
(Heisler, 1986). When large trees are well distributed throughout a neighborhood, all of the
trees together may have a significant impact on temperature and energy use in buildings,
particularly in summer.
Consistent with most large U.S. cities, the vast majority of land cover change in the Atlanta
metropolitan region in recent decades has occurred outside of the central-city core (Stone et al.,
2013). Yet, despite this growth pattern, temperatures in the core have continued to increase at
a higher pace than in nearby rural areas, resulting in rapid growth of the city-center heat island
even in the absence of significant land use changes. Even so, suburban tree cover was found to
provide a heat reduction benefit to nearby central city areas (Stone et al., 2013). Similarly, under
calm wind conditions, the cooling benefit of a large park in the hot urban environment of Tokyo,
Japan extended 200 meters downwind into surrounding neighborhoods (Sugawara et al., 2016).
As of 2003, in California approximately 177.3 million urban trees were reducing annual air
conditioning energy use by 2.5% (roughly 6,400 GWh) for savings of $485.8 million, out of total
tree-affiliated savings of approximately $778.5 million per year (McPherson and Simpson, 2003).
Yet, at the same time, 241.6 million empty planting sites were tallied (i.e., only 42% of all
potential tree planting sites in California cities were filled). Planting 50 million trees to shade
east and west walls of residential buildings was projected to reduce cooling need from air
conditioning by 1.1% and peak load demand by 4.5% over a 15-year period (McPherson and
Simpson, 2003). Given California’s high dependence on electricity imported from other states
and ongoing episodes of power demand exceeding supply (resulting in, for example, rolling
blackouts during heat waves), the above findings highlight an opportunity to improve grid
stability and resilience.
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4. The Urban Heat Island Effect and Equity
Low-income and/or heavily minority-occupied urban neighborhoods in the United States
contain significantly fewer trees and other landscaping, more impervious land cover (thus, fewer
opportunities to plant), and are warmer than newer and/or higher-income neighborhoods,
leading to elevated risk of heat-related mortality and heat illnesses as well as higher energy
costs (Hsu et al., 2021; Jesdale et al., 2013; Watkins and Gerrish, 2018).
In the US, this situation is largely the legacy of historical discrimination against racial and ethnic
minorities, particularly in the form of redlining, the historical practice of denying home loans or
insurance to residents based on the racial composition of their neighborhood (Hoffman et al.,
2020; Locke et al., 2020; Nowak et al., 2022; Wilson, 2020). Nationwide, land surface
temperatures in historically redlined areas are approximately 2.6 °C warmer than in non-
redlined areas (Hoffman et al., 2020). Regionally, southeastern and western cities display the
greatest differences while midwestern cities display the least.
5. Conclusion
A comprehensive heat management strategy, focused on increased forest cover both within and
beyond the municipal boundaries of a large U.S. metropolitan region, is recommended to
significantly reduce warm season temperatures (Stone et al., 2013).
E. Tree Planting Initiatives
The United States has a long historical tradition of municipal park and street tree planting,
beginning in the mid-19th century and increasing in the early to mid-20th century after the loss of
millions of American elms (Ulmus americana) to Dutch elm disease (Ophiostoma spp.)
(Lawrence, 2006). In 1976, the Arbor Day Foundation launched its Tree City USA program, which
now includes over 3,400 member communities (Arbor Day Foundation, 2022).
Municipal tree planting initiatives (TPI) are a form of urban greening that have gained popularity
both in the US and worldwide in recent decades as a means of improving urban quality of life,
while also constituting one of the most effective responses to the global climate crisis through
increased carbon sequestration and storage (Bastin et al., 2019; Pincetl et al., 2013; Eisenman et
al., 2021). Examples include the Million Tree Initiative (e.g., Million Trees NYC, Million Trees LA,
Chicago Region Trees Initiative) (Young and McPherson, 2013), and even a Trillion Tree
Campaign (Trilliontreecampaign.org, n.d.).
However, uncertainties in funding and long-term stewardship surround these large-scale
initiatives (Young, 2011). TPIs are often promoted by elected officials such as mayors, and thus
may be vulnerable to shifting political leadership (Campbell, 2017). Furthermore, TPIs differ
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from traditional urban forestry activities in that while the latter have historically been the
domain of the public sector alone, TPIs are commonly initiated and funded by nonprofit
organizations and grassroots campaigns in partnership with municipalities (Young and
McPherson, 2013). This lack of institutionalization and traditional infrastructure funding raises
concerns over the feasibility of using non-public sector actors – often, untrained volunteers – to
make the necessary long-term stewardship commitments (watering, pruning, mulching) that are
required if newly planted trees are to survive.
The success of TPIs may also be affected by differing expectations on the part of tree planting
leadership vs. the urban residents whose support is solicited; please refer to Section V.F, Equity,
for details.
Not everyone is convinced in the efficacy of mass tree planting campaigns. Some researchers
believe instead that promoting natural regeneration and emphasizing local/indigenous
stewardship will result in stronger, more diverse forests that are better at providing the desired
environmental and other benefits in the face of intensifying droughts, insects, wildfires, and
logging pressure (Rosza, 2021; Rosza, 2022).
In conclusion, because the success of TPIs has rarely been measured (Danford, 2014), their
ability to achieve desired outcomes over years or decades is unknown (Roman, 2014).
Furthermore, when tree-planting entities do attempt to assess outcomes, they commonly use
somewhat limited metrics such as tree survival rate and percent canopy cover. Taking a larger-
scale, more holistic look could be informative and might include the measurement of factors
related not only directly to trees and forest characteristics, but also to soils, climate/
atmosphere, built environment, tree care/maintenance, social characteristics of urban spaces,
and human decisions and governance (Ordoñez et al., 2019).
F. Equity
Many studies have shown that urban tree cover is associated with factors such as income, race,
ethnicity, and education. Significant positive correlations exist between poverty, minority
populations, and disproportionate exposure to environmental degradation and the effects of
climate change; this situation has led to the rise of the environmental justice (EJ) movement
(e.g., Landry and Chakraborty, 2009).
Low-income and/or minority-dominated neighborhoods commonly have less landscaping
(including trees) and fewer opportunities for outdoor recreation than more affluent
neighborhoods, leading to poorer health outcomes and disproportionately high energy bills
(Elmes et al., 2017; Gerrish and Watkins, 2018; Moskell and Allred, 2012; Schwarz et al., 2015;
Watkins and Gerrish, 2018). One study found that in 37 US cities, high-minority, historically
redlined neighborhoods contain approximately half the amount of tree canopy cover as newer
housing stock with primarily white residents (23% vs. 43%) (Locke et al., 2020).
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Furthermore, not only do disadvantaged groups suffer greater exposure and susceptibility to
unfavorable environmental conditions than wealthier segments of society, but they have less
financial ability to cope with and recover from disasters and thus become even more vulnerable
to climate-related disasters over time in a vicious cycle (Islam and Winkel, 2017).
One obvious solution for cities, although not a panacea, would be to prioritize tree planting in
low-income neighborhoods. Counterintuitively, however, this type of policy has often failed and
resulted in complaints being directed toward municipal governments in Los Angeles, New York,
and other cities (Battaglia et al., 2014; Pincetl, 2010; Carmichael and McDonough, 2019). One
study found that the lowest survival and growth rates of newly planted urban trees were in
those planted by public housing groups (Jack-Scott et al., 2013).
In some cases, these failures have been the result of policy and funding difficulties as well as
limited space available for planting in dense urban areas (Danford et al., 2014). However,
another significant reason for the failure of urban tree plantings is that decisions around such
programs have traditionally been made at the local governmental level in a top-down,
hierarchical fashion by organizers who are overwhelmingly white and highly educated, often in
contrast to the overall demographic characteristics of the cities and neighborhoods in which
they work (Campbell et al., 2016).
Failure to consult affected residents about proposed changes in their neighborhood sends a
message that their opinions are not valued (Moskell and Allred, 2012; Westphal, 2003). Perhaps
because of this long-standing feeling of neglect in marginalized communities, many urban
residents are not interested in participating in tree planting or care (Moskell and Allred, 2013),
and community leaders and urban forestry professionals struggle to engage them. This could
change if planners made an effort to address structural inequities in the built environment with
their programs instead of focusing solely on promoting sustainability (Flocks et al., 2011).
In summary, municipal authorities must try to develop stronger, trusting relationships with
underserved communities by meaningfully including those communities in decisions affecting
their neighborhoods prior to project implementation. Aside from listening to local residents,
further recommendations include:
• Determine what motivates the intended recipients most (e.g., environmental concerns
vs. neighborhood quality of life?) and tailor the program to meet those priorities
• Consider partnering with one or more organizations that already have experience
facilitating an inclusive process
• Understand that even an apparently successful project may not be valued by all, and
cannot transform a distressed neighborhood alone (Westphal, 2003).
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VI. Historical Context
Due to its geographic location and climate, the San Luis Obispo area has historically had minimal
native tree cover (Seymour, 1986, p. 50). The Chumash people who occupied what is now the
city of San Luis Obispo for over 10,000 years likely lived in a landscape dominated by grassland
and chaparral, with relatively minimal patches of woodland containing coast live oak (Quercus
agrifolia), California bay laurel (Umbellularia californica), and toyon (Heteromeles arbutifolia);
riparian trees such as California sycamore (Platanus racemosa), arroyo willow (Salix lasiolepis),
and cottonwoods (Populus spp.); and perhaps half a dozen other tree species. However, as a
result of the planting of many thousands of non-native trees in San Luis Obispo over the past
century and beyond, the area now contains far more trees (and tree species) than at any
previous time in human history (Seymour, 1986, p. 50).
The era of Euroamerican settlement and urbanization in the San Luis Obispo area began 250
years ago with the establishment of Mission San Luis Obispo de Tolosa in 1772. The arrival of the
missionaries saw the beginning of landscape conversion to agricultural and eventually urban
uses. Up to half of the area’s native tree cover may have been lost fairly quickly, as there was a
continuous need for heating and cooking fuel. Historical records also indicate that early on, logs
were hauled in from elsewhere in order to continue with construction on the mission buildings,
implying that lumber was in short supply locally (Carotenuti, 2006).
With the establishment of the Mission, the missionaries began to plant olive (Olea spp.), fig
(Ficus carica ‘Mission’), and pear (Pyrus spp.) trees brought from Mexico as cuttings, as well as
grapes (Vitis vinifera) and prickly pear cactus (likely Opuntia ficus-indica). Olive oil and wine
were needed for use in religious ceremonies. The missionaries were familiar with agricultural
practices in dry climates and understood the importance of water conservation (Seymour, 1986,
p. 50); nevertheless, food insecurity and deprivation were never far off for the Mission’s
inhabitants. Drought and insect infestations intermittently caused the failure of fruit and grain
crops (Carotenuti and Olson, 2004).
In the mid-1830s the missions were secularized by the Mexican government. Despite the
resulting chaos experienced by the residents, including poor treatment by corrupt bureaucrats
and army soldiers who were little better than criminals, Mission San Luis Obispo never ceased
being an active church. The Mission was returned to the charge of the padres in the 1840s and
its buildings and grounds, although neglected, never fell into complete ruin as did those at some
of the other missions (Carotenuti and Olson, 2004; Engelhardt, 1933; San Luis Obispo County
Historical Society, 1972).
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Excerpt from Harris and Ward’s 1870 map of downtown San Luis Obispo; the Mission is seen near the
bottom between Broad and Chorro, with the Mission orchard to the north. Photo by Christopher Hamma.
By the post-Civil War era, tree planting and creation of park-like landscapes had begun to
capture the public’s imagination in the US, thanks in part to the design and construction of New
York’s Central Park by Frederick Law Olmsted and Calvert Vaux between 1858 and 1876
(Blackmar and Rosenzweig, 2018). In San Luis Obispo, newspapers such as the San Luis Obispo
(Weekly) Tribune sang the praises of urban trees in their pages and lamented the general
citywide lack of them, citing their beauty, their “sanitary value” as air-purifying sources of “relief
and coolness,” and their usefulness as sources of lumber, fruit, and medicinal products (e.g.,
eucalyptus oil) – not to mention their ability to increase the value of one’s real estate by
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anywhere from 20 to 100%(!) (e.g., San Luis Obispo (Weekly) Tribune, November 16, 1872, p.2;
San Luis Obispo Breeze, February 18, 1898, p.2).
Breathless commentaries on the virtues of blue gum (Eucalyptus globulus) and exhortations to
grow this species in large quantities to fuel an anticipated lumber boom were regularly seen in
print in the 19th and early 20th centuries (e.g., San Luis Obispo (Weekly) Tribune, November 2,
1872, p. 2). Unfortunately for prospective timber barons, blue gum turned out to be a less than
ideal candidate due to its tendency to split and warp while drying, and the boom fizzled.
Meanwhile, regarding fruit trees one newspaper editor opined that “In a few years hence, the
orange groves of San Luis Obispo will be as celebrated as those of Los Angeles or San
Bernardino” (San Luis Obispo (Weekly) Tribune, February 9, 1883, p.1).
Yet, then as now, it was clear that not everyone was in agreement when it came to urban trees.
A mid-1870s news brief stated:
The City Council at its last meeting ordered the removal of all the trees standing in
Higuera Street between Morro and Osos Streets. These trees have long been a nuisance
and their removal will greatly improve the appearance of the thoroughfare which they
have long obstructed (San Luis Obispo (Weekly) Tribune, December 7, 1878, p.5).
Further complaints of the day included the following:
• Untrimmed tree limbs forcing people to walk into the street to avoid them
(“…particularly disagreeable in wet weather” – San Luis Obispo (Daily) Tribune,
November 1, 1883, p.3)
• Numerous instances of miscreants felling and girdling roadside shade trees (“...The
name of the ass who authorized this public outrage is not known” – San Luis Obispo
Evening Breeze, March 30, 1896, p.2)
• Merchants being showered with cottonwood debris at the corner of Higuera and Chorro
Streets (“…on windy afternoons the down from the trees is blown into their places of
business… They are anxious to have the trees cut down or some other means taken to
dispose of the nuisance” – Daily Telegram (San Luis Obispo), June 1, 1911, p.5)
• And finally, would-be olive oil tycoons experiencing recurring infestations of “scale bug,
which is a sort of terrestrial abalone… Will not somebody try the experiment of spraying
the trees with a solution of whale oil soap?” (San Luis Obispo (Daily) Tribune, July 14,
1883, p.3).
And, also as today, some people just couldn’t be bothered to be responsible members of the
community:
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EDS. TRIBUNE: …It is well known that many of our citizens have been to considerable
expense in the way of planting shade trees and beautifying the streets as well as their
own property. Many of these are growing finely, but the young shoots or sprouts are
constantly being bitten off by stock which are allowed to run at large in our streets. Who
is to blame? SHADE TREE. (San Luis Obispo (Weekly) Tribune, June 8, 1872, p.2).
Fortunately for them, the owners of these free-spirited livestock appear to have arrived on
scene too late to become ornaments on San Luis Obispo’s hanging tree, on Chorro Street
between Islay and Leff Streets:
…Miss Ella Villa… has the word of her late grandmother that the “Hang Tree” bore its
quota of “fruit.” “Grandmother told me many a time of having seen bodies swinging
from that great tree when she came into town from her farm at Edna,” Miss Villa said.
(Telegram-Tribune, 1941).
Over the years, many varieties of non-native trees and plants were brought to San Luis Obispo
and planted: eucalyptus, acacia, hakea, pittosporum, melaleuca, leptospermum and bottle
brush from Australia; geraniums, aloes, and bird-of-paradise from South Africa; loquats and
crape myrtles from China; pepper trees and bougainvillea from South America; oleanders,
arbutus, and jasmine from the Mediterranean; guava from Brazil; myoporum from New Zealand;
deodar cedar from Asia; and cypresses and pines from Italy as well as other parts of California
(Seymour, 1986, p. 51).
Regardless, for whatever reason, downtown San Luis Obispo remained tree-impoverished for
decades. Historical photographs of downtown San Luis Obispo taken prior to the 1960s show an
urban setting that looks utterly desolate in comparison to its current verdant state. In the words
of one resident who moved to the city in 1930, “…there were almost no trees at all downtown…
It was very barren and I couldn’t get over it” (Fairbanks, 1989).
However, starting in the late 1950s a beautification program led by City Councilman R.L. Graves
resulted in the green downtown we are familiar with today (Carotenuti, 2006). City Engineer
(later Mayor) Dave Romero organized the effort. It is worth noting that at the time,
environmental reasons for planting street trees (e.g., air pollution removal, carbon
sequestration) were either unknown or of relatively little importance to the public; aesthetics
were the primary motivation for planting them (Bingham, 1968).
City Parks Director William Edward Flory was featured in a November 1963 Tribune article,
describing his activities in planting 43 carrot wood (Cupaniopsis anacardioides) trees along
Chorro Street in downtown (Middlecamp, 2021). Seventy more trees along Higuera Street
between
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“Higuera Street then and now.” Photo dates unknown. Source: Davey Resource Group Urban Forestry
Organizational Assessment, 2021.
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Santa Rosa and Nipomo Streets soon followed. A 1989 Telegram-Tribune article noted, “…Now,
400 carrot woods, Indian laurel figs, evergreen pears, Brisbane boxes, ornamental avocados, and
holly oaks sprout from concrete sidewalks, creating canopies of shade and splashes of greenery”
(Fairbanks, 1989).
In the 1963 feature, Flory stated that natives like coast live oak and California sycamore were
not chosen for planting downtown because of their large size when mature, which would almost
certainly result in sidewalk damage (ironically, in 1991 the City designated the California
sycamore as the official City Tree). Despite this, some of the trees that were planted at that time
and now dominate downtown present the same problem, as well as other concerns, due to their
size, species, or other factors.
During the late 1960s and early 1970s, the segment of Monterey Street in front of the Mission
was torn out and the area was converted into a car-free pedestrian square, creating today’s
Mission Plaza (Clark, 1979). Beautifying the plaza with landscaping was a high priority for the
City. Trees were moved from Santa Rosa Park and San Luis Coastal Unified School District
property to the Plaza, including (from the latter) two old olive trees that had once been part of
the Mission’s olive grove.
The City revived its Heritage Tree program in the 1980s (O’Sullivan, 1986). Currently, 16
properties within the city limits host one or more designated Heritage Trees (Andrews, N.D.).
The City defines these as trees that “played an important part in the day-to-day lives of our
forefathers” and which made significant contributions, have historical value, and hold significant
arboricultural interest (City of San Luis Obispo, 2022d).
Perhaps the highest-profile Heritage Tree in San Luis Obispo at present is the “Moon Tree,” a
coast redwood (Sequoia sempervirens) that was planted as a sapling near Mission Plaza for the
national Bicentennial Celebration in 1976, five years after having visited the moon as a seed
aboard Apollo 14 (Sheeler, 2018). The planting of this tree prompted a congratulatory telegram
to City officials from President Gerald Ford, who called it “a living symbol of our spectacular
human and scientific achievements” (Groshong, 1987).
Other notable urban forest events in San Luis Obispo include:
• In 1912, D.J. Riley of Riley’s Department Store asked his neighbors on Mill Street if they
would mind him planting trees along their block, between Pepper and Johnson. There
were no objections. Those camphor trees (Cinnamomum camphora) are now 110 years
old, make the block uniquely beautiful, and indeed define the Mill Street Historic
District. At some point the City had to start heavily pruning the trees because truck and
bus traffic was constantly knocking branches off, and there have been instances of
sewer line invasion by roots, but the residents love the trees regardless (Zeuschner,
1989)
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• Pioneer son Warren Sinsheimer made the Tribune’s front page in 1963 for his plan to
preserve the very old sycamore, olive, and eucalyptus trees at Marsh and Osos Streets
while constructing the new Sinsheimer Trust Building and simultaneously repairing the
dilapidated Marsh Street Bridge. The olive trees were part of the original Mission olive
grove; some of them were planted in 1772 (San Luis Obispo Tribune, October 24, 1963,
p.1)
• In 1980, a 210-year old Mission fig on Chorro Street between Peach and Walnut Streets
fell in a windstorm. This tree had been planted by the friars in 1770 (Scott, 1980,
February 8). After its demise, over 1,000 cuttings were potted by Cal Poly’s Ornamental
Horticulture Department, intended for sale and planting around town (Scott, 1980,
February 23)
• In 1989, the City’s Commemorative Grove was established at Laguna Lake Park. Nine
commemorative trees and 38 windbreak trees were planted for the occasion (City of
San Luis Obispo, 2022c)
• On November 26, 2007, the City Tree Committee approved the removal of the famous
45-year old floss silk tree (Ceiba speciosa) in front of Mission San Luis Obispo due to its
roots cracking the walls of a planter attached to the mission – its second offense after a
similar episode in the early 1980s (Fairbanks, 1989). Relocation was considered but was
ruled out due to concerns that 18th century tiles under the tree, and perhaps other
archeological artifacts, could be damaged. The tree was removed in June 2008. As with
the Mission fig discussed above, it was expected that “…1,000 floss silk clones (would)
be available for planting in the city by the end of summer” (San Luis Obispo Tribune
staff, June 13, 2008).
• Within the past few years, some high-profile tree removals have raised controversy in
town:
o In 2017, 49 trees up to 100 years old were removed at 71 Palomar Avenue to
make way for a student housing complex (Schmidt, 2016); the City required 2:1
replacement for the removed trees (City of San Luis Obispo, November 13,
2017)
o Also in 2017, a large, beloved 85-year old eucalyptus (the “Big Tree”) and
several other trees including a large oak were removed at San Luis Obispo High
School in light of plans for new construction on the campus (Leslie, 2017). Over
1,600 protest comments were posted online in an effort to save the eucalyptus,
but the tree was considered a safety hazard and had grown into the school’s
main sewer line, causing blockages (Wilson, 2016; Ferreira, 2017).
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VII. Policy Context
The CFP is intended to align with the City of San Luis Obispo General Plan, Municipal Code,
Major City Goals, and other applicable plans and policies. Selected examples are listed on the
following pages.
A. General Plan Policies
Land Use Element, Sustainability Policy 9.9 - Renew the Urban Forest:
The City shall develop a long-term tree planting program to beautify the city, mitigate increased
residential density, address die-off, and combat air pollution and global warming.
Land Use Element, Sustainability Program 9.10 - Urban Forest:
The City shall update the master tree plan and develop recommendations to renew and maintain
the urban forest and plant more trees.
Conservation and Open Space Element, Materials Policy 5.5.2 - Promote City Materials Reuse
and Recycling:
The City will manage its operations to foster reuse and recycling by:
D.) Making wood from tree removal available for mulch, milling, pulping or heating,
depending on its characteristics and the volume available, while avoiding the
introduction or spread of invasive, non-native species and pathogens. Selection of trees
for City streets, parks and grounds will take into consideration their eventual disposal.
Conservation and Open Space Element, Natural Communities Policy 7.5.1 - Protection of
Significant Trees:
Significant trees, as determined by the City Council upon the recommendation of the Tree
Committee, Planning or Architectural Review Committee, are those making substantial
contributions to natural habitat or to the urban landscape due to their species, size, or rarity.
Significant trees, particularly native species, shall be protected. Removal of significant trees shall
be subject to the criteria and mitigation requirements in Chapter 8.6.3. Oak Woodland
communities in the Greenbelt and in open space areas shall be protected.
Conservation and Open Space Element, Natural Communities Policy 7.5.3 - Heritage Tree
Program:
The City will continue a program to designate and help protect “heritage trees.”
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Conservation and Open Space Element, Views Policy 9.1.4. - Streetscapes and Major Roadways:
The City will…
B.) Encourage the creation and maintenance median planters and widened parkway
plantings.
C.) Retain mature trees in the public right-of-way.
D.) Emphasize the planting and maintenance of California Native tree species of
sufficient height, spread, form and horticultural characteristics to create the desired
streetscape canopy, shade, buffering from adjacent uses, and other desired streetscape
characteristics, consistent with the Tree Ordinance or as recommended by the Tree
Committee or as approved by the Architectural Review Commission.
Safety Element, Wildland Fire Safety Policy 3.1B:
New subdivisions shall be prohibited in areas of “Very High” wildland fire hazard as shown in
Figure 2 unless part of conservation or open space acquisition program. Development of existing
parcels shall require a development plan to manage fuels, maintain a buffer zone, and provide
adequate fire protection to the approval of the Chief Building Official. The development plan
must be consistent with Policies required by the City’s Conservation and Open Space Element.
Safety Element, Hazardous Trees Policy 8.0:
Minimize danger to people and property from trees that are weakened and susceptible to falling
or limb loss during storms.
Safety Element, Hazardous Trees Program 8.1:
The City will identify, and maintain or remove, trees on City property to minimize hazards, and
will work with property owners to do the same.
B. Municipal Code (2021)
Chapter 12.24 – Tree Regulations
12.24.010 – Purpose and Intent.
A. The public interest and welfare require that the city establish, adopt and maintain a
comprehensive program for installing, maintaining and preserving trees within the city.
B. This chapter establishes policies, regulations and specifications necessary to govern
installation, maintenance, removal and preservation of trees to beautify the city, to purify
the air, to provide shade and wind protection, add environmental and economic value and
to preserve trees with historic or unusual value.
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C. It is the policy of the city to line its streets with trees and to conduct a consistent and
effective program for maintaining and preserving these trees. This policy provides for
planting trees in all areas of the city and for selecting appropriate species to achieve the
city’s goals. It is also the policy of the city to protect and preserve all desirable trees,
wherever they are located. It shall be the duty of the director to enforce, implement and
carry out this policy and the provisions of this chapter.
D. It is the policy of the city to encourage new tree planting on public and private property and
to cultivate a flourishing urban forest with an emphasis o n native and drought tolerant
species.
E. Trees are essential to the community’s well-being and the care and planting of all trees will
be done in a manner consistent with city policies and standards. (Ord. 1544 § 1 (part), 2010)
12.24.020 – Tree Committee.
A. The tree committee shall act as an advisory body to the director and the city council on all
matters related to trees in San Luis Obispo.
B. The tree committee membership shall be governed by tree committee bylaws, as approved by
the council. (Ord. 1589 § 1, 2013: Ord. 1544 § 1 (part), 2010)
12.24.160 – Heritage Trees.
A. The city recognizes the important role trees have played in the history and development of
San Luis Obispo and recognizes that a wide variety of trees can grow in its unique and temperate
climate.
B. Any healthy tree within the city limits may be proposed as a heritage tree. The city arborist
and tree committee review each proposed heritage tree and, with the owner’s consent,
recommend suitable candidates to the city council for official designation as heritage trees.
C. The city shall protect and maintain all designated heritage trees. Heritage trees shall be
pruned according to a schedule developed and approved by the public works director. All interim
maintenance shall be the responsibility of the property owner. (Ord. 1544 § 1 (part), 2010)
C. 2021-2023 City Goals
Major City Goals: Climate Action, Open Space & Sustainable Transportation – Expectation #3:
The City will engage in projects and initiatives that contribute positively toward integrating best
practices for urban forestry throughout the community and City landscape in order to accrue the
multiple benefits that trees provide including shading and cooling, beautification, habitat,
stormwater retention, and carbon sequestration.
City Goal Strategy 4.3 ‐ Preserve and enhance open space and the urban forest:
… The City is also long recognized for the past 37 years as part of the Arbor Day Foundation’s
“Tree City USA” network that extends across the entire country. This Major City Goal provides an
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opportunity to focus renewed efforts on the City’s cherished urban forest by completing the first
ever Urban Forest Master Plan, providing a comprehensive update of the City’s tree inventory
and assessing overall tree canopy, implementing a contemporary tree database and tracking
system, working towards the goal of planting 10,000 new trees by 2035 in partnership with
ECOSLO and the community, and moving towards an integrated approach to urban forestry that
accounts for street trees, park trees, open space trees, and riparian trees in a more holistic
manner.
D. Climate Action Plan for Community Recovery (2020)
The 2020 Climate Action Plan for Community Recovery (CAP; City of San Luis Obispo, 2022b) sets
out the City’s proposed approaches to achieving carbon neutrality by 2035, organized into six
“pillars.” Each pillar has a long-term goal and foundational actions to be initiated or completed
by 2023.
The goal of Pillar 6, Natural Solutions, is to “increase carbon sequestration on the San Luis
Obispo Greenbelt and Urban Forest through compost application-based carbon farming
activities and tree planting.” These activities are projected to be ongoing through 2035.
Natural Solutions foundational action 2.1 – “Prepare the City’s first Urban Forest Master Plan by
2021 and plant and maintain 10,000 new trees by 2035” – reads as follows:
The City will prepare its first Urban Forest Master Plan that updates the existing tree inventory
and identifies future tree planting opportunities with climate-ready tree species, as well as
strategies for ongoing operations and maintenance. The Urban Forest Master Plan will also
include a feasibility study to propose and assess an ambitious tree planting campaign called 10
Tall: An Initiative to Plant 10,000 Trees in San Luis Obispo by 2035.
It is not presently known how close the planting of 10,000 new trees would bring the City to a
target of 25% canopy cover, or when exactly that might occur.
E. Conservation Guidelines for Open Space Lands (2002)
Vegetation Management Policy LV4, Native Trees:
Preserve all native trees when feasible.
Vegetation Management Policy LV5, Tree Planting:
Plant new native trees to increase benefits to wildlife where appropriate. Use fencing to exclude
livestock and damaging wildlife (e.g., deer) from newly planted areas.
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Fire Management Policy LV6, Vegetation Thinning:
Thin eucalyptus, pine and cypress plantations, shrub-land or woodland areas occurring along the
wildland/urban interface to create a less fire-prone condition.
Fire Management Policy LV8, Controlled Fires:
Use controlled burns for vegetation or pest management, as per prescribed burn plan prescribed
for the site. All affected residents will be notified prior to any prescribed burn.
Fire Management Policy LV9, Fire Safety:
Maintain adequate defensible spaces at the urban/open space interface, providing sufficient
space between structures and flammable vegetation within which the fire service can mount a
defense against fire.
Formulate fire preparedness/management plans for City open spaces. Employ firefighting
methods which have the least impact on the natural resources represented on the site, providing
the use of such methods do not put property or human life in danger.
F. Multi-Jurisdiction Local Hazard Mitigation Plan (2019) (Lead Agency: San Luis Obispo County)
City of San Luis Obispo Mitigation Action SL.17 – Flood:
Description/Background/Benefits: Develop and carry out environmentally sensitive flood
reduction programs.
Action Status: In progress. …review City owned property and property with drainage
easements covering private properties and conduct vegetation management/removal as
needed; …Assess and remove as necessary undesirable trees from creek system with
tree/landscape contractors.
City of San Luis Obispo Mitigation Action SL.22 – Wildfire, Drought:
Description/Background/Benefits: Support ongoing urban forest maintenance and tree trimming
programs, to include planting drought-resistant trees and plants.
Action Status: In progress. Urban Forest Services continues regular maintenance which
includes pruning and dead tree removal in City Streets, Parks and other City owned
properties.
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H. Downtown Concept Plan (2017) and Mission Plaza Concept Plan (2017)
Downtown Concept Plan, Implementation Actions 71-73:
71. Work with partners on exploring funding incentives for additional streetscape improvements,
such as adopting a tree or a planter (similar to the memorial bench and rack with plaque
program).
72. Maintain a healthy downtown street tree canopy; seek to ensure obstruction -free sidewalks
as well as proper tree health and growth capacity.
73. Include green infrastructure in public improvement projects whenever feasible.
Mission Plaza Concept Plan, Relevant Items:
15. Living Holiday Tree
20. Moon Tree Interpretive Exhibit
I. Presidential Executive Order on Strengthening the Nation’s Forests, Communities, and
Local Economies (2022)
On April 22, 2022, President Biden issued an Executive Order expanding US government efforts
to tackle the climate crisis, make our nation more resilient to extreme weather, and strengthen
local economies (The White House, 2022). The Executive Order is intended to:
• Safeguard mature and old-growth forests on federal lands, as part of a science-based
approach to reduce wildfire risk.
• Strengthen reforestation partnerships across the country to support local economies
and ensure we retain forest ecosystems and sustainable supplies of forest products for
years to come.
• Combat global deforestation to deliver on key COP26 commitments.
• Enlist nature to address the climate crisis with comprehensive efforts to deploy nature-
based solutions that reduce emissions and build resilience.
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VIII. New Urban Forestry Contracts (2021)
In 2021, the City awarded several new contracts as part of its effort to address deficiencies in its
urban forest program. The contracts were for maintenance, a street and park tree inventory,
and an organizational assessment report.
A. Maintenance
Davey Expert Tree Company and West Coast Arborists were contracted to provide maintenance
services for City street and park trees. These contracts were needed in order to address several
years’ worth of deferred maintenance including pruning and overall health evaluation.
B. Tree Inventory
The City awarded a contract for a new street and park tree inventory to West Coast Arborists, to
replace the previous, outdated inventory. Along with the recently initiated maintenance efforts,
the new inventory will provide updated information to inform future management planning,
including the writing of this Community Forest Plan.
C. Urban Forestry Organizational Assessment
Davey Resource Group (DRG) was commissioned to prepare an Urban Forestry Organizational
Assessment (OA) for the City Public Works Department. DRG reviewed the current Urban Forest
Services program, including structure and operations, background documents, and existing
policies. DRG also engaged key partners and community members and conducted an online
survey to gauge community awareness and support for the urban forest.
1. Findings
The OA reported that as of 2012, the City was estimated to contain 1,050 acres of tree canopy
for an overall canopy cover of 13.2%, with the highest canopy cover percentages in office and
residential areas (approximately 19% each) and the lowest in business parks, at 2.5% (Nessen,
2012). The nonprofit organization American Forests recommends 25% to 35% canopy cover for
dry western cities (Deeproot Green Infrastructure, 2022b).
The above estimates were derived from Light Detection and Ranging data (LIDAR [USDA Forest
Service Northern Research Station, 2011]) acquired from an aircraft and therefore pertain to all
trees within the city limits (i.e., including private and open space trees). However, it would not
be feasible for the City to obtain a full characterization (age classes, size classes, species
composition) of all of these trees through on-the-ground assessment due to presumed access
difficulties on private property. Thus, in the future the City may decide to use LIDAR or other
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remote sensing tools again in order to generate updated estimates of percent canopy cover by
land use type.
The DRG Organizational Assessment also evaluated the condition, age distribution, and species
composition of the City’s street and park trees. The Assessment found that 92% of these trees
are in “Good” condition or better (37%) or in “Fair” condition (55%). They exhibit a nearly ideal
age distribution of many young trees and fewer old trees. Finally, species composition was
found to be acceptable, with no species comprising more than 10% of the total (the most
numerous species, coast live oak, was at 10%).
In the past, the City used a tree inventory management system called ArborPro to inventory
trees in the public right-of-way and heritage trees on private property. In 2013-2014, this system
was integrated into a larger system called Cityworks. However, after 2014 the system was rarely
updated. The Organizational Assessment noted that the completion of a new tree inventory
housed in a comprehensive management system would strengthen the program in several ways.
The system would allow for multiple functions including tracking, recording data, mapping,
creating real-time workflows, analyzing work history, and sharing of data between Public Works
divisions, with other pertinent City staff, and externally with community partners (Davey
Resource Group, 2021).
2. Recommendations
The OA contained dozens of recommendations for consideration by the City in the following
categories:
• Urban Forest Resource
• Operations and Programs
• Urban Forest Partners
• Organizational Structure and Staffing
DRG also made several recommendations for future City planning efforts, including additional
exploration on the role of the Tree Committee, objective design standards, compensatory
planting requirements resulting from development, and expanded engagement with key
stakeholders and the community.
Many of the recommendations in the OA echoed comments made by CFP interviewees, and
there is significant overlap between DRG’s recommendations and those presented in this
document.
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IX. Key Findings of Stakeholder and Technical Expert Interviews
In addition to and complementary to DRG’s Organizational Assessment, the following key issues
were identified regarding San Luis Obispo’s urban forest program, based on stakeholder
interviews, literature review, and examination of other cities’ urban forest master plans:
A. Ensure adequate funding
B. Ensure adequate staffing
C. Complete program analysis and new tree inventory; accrue and analyze data
D. Strengthen maintenance practices and clear the backlog
E. Increase new plantings
F. Focus on sustainability
G. Address issues unique to downtown
H. Increase outreach to officials and the public
I. Address equity issues
A. Ensure Adequate Funding
Funding was one of the two most frequently identified high-priority issues among CFP
interviewees. Operating an effective urban forestry program is not inexpensive; one
professional tree maintenance company has estimated that it costs $250 for one newly planted
tree to make it to three years’ survival. In its Major City Goals for 2021-2023, the current City
Council expressed its support by recognizing the importance of renewed efforts to protect and
grow the City’s urban forest (City of San Luis Obispo, 2022a). Going forward, City residents must
stand firm and ensure that the Council maintains its commitment to adequate, long-term
funding if this program is to succeed and contribute meaningfully to the City’s efforts to address
climate change and improve quality of life.
Creative thinking is needed on the topic of funding for the urban forest program. One example
of this is the “Keys for Trees” program run by the San Luis Obispo Tourism and Business
Improvement District (TBID). The TBID elected to direct 1% of revenues from its 2021-22 budget
towards the City’s goal of planting 10,000 new trees by 2035 (City of San Luis Obispo, 2021;
Wilson, 2021). Other funding possibilities include local business sponsorships of the City’s tree
planting partners, and “gift tree” donations by individuals or businesses (City of San Luis Obispo,
2022b).
Several interviewees noted that there may be an opportunity to enhance program revenues by
modifying fee/permit structures and directing these monies into a new fund dedicated
specifically to the urban forestry program. Earmarking City revenues expressly for the urban
forest program would be useful for budgeting purposes, allowing for the detailed tracking of
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income and expenditures, and it would reduce interdepartmental competition for limited
general fund resources.
The City could also consider updating its tree removal application fee (currently, $157.17)
and/or penalties for unauthorized removals based on alternative valuation methods for the
tree(s) involved (valuation is currently based on methods established in the International Society
of Arboriculture’s Guide for Plant Appraisal). The dollar amount could be modified to be based
on either the value of the recoverable lumber or on the value of the ecosystem services
provided by the tree when it was alive. For instance, if a project’s tree removal replacement
ratio is 2:1, the replacement for one large tree would not necessarily be two smaller trees. It
would be whatever number of new trees was required to eventually provide twice the value of
the ecosystem services that were lost with the mature tree that was removed. Note that this
would require a financial commitment on the City’s part to purchase and use specialized
software (e.g., i-Tree Eco) to determine the values of said ecosystem services, or else to hire a
consultant to perform that type of analysis.
Alternatively, the City could consider basing tree removal fees and/or penalties on a percentage
of total tree diameter removed on a site, or allowing payment of an in-lieu fee instead. For
instance, the City of Paso Robles requires that 25% of the total diameter of trees removed be
replaced on site or a standard in-lieu fee be paid to fund planting on City property. As an
example, removal of a 12-inch diameter tree would require replacement of three inches of
diameter. At 1.5 inches minimum diameter for each replacement tree3, the result would be a
requirement for two new trees.
The City may also derive funding and/or savings by continuing to work with external entities
such as nonprofit organizations or other community groups, including through pursuing grant
opportunities. Opportunities like this can be important in the event of City-related budgetary
shortfalls. However, it is important to note that grant funding is temporary and therefore it is
essential to plan ahead for the time after the grant expires.
Without stable long-term funding streams, it will be very difficult to take the necessary steps to
protect and enhance San Luis Obispo’s urban forest into the future. Thus, regardless of the
details of any given revenue source, the City Council must maintain its commitment to adequate
funding if success is to be achieved.
B. Ensure Adequate Staffing
Aside from funding, staffing was the other issue almost unanimously identified as problematic
by interviewees familiar with the City’s Urban Forest Services division (UFS). Adequate staffing is
3 Slightly larger saplings are preferred over smaller trees because they are thought to be hardier and thus have a
better chance of establishment and survival (Roman et al., 2013).
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obviously dependent on adequate funding, but it has also been adversely affected in recent
years by retirements, injuries, and the effects of the Covid-19 pandemic. As of the beginning of
2022, UFS was down to one full-time employee and one part-time employee.
Interviewee insights on this situation revolved primarily around the need to determine what
level of staffing is proper, and in some cases, where City urban forestry personnel should reside
within the City’s organizational chart.
1. City Employees vs. Contractors
Interviewee opinions were mixed as to whether urban forestry personnel should be City
employees or contractors. The consensus was that while the program director and assistant
director(s) should be City employees, field crews could consist of either one. For in-office work,
an attractive option is to use interns or AmeriCorps members (including CivicSpark fellows).
The use of contractors was recommended in a City-commissioned audit evaluating the
management and performance of the City’s Public Works Department (Matrix Consulting Group,
April 2011). Using contractors offers certain benefits: the City is not responsible for buying and
maintaining expensive equipment; City staff workload may be reduced; the City can save money
over the course of time by avoiding staff injuries, liability issues, and payment of CalPERS
retirement benefits; and with fewer City staff it is less likely that retirements will disrupt
operations.
On the other hand, contractors require careful supervision and evaluation. One interviewee who
has worked extensively with tree care contractors noted that developing and maintaining trust
between a City and its contractors is crucial. Expectations regarding a contractor’s
responsibilities must be clearly spelled out. For example, a company may do excellent grid or
block pruning work but have little or no knowledge of long-term forest care concerns such as
disease, pests, and/or the likely effects of climate change.
One interviewee opined that it is best not to sign a maintenance contract that pays a contracted
company a per-tree flat rate regardless of amount of work needed; instead, they should be paid
only for the work they are actually directed to do.
2. Management
Regarding management, interviewee sentiment was that the City’s urban forest program
director needs to be a trained urban forester with a scientific background, planning and
management experience, and excellent interpersonal and outreach skills. This person should
espouse an holistic approach to urban forest management, be a strong advocate for the
program, and should be effective at working with elected officials, the City’s Tree Committee,
and other community leaders to achieve success. There were differing interviewee opinions as
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to what the title of the position should be, but feelings were unanimous that this person should
be a City employee. Some respondents felt that this person does not necessarily need to be a
certified arborist, although this opinion was not unanimous.
The director would oversee one to three assistant directors who are also City staff; at least one
of these should be a certified arborist. One interviewee suggested that assistant manager
leadership is needed in the areas of development review, code enforcement, and contractor
management. These positions, although working together, may not all be in the same
department. As of this writing, one decision has already been made: a new Contract
Maintenance Coordinator position will be created within the Public Works Department. In
addition, a job description is being created for a Citywide volunteer coordinator position, and
the Community Development Department may hire an arborist to conduct development review.
The director’s role would be office-based, interacting with City staff and other stakeholders as
well as overseeing program-level affairs. In contrast, the assistant director(s) would run the
department’s day-to-day operations, overseeing contractors and volunteers, and responding to
calls from residents as well as other situations in the field. The certified arborist would be an
appropriate choice to serve as City Council and staff liaison to the Tree Committee.
3. Volunteer Labor
The City already has a long history of working with local nonprofit organizations such as the
Rotary de Tolosa Club of San Luis Obispo and the Environmental Center of San Luis Obispo
(ECOSLO) to hold volunteer-based tree planting events on both public and private property.
Furthermore, the San Luis Obispo area contains an as-yet largely untapped volunteer base in the
form of Cal Poly and Cuesta College students, faculty, and staff. Volunteer tree planting and
maintenance events can not only provide large amounts of physical labor at relatively low cost
to the City and no cost to property owners, but volunteers bring with them enthusiasm and
energy, thus contributing to the community’s overall sense of purpose and pride.
The use of volunteers also comes with some caveats. Volunteer events are not entirely free, as
the City does incur some staff- and equipment-related costs. These include some degree of
training, as volunteers do not typically possess a high level of arboricultural expertise.
Furthermore, volunteers tend to be a more reliable resource for one-time or sporadically
recurring events as opposed to regular, long-term stewardship commitments. This can result in
inconsistency when volunteers or property owners agree to take on long-term tree care duties
but don’t follow through, which may eventually result in either additional burdens for UFS or in
tree decline/death. One CFP interviewee noted that it is common for newly planted trees to die
after a few years due to insufficient watering or other attention.
For this reason, ongoing outreach to property owners who request that volunteers plant a tree
in their yard can be crucial to the tree’s survival. In the case of new trees that have not been
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adopted by a property owner, the best option may be to have dedicated City staff or contractors
provide care for the first few years. Nonetheless, the interviewees largely agreed that volunteer
events are both a good source of labor and an important part of amplifying public interest and
buy-in.
4. Location within City Organization
Some CFP interviewees addressed the topic of where urban forestry belongs within the City’s
overall organization. Currently, Urban Forest Services is housed in the Public Works Department,
but as with the subject of hiring staffers vs. contractors, there is no single “right way.” Some
cities place urban forestry under a parks department or a natural resources department. One
interviewee, noting that there is often competition for funding both between and within
municipal government departments, suggested that urban forestry could be a new, standalone
City department.
One interviewee opined that public works is not the ideal location for the urban forestry
program, as the expertise of public works staff is in fixed infrastructure such as utilities and
hardscapes, while trees are a living, dynamic system (although, having said that, planting
locations such as tree wells, road medians, and sidewalk parkways are fixed infrastructure). It
was also stated that the City has seen high turnover of public works directors in recent years,
creating a perceived lack of continuity in management styles.
Regardless of the City’s ultimate decisions on the organizational placement of the urban forest
director and staff, it is certain that interdepartmental coordination and cooperation between
Public Works, Community Development, Parks, and the Office of Sustainability will be essential
in order for San Luis Obispo’s urban forest to continue to grow and thrive.
C. Complete Program Analysis and New Tree Inventory; Accrue and Analyze Data
In 2021, the City awarded several new contracts for tree maintenance, an updated inventory,
and an organizational assessment (see Section VIII, New Urban Forestry Contracts [2021]). As of
this writing (June 2022), drafts of the organizational assessment and inventory have been
completed and are under review.
The results of these efforts, in combination with data from other sources the City may choose to
obtain (e.g., LIDAR), will be critical in providing a foundation for setting urban forestry targets
and choosing metrics. Acquisition of current LIDAR data would also allow for a more
comprehensive assessment of total carbon stored and other characteristics across all trees
within the City – not just publicly owned trees, but those on private property as well.
Cities commonly use methods such as inventories and canopy cover analysis to guide urban
forest planning, management, and policy efforts but fail to conduct long-term monitoring or
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mortality assessments, resulting in incomplete information on the effectiveness of the program
(Roman, 2014). Therefore, San Luis Obispo should use the final selected metrics to monitor a
variety of forest conditions, including survival (or mortality), every year. The accumulated data
will allow for the annual assessment of year-over-year trends and progress toward overall goals.
This assessment, in turn, will be used to inform science-based best management practices that
will protect and strengthen the City’s urban forest, thereby promoting public health and
contentment.
The data gathered by the City may also be analyzed annually or every few years to determine
the dollar value of the benefits supplied by the urban forest. When publicized by the City, these
figures will serve as compelling evidence that protection and expansion of the urban forest is a
fiscally sound, responsible goal.
1. Targets
Currently identified targets include the following:
• Plant 10,000 new urban trees in San Luis Obispo by 2035 (City of San Luis Obispo,
2022b)
o Potential sub-target: plant a certain number of new trees per year
o Potential sub-target: plant a certain number of new trees per given geographic
area (hectare, square kilometer/mile, neighborhood, special-status zone [e.g.,
low-income], other)
• Reduce annual greenhouse gas (GHG) emissions by 1,490 metric tons of carbon dioxide
equivalent (MTCO2E) in 2035 (City of San Luis Obispo, 2022b)
Potential urban forest targets may include:
• Attain a specified percent tree canopy cover for the City as a whole, or by neighborhood
(includes privately owned trees)
• Attain 100% City tree well stocking
• Attain 100% replacement of other City trees that were previously removed (e.g., in
parks)
• Prune/mulch a specified number of trees per year
• Sequester a specified annual rate of MTCO2E per year
• Attain a specified total carbon storage amount (MTCO2E) in the City’s trees
• Designate primary and secondary species of City-owned trees for each City block, street
segment, and/or neighborhood
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• Produce neighborhood-level tree maps and make them publicly available online, similar
to the City of Santa Monica
• Attain a high percentage of “climate-ready” City-owned trees per geographic area.
These trees belong to species that are believed to be most resilient to the projected
effects of climate change in central California, both direct (increased heat, drought, air
pollution, extreme weather events) and indirect (increased attack by disease and pests).
• Achieve a certain dollar value(s) in specified ecosystem services.
2. Metrics
Potential urban forest metrics, measured by neighborhood and/or on a citywide basis, could
include the following examples. These metrics could be taken as one-time “snapshots” or, more
usefully, taken repeatedly over time in order to discern trends. Some of these would necessarily
be estimates:
• % tree well stocking
• % potential park tree stocking
• % survival of newly planted trees at x years (1, 3, 5, 10, 20, 30…)
• % canopy cover
• species composition/diversity
• annual carbon sequestration and total storage
• % public trees vs. total trees
• % private vs. public tree ownership
• impervious surface cover (this metric is negatively correlated with urban tree cover).
3. Data Analysis
The City may choose either to analyze its urban forest data in-house or to hire a vendor to do so.
A variety of private firms specialize in forest management analysis software and/or offer
consulting services. These companies commonly perform analytical studies for cities and other
agencies. One such firm that was mentioned as well-regarded by at least two CFP interviewees
is PlanIt Geo (PlanIt Geo, 2021).
Assuming that data collection will be ongoing and that the City’s inventory of street and park
trees (and perhaps the CFP itself) will be updated every few years, it is expected that analysis of
the urban forest data will lead to new insights and new initiatives over time. Evaluation of the
data may illuminate forest health- or growth-related trends that require action. For instance,
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use of certain species or certain types of planting locations may need to be changed, pruning
cycles may need adjustment, or program funding and staffing may undergo modification.
Because of the likelihood that adjustments will be needed over time, it will be important for the
City to retain flexibility by taking an adaptive management-based approach.
A Note on Canopy Cover: Percent canopy cover is a commonly used metric that measures the
percentage of ground covered by a vertical projection of the tree canopy (Egan, 2010). Currently
in the United States, there is a trend towards urban canopy cover increasing in multifamily
residential and office/business zones while decreasing in single-family residential (SFR) zones. In
California, this effect may be exacerbated by recent legislation promoting the construction of
accessory dwelling units (ADUs) in SFR zones as a strategy to address the State’s housing crisis.
The use of canopy cover as an urban forestry metric has come under some criticism in recent
years (Kenney et al., 2011), including from some CFP interviewees who believe it is not the most
useful measure for a City tree program. This is in part because it is difficult for a government
agency to significantly influence tree cover on a large (e.g., citywide) scale because most trees
are located on private property. Instead, CFP interviewees stated, it is more important to
quantify what the City’s existing trees are doing in terms of providing benefits, and to translate
that into dollar amounts that can be highlighted in outreach efforts.
D. Strengthen Maintenance Practices and Clear the Backlog
San Luis Obispo currently faces some of the same urban forestry concerns that have been
experienced by cities nationwide: declining age and species diversity, the effects of climate
change (drought-induced water stress, increased susceptibility to pest and disease attack,
damage from extreme weather events), and inadequate funding that affects staffing levels and
has resulted in years’ worth of deferred maintenance.
While planting new trees (see Section IX.E, Increase New Plantings) is an important and
necessary part of urban forest management as well as the City’s climate action strategy, it is at
least as important to properly care for existing trees to maximize their health, longevity, and
therefore, benefits provided. Some CFP interviewees noted that the funding and staffing issues
are of particular concern for this reason; if not given timely attention, many existing but
distressed trees that could otherwise be saved might die. Additionally, regardless of the cause of
a tree’s death, the City should consider its end-of-life use by planning for sustainable uses of the
lumber (see Section IX.F.2, Lifecycle Perspective).
Under current Public Works management practices, City-owned trees within San Luis Obispo are
split into nine pruning zones and intended to be pruned on a block-by-block basis (City of San
Luis Obispo, 2022g). Going forward, this maintenance will be the responsibility of contractor
crews; in 2021, the City signed a $150,000 pruning contract with Davey Tree Expert Company. A
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three-person crew will perform the pruning. The pruning contract should be helpful by reducing
both the maintenance backlog and workload on the current minimal City staff.
The concept of “pruning cycles” has commonly been used in urban forestry to budget for annual
maintenance, but several interviewees familiar with the topic felt this approach is less than ideal
due to large variations in the needs of tree species as well as individual trees.
It may instead be possible to have the contractor implement multiple, concurrent pruning
cycles. This would further reduce pressure on overtaxed City staff while allowing for more a
tailored approach to maintenance and thus forest health. However, if the decision is made to
stay with one overall pruning cycle, five years can be considered adequate.
At least one respondent also noted that it can be valuable for City staff to do annual ad hoc
“windshield surveys” of public trees in order to detect existing or incipient problems in a timely
manner.
E. Increase New Plantings
Agreement was unanimous among CFP interviewees that more planting of urban trees is
warranted in order to counteract ongoing urban tree loss and to ensure the presence of a future
urban forest that maximizes social, economic, and ecosystem benefits. The undesirable effects
of the trend towards loss of urban trees may be more pronounced in cities that have little
natural tree cover to begin with, like San Luis Obispo.
City streetscapes, parks, creek corridors, open space areas, and private property are all
appropriate locations in which to consider the planting of additional trees. In the past few years
the City has collaborated with local community groups, including the Rotary de Tolosa Club and
ECOSLO, to plant several hundred new trees in such locations. Building on these efforts, the
City’s 2020 Climate Action Plan for Community Recovery (CAP; City of San Luis Obispo, 2022b)
called for the rejuvenation and expansion of the City’s urban forest through the planting of
10,000 new trees by 2035. Subsequently, the City Council incorporated this proposal into the
City’s 2021-2023 Major City Goal for Climate Action, Open Space & Sustainable Transportation
(City of San Luis Obispo, 2022a).
To help get the process started, local stakeholders created the 10 Tall tree planting initiative. 10
Tall is a City campaign that is nested in the 2020 CAP, Pillar Six: Natural Solutions (City of San
Luis Obispo, 2022b). It is anticipated that the majority of the 10,000 trees proposed for planting
will be San Luis Obispo native species that will be planted in City open space areas and riparian
corridors. 10 Tall is expected to be a priority area of focus during the City’s CAP 2022 Update.
The City may also want to consider modifying its engineering standards to increase the number
of trees required in new development, including along sidewalks and in parking lots, as
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approved by a City arborist. For instance, the current requirement to plant one street tree for
every 35 linear feet of new sidewalk could be changed to one tree every 25 or 30 feet,
depending on the mature size typically attained by the species proposed for planting, or based
on a size class list. Small trees like crape myrtles could be planted at 25-foot spacing, while
larger trees like oaks or sycamores would still need 35-foot spacing. In parking lot areas,
standards could be modified to provide more space for trees to mature and thrive; instead of
planting only single trees in small islands, the City could consider requiring that groups of trees
be installed in larger islands to provide more cooling benefit.
Community engagement will also be an important part of the 10 Tall program. As of this writing
(June 2022), the group is working with computer science students at Cal Poly to create a website
where any community member – whether an individual, household, or organization – will be
able to register trees it has planted within the City limits. The database linked to the website will
be accessible to the City and its tree care partners to facilitate monitoring of progress toward
the 10,000 tree goal as well as the recording of urban forest metrics (e.g., diversity of species
planted or survival at various time points).
F. Focus on Sustainability
As awareness of global climate change has entered the general consciousness in recent years
and calls for action have become more urgent, the importance of urban forestry has begun to
receive more attention from the public. Tree planting has increasingly come to the fore as a
“low-hanging fruit” climate change solution (Mandel, 2021). Planting sites are numerous, trees
and volunteer labor are readily available, and there is nothing particularly complicated about
the procedure. The number of tree planting initiatives sponsored by government agencies,
corporations, and other entities has dramatically increased since the beginning of the 21st
century.
However, the issue is more complicated than it may seem. Putting trees in the ground is just one
small part of sustainable urban forest management. Furthermore, opportunities for missteps
abound in urban forestry – for instance, planting in the wrong location or planting species that
may not be resilient to the effects of climate change. Thus, comprehensive planning is needed in
order to avoid outcomes that diminish or negate the desired environmental, social, and
economic benefits that motivated planting in the first place.
1. Right Tree, Right Place
The “right tree, right place” concept ties together various aspects of sustainability that are
discussed on the next several pages.
A thriving, productive urban forest contains a mix of species and individual trees that are
appropriate for the physical location and environmental conditions in which they were planted.
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Urban trees, particularly street trees, are subjected to more challenging conditions and have
shorter lifespans than trees in more natural environments when compared to open
space/wildland trees (Smith et al., 2019). Average street tree lifespan has been estimated at 19
to 28 years (with a survival rate of new plantings ranging from 94.9 to 96.5%), while overall
average urban tree lifespan (including parks and residential trees) is considered to be 26 to 40
years (Roman and Scatena, 2011).
Thus, the determination of what constitutes “right tree, right place” should be made for each
individual combination of planting site and tree to maximize health, productivity, and longevity.
Failure to do this may result in reduced tree vigor, premature illness, and death, or premature
tree removal due to unwanted impacts on utilities or other infrastructure, not to mention
reduced or unrealized urban forest benefits.
Broadly speaking, sidewalk parkways and road medians are generally more suitable for smaller,
less messy trees, while larger species that drop more biomass but store more carbon and create
better wildlife habitat are more appropriate for use in parks, riparian corridors, or open space
areas. While urban foresters commonly favor large-growing tree species for maximization of
ecosystem services (USDA Forest Service, 2004), city residents tend to prefer smaller, fruiting or
flowering trees for their aesthetic benefits (Eisenman et al., 2021).
One example of a species that is not particularly well-suited for San Luis Obispo is the coast
redwood (Sequoia sempervirens). The city’s climate is very dissimilar to the fog-shrouded, damp
coastal environment where redwood grows naturally. While some local redwoods seem
reasonably healthy, many others are in poor condition, unable to thrive in our present climate
and presumably even less so in the future considering the predicted effects of climate change.
As another example, the huge, beautiful Indian laurel figs (Ficus microcarpa) in downtown San
Luis Obispo, while widely admired, have outgrown their environment. Cramped city sidewalks
are no longer an optimal location for these trees at their present size.
On the other hand palms, although they do not offer much in the way of cooling or carbon
sequestration, provide some degree of wildlife habitat and are appropriate for planting in areas
of limited space. Furthermore, palms are culturally important in southern California.
2. Lifecycle Perspective
Upon removal, urban trees have traditionally been considered to have little value and chipped,
burned, cut into firewood, or buried in a landfill (Nowak et al., 2019). However, these practices
either quickly or eventually allow the carbon stored in the wood to escape to the atmosphere.
Furthermore, a potentially useful job-producing and income-producing resource – to the tune of
46 million tons of wood per year, worth anywhere from $89 million to $786 million – is largely
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wasted. Even a year’s worth of leaf litter from the US is estimated to contain $551 million in
nutrients that could be turned into mulch or fertilizer (Nowak et al., 2019).
Thus, one way in which the CFP can contribute to sustainability is by promoting adoption of a
lifecycle perspective toward urban trees – that is, acknowledging that each tree serves one or
more distinct purposes from planting through removal and subsequent use of the lumber and
other organic debris. This concept requires a philosophical shift from “planting trees” to
“growing trees” (Mandel, 2021); that is, a change of focus to long-term maintenance practices
that encourage a lifetime of arboreal health. Failure to address these needs (i.e., neglect) often
results in poor tree health and low survival rates.
Interest in alternative uses of urban waste lumber has been rising for a number of years now.
The benefits of this approach include reduced wood waste in landfills, increased urban jobs,
reduced need for harvesting rural forests, and potentially avoided carbon emissions and
enhanced municipal forest management revenue (Nowak et al., 2019). The lumber can be used
in a wide variety of ways, including as feedstock for engineered woods, landscape mulch, soil
conditioner, animal bedding, compost additive, sewage sludge bulking medium, and boiler fuel
(CalRecycle, 2022c).
However, some CFP interviewees also expressed the desire to see waste lumber used in the
creation of boutique furniture, public art, or infrastructure such as fencing or benches, which
would store the carbon within the wood indefinitely and could be installed throughout the city
with educational signage around sustainability. Local company Pacific Coast Lumber was
featured in a 2016 news story using urban lumber to create just such products, building
handcrafted cabins, sheds, benches, tables, chairs, and flooring among other products from
dead and diseased Monterey pines that were removed from Cambria’s pine forest (Buffalo,
2016). In order for this idea to work long-term in a city setting, urban forest managers will need
to consider lumber quality in addition to the various other desired benefits from trees under
their care when choosing trees to plant.
In a related project, in 2020 the local nonprofit ECOSLO received a CAL FIRE Urban and
Community Forestry grant for a program called “Full Circle: A Sustainable Approach to Urban
Lumber in San Luis Obispo” (CAL FIRE, 2020). This multifaceted project would divert 600 urban
logs from the waste stream over three years, plant 240 new trees, and create a new college and
vocational curriculum, donating wood to and working with local schools to teach students about
the sustainable processing and use of urban wood. ECOSLO contracted with local business
Deadwood Revival Design for program implementation. As of this writing, the Full Circle
program is in progress.
Urban lumber can also be used in cogeneration, the creation of bioenergy (electricity, heat, fuel)
from waste biomass. Although some carbon dioxide is generated and escapes to the
atmosphere in this process, the net effect is reduced GHG emissions and air pollution (including
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methane) through the replacement of dirtier, fossil-fuel based equivalents. Finally, waste
biomass from tree removal can be used to create biochar, a charcoal-like material that when
added to soil can store carbon in the ground for thousands of years, while improving the soil’s
nutritional and moisture-holding capacity (Hawken, 2017, pp. 64-65).
The Hitachi Zosen-INOVA dry anaerobic digester near the San Luis Obispo airport reduces
greenhouse gas emissions by diverting green waste and food waste from the Cold Canyon
landfill and recycling them into compost, liquid fertilizer, and electricity (Hitachi Zosen Inova AG,
2021). However, the facility cannot process large woody debris; SLO County does not currently
have any facility that can do so.
3. Climate Readiness
Climate readiness refers to the resilience of an urban forest to environmental stressors resulting
from the effects of global climate change (McPherson et al., 2018). Climate change has been
predicted to inflict increasing heat, drought, wildfire, and extreme weather events on California
in the coming years and decades, while also increasing exposure to attack by current or
emerging insect pests and pathogens. Furthermore, these effects may be exacerbated in cities
due to the urban heat island effect, air and water pollution, poor soils, and accidental or
intentional damage (vandalism).
Lack of irrigation water may also become cause for concern. As with many other cities, San Luis
Obispo contains numerous examples of ornamental trees that originated in wetter climates and
require substantial irrigation in order to thrive. These varieties are not considered adaptable to
the projected, increasingly harsh environmental conditions accompanying climate change and
therefore will likely experience increasing decline and death in the coming years, whether
directly from climatic conditions or from property owners reducing or discontinuing irrigation
(on the other hand, water conservation measures and recycled water are still largely untapped
resources whose use may be expanded). Drought-weakened trees will also increasingly
comprise a public safety hazard, with associated financial costs. For all these reasons, research
to identify and test the resilience of potential new urban tree species is urgently needed to
protect the long-term stability of urban forests (McPherson and Berry, 2015).
In California, researchers with the University of California, UC Davis, and the USDA Forest
Service are conducting a study on this subject. The Climate Ready Trees project aims to identify
the suitability of underutilized but promising tree species for urban planting in the context of
climate change pressures (McPherson et al., 2018). Dozens of trees have been planted for
evaluation in the Sacramento area and throughout southern California. Although growth and
survival monitoring is ongoing, initial observations from southern California indicate that some
species native to hot, dry landscapes are performing better in inland locations than in coastal
locales, while others are tolerant of coastal conditions but require frequent pruning for optimal
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growth and health (McPherson et al., 2020). Overwatering is a stressor for some of these
species and can result in crown growth that outpaces root growth, with poor outcomes.
Cal Poly San Luis Obispo’s Urban Forest Ecosystem Institute (UFEI; Urban Forest Ecosystems
Institute, n.d. [a]), home of the SelecTree system, is also involved in the effort to find and
evaluate climate-ready urban trees.
4. Diversity
Diversity is a core ecological concept that refers to the variety and relative abundance of a
species (Magurran, 1988). High species diversity, age diversity, and geographic distribution are
believed to lead to greater population resilience because although decimating factors (e.g.,
pests and disease, natural disasters, exploitation by humans) may act upon specific portions of a
diverse population, a single event is unlikely to eliminate the entire population of that species.
In contrast, monocultures or other areas of limited diversity are theoretically at higher risk of
being eliminated by a single decimating event. High tree species diversity can also enhance
benefits including aesthetics and wildlife habitat.
Urban forests in the US typically have far higher species diversity than adjacent native forests or
woodlands (Robertson and Mason, 2016). In California, overall urban tree species diversity is
considered adequate, but 39 of 49 inventoried communities were identified as being over-
reliant on a single species of street tree (typically London plane, sweetgum [liquidambar],
Chinese pistache, velvet ash, or Callery pear) (McPherson et al., 2016). This is in part because
commercial tree growers naturally meet demand by focusing on varieties that are easiest to
grow and sell most readily to high-volume buyers. When one of these trees dies or is removed,
it may be wise to consider replacing it with a different, more appropriate species. One suggested
best practice for urban forestry is to aim for a forest composition of no more than 10% of any
single tree species, no more than 20% of species in any tree genus, and no more than 30% of
species in any tree family (Santamour, 2004).
San Luis Obispo does contain some individual trees of uncommon species that were planted
long ago but for which replacements from the same species are no longer available, contributing
further to concerns about declining species diversity in the city over time. City staff anticipates
that the 2021-2022 street and park tree inventory conducted by West Coast Arborists (under
review as of this writing) will be helpful for assessment of urban tree diversity in the city, even
though it will not include trees on private property.
5. Pests and Disease
With each passing decade, the number of non-native, invasive pests and diseases in California
increases through commercial activity or other means of transportation from distant areas.
When these organisms establish self-sustaining populations, the result can be tens or hundreds
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of millions of dollars in damage and mortality, whether to crops, wildlands, or urban plants and
trees. In urban forestry, the costs associated with managing pests, disease, and dead trees are
unavoidable; action must be taken due to public safety hazards such as falling trees and
increased wildfire risk.
San Luis Obispo County has been living with one such invasion since at least the early 1990s. The
disease pitch canker, caused by the fungus Fusarium circinatum, was inadvertently introduced to
California (Santa Cruz County) in 1986. This pathogen has caused enormous die-off of pines in
California, including the widely planted Monterey pine (Pinus radiata). The poor condition and
high fire hazard of Cambria’s native stand of Monterey pine, where pitch canker was first
detected in 1994, is in part due to this disease. Because pitch canker has also caused significant
morbidity and mortality in ornamental pines in San Luis Obispo, it is specifically called out in the
City General Plan’s Safety Element, Chapter 8: Hazardous Trees.
It is possible that this unfortunate situation could be repeated in other tree species in San Luis
Obispo County before long. Sudden oak death (SOD), caused by the fungus-like microbe
Phytophthora ramorum, is estimated to have killed over one million trees, mostly oaks and
tanoaks, in coastal California since its discovery in the mid-1990s (UC Riverside CISR, 2022). SOD
also infects dozens of other native plant and tree species, and it is currently documented in
southern Monterey County – just a few miles from the San Luis Obispo County line. Research
indicates that the strongest predictor of SOD is the presence of California bay laurel
(Umbellularia californica; California Oak Mortality Task Force, 2021) – a native tree that grows in
abundance in San Luis Obispo’s riparian and open space areas.
The invasive shot hole borers (ISHB), two closely related species of tiny wood-boring beetles
from Vietnam and Taiwan, were first detected in large numbers in southern California between
2012 and 2014. These beetles attack 58 tree species, killing the trees in two ways: by girdling
(tunneling through living tissues), and through the introduction of fungi of the genus Fusarium
which eventually clog the tree’s vascular tissues, preventing the movement of water and
nutrients. In 2017, ISHB was predicted to have the potential to kill 27 million trees in southern
California (Eskalen and Lynch, 2017). As of this writing, exactly one ISHB specimen has been
found in San Luis Obispo County, in 2016. The County Agricultural Commissioner’s Office is
conducting limited monitoring to watch for this pest.
In each of these cases and others of concern not discussed here (e.g., goldspotted oak borer –
Agrilus auroguttatus), widespread establishment of the pathogenic organism would be a serious
threat to anywhere from one to dozens of native and urban trees species in San Luis Obispo
County. For this reason, the CFP must address the City’s response to invasive species affecting
the City’s urban forest. In addition, some types of trees may themselves be considered invasive
species, e.g., tree of heaven (Ailanthus altissima), black locust (Robinia pseudoacacia), Peruvian
pepper (Schinus molle), Canary Island date palm (Phoenix canariensis), and certain Acacia and
Eucalyptus species.
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Prevention and monitoring are essential; the City must work with partners including San Luis
Obispo County, CalFire, Cal Poly, PG&E and others to keep up with the latest information and
best practices. As regards prevention, it was noted previously that one factor strengthening the
urban forest is species diversity. In reforesting the City’s open space and creek areas as part of
the 10 Tall campaign, it is natural to focus on planting San Luis Obispo’s native riparian tree
species (sycamores, cottonwoods, willows, maples). However, consideration must be given to
the susceptibility of these species to each invasive pest of concern, to the extent possible.
For instance, the experience with ISHB in southern California has shown that the riparian tree
species listed above seem to be these insects’ most highly preferred hosts. Thus, in light of the
potential threat to San Luis Obispo County, it may be prudent to consider reducing the
proportions of those species planted in the City’s open spaces and creeks, replacing them with
less-affected ISHB host species such as coast live oak (Quercus agrifolia), or with species like
California black walnut (Juglans californica) that have not been identified as hosts of ISHB.
Upon detection of a novel pest, a rapid, IPM (integrated pest management)-based response will
be required. The basic steps include quarantine, cultural practices including tree removal where
indicated, and use of insecticides and biocontrols (as available and deemed necessary). Thus,
the City should have funds available to respond to fast-breaking situations using an “early
detection, rapid response” mantra.
6. Municipal Tree Lists
A municipal tree list is a compilation of city-approved tree varieties that is maintained by some,
though not all, cities. Examples of factors that may go into a municipal tree list include whether
a given species has a propensity for disrupting sidewalks and utilities, is a nuisance due to
dropping copious biomass or releasing excessive pollen, is compatible with local climate and
soils, and is aesthetically suitable for its intended location (City of Lodi, no date). In some cases,
these lists have been perceived as limiting and drawn complaints from the public. Given the
already alarming effects of climate change, Californian cities with tree lists (including San Luis
Obispo) will need to make some decisions around updating their lists for the future.
The City’s current Street Trees Master List (City of San Luis Obispo, 2018) contains 68 species or
cultivars that are approved for planting in the City. The San Luis Obispo City Arborist has the
authority to approve planting of additional, non-listed species on a case-by-case basis. The City
Tree Committee may work with City staff and partners to update the tree list as often as once a
year in order to remove less-than-desirable trees (for example, those that require excessive
amounts of water) and replace them with climate-ready varieties. On the other hand, the City
may also consider other options including eliminating the tree list altogether (some cities do not
have one), creating multiple lists (one for streets, one for parks, one for open space, etc.), or
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adopting a list of non-approved trees – i.e., banning the most problematic species while not
regulating other species.
Ideally, decisions about the Street Trees Master List will be informed by the latest research on
climate-resilient trees, such as that occurring at UFEI. However, even when or if such species are
found, the desired trees may not be commercially available. CFP interviewees identified two
California-based growers, Devil Mountain Nursery and San Marcos Growers, who have
expressed interest in experimenting with growing new species of climate-ready trees for their
customers.
Thus, identification of what constitutes “right tree, right place” in 21st century San Luis Obispo is
work in progress. Regardless, it can no longer be considered appropriate to simply choose urban
trees based on cost alone or on whatever is available in the greatest quantities, without taking
into account resilience to changing environmental factors.
7. Tree Committee
The City’s Tree Committee is an advisory body that makes recommendations to the City Council,
staff, and Planning Commission on tree policies and regulations (City of San Luis Obispo, 2022f).
The Tree Committee consists of one representative of the City Parks and Recreation
Commission, one representative of the Architectural Review Commission, and five members
from the general public – one of whom must be a horticultural expert.
The Tree Committee reviews development proposals, hears appeals of tree removal applications
that were denied by the City Arborist, and makes recommendations on heritage tree and
“significant tree” designations as defined in the City Municipal Code and the General Plan
Conservation and Open Space Element. As noted previously, the Tree Committee may also assist
in updating the Street Trees Master List in cooperation with City staff and partners.
There are currently some uncertainties surrounding the Tree Committee. The following
points/opinions regarding the Tree Committee were raised in the Davey Urban Forestry
Organizational Assessment (Davey Resource Group, 2021, p. 58):
• The roles, responsibilities, and authority of the Tree Committee are ambiguous
• The Tree Committee is housed within the Public Works Department yet spends the
majority of deliberations on topics relating to private trees
• The community is undergoing a significant amount of infill development, partially
related to an increased demand for housing, commercial sites, and the recent state
Housing Mandate. Increasingly, the Tree Committee is being asked to review these
development plans
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• (In some cases,) The Tree Committee is the last governing body to review large
development proposals. In most situations, by the time these projects are presented to
the Tree Committee, they have already been approved and the Tree Committee’s
recommendations may or may not be taken into consideration
• There is no requirement for City staff involved with the proposal process to report back
so that the Tree Committee knows whether or not their recommendations are being
implemented
• Currently, neither the Tree Committee nor the City Arborist serve as a liaison/support
for the Architectural Review Commission, yet this Commission reviews projects that
involve consideration for tree preservation and removal permits
• The Tree Committee has a limited advocacy role for urban forestry budgeting through
an annual report to the City Council that includes desired improvements.
Furthermore, CFP interviewees offered the following observations/opinions about the Tree
Committee:
• Members of the Tree Committee want decision-making authority regarding
development proposals, but there is no consensus on the topic among interested
parties
• Cases have arisen in which the Tree Committee requested more than one hearing on a
development-related tree issue, leading to conflict because of California Permit
Streamlining Act requirements. This piece of legislation limits hearings on development
projects to a total of five for any given issue, and City staff believe that two of those
slots should always be reserved for City Council deliberations. This may not be possible
if the Tree Committee, Planning Commission, or other applicable advisory bodies hold
multiple hearings on a project
• Some CFP commenters felt that the City has a surplus of advisory bodies as it is, and that
the Tree Committee could be replaced by one City staffer plus one member of the public
who has expertise in arboriculture.
If the City was to move forward with replacing or modifying the duties of the Tree Committee, it
would be appropriate to consider whether (and if so, how) this would affect the ability of
interested members of the public to observe and provide input into tree-related City actions.
8. Soil and Infiltration Enhancement
Street trees typically exist in harsh urban environments with poor soil conditions. Urbanization
results in the conversion of natural land cover to impervious surfaces, changing natural drainage
characteristics and inhibiting infiltration of water, gases, and nutrients into the soil.
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Furthermore, urban trees commonly suffer from other challenging growth conditions including
lack of growing space, soil compaction, high salinity, and/or unfavorable pH, and they can be
damaged by pollution and physical interference from infrastructure. These conditions can stunt
trees and plants, significantly limiting their health and lifespan (Lawrence et al., 2012).
Compost Procurement under SB 1383: California’s Short-Lived Climate Pollutant Reduction law
(SB 1383) establishes methane reduction targets through diversion of organic waste that would
otherwise go into the landfill (CalRecycle, 2022a). The law requires recycling of food waste and
addresses hunger through the recovery of edible food from the waste stream. Under SB 1383,
counties and cities are required to procure a certain tonnage of compost each year for their own
use or for donation to the community. The City of San Luis Obispo’s compost procurement
target for 2022 through 2026 is 3,685 tons per year (CalRecycle, 2022b). Because this amount of
compost exceeds current known uses for it, a potential exists for the surplus to be used in City
tree planting and care, as well as in application to City open space rangeland (carbon farming).
Soil- and Infiltration-Enhancing Technologies: In recent years a variety of new soil-enhancement
technologies have been developed for the dual applications of stormwater infiltration/water
quality improvement and urban tree growth enhancement. These products are designed to
improve infiltration and remove suspended solids and other soluble pollutants while facilitating
the growth of larger trees than would otherwise be possible in confined urban settings, without
damaging sidewalks, streets, or utilities.
One of these solutions is engineered soils, which consist of specific, proprietary blends of gravel,
sand, silt, clay, and organic matter. By improving soil structure and chemistry, engineered soils
can enhance tree and landscaping root growth and therefore overall health. This can be
especially important in physically constrained planting sites such as small tree wells or planters.
However, this type of product must be used with carefully chosen tree species due to its
sometimes low nutrient content.
One CFP interviewee regarded engineered soils as the most practical and cost-effective soil
technology for a city to use, although they are not inexpensive. For example, approximately 11
yd3 of Cornell engineered soil (CU-Structural Soil®; Denig, 2015) is recommended for the
planting of a single street tree. At a typical price of $40 per yd3 (range = ~$35 to $75/yd3), this
comes out to $440 per tree.
Another soil-enhancing product is soil cells such as the Silva Cell (Deeproot Green Infrastructure,
2022a). These “modular suspended pavement systems” consist of crate-like structures, posts,
panels, geotextile fabric, and mesh that are assembled in excavated trenches where trees will be
planted and backfilled with planting soil.
Soil cells work well (they are the “gold standard” according to one interviewee), although their
cost – $14 to $18/ft3 installed, or approximately 10 times more expensive than the Cornell soil
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referenced above – makes them likely to be cost-prohibitive for most public planting situations.
On the other hand, their proven ability to enhance long-term tree growth and health means that
these products might be suited for limited use in challenging, streetside planting areas such as
along Monterey, Higuera, and Marsh Streets in San Luis Obispo. Private commercial or
residential development can also benefit from the use of soil cells; the City might consider
requiring soil cell installation as a condition of new development under some circumstances.
Additional products in the same vein that were mentioned by CFP interviewees included water-
absorbing polymers (hydrogels) added to the soil; rubber sidewalks (Terrecon, Inc., 2014), which
received mixed reviews; suspended sidewalks; and pervious (permeable) concrete or other
hardscape surfaces. A study conducted in Australia found that permeable pavement increased
soil moisture in drier sandy soil but decreased moisture in wetter clay soils, with the effect on
soil moisture fluctuating depending on both soil type and depth of the aggregate base layer
under the pavers (Mullaney, 2015). Under some of the experimental conditions, tree diameter
growth was up to 65% greater with permeable pavement than with the control (regular asphalt
pavement).
9. Safety
The San Luis Obispo City General Plan’s Safety Element (last revision 12/9/2014) identifies fire,
flooding, and hazardous trees, among other issues, as threats to public safety. The proximity of
urban development to natural (non-urbanized), topographically varied landscapes in
combination with the effects of climate change increases the potential for injury, death, and
property destruction due to natural disasters. As of this writing (June 2022), the Safety Element
is being updated.
The City of San Luis Obispo was a participant in the 2019 Multi-Jurisdiction Local Hazard
Mitigation Plan (LHMP) spearheaded by San Luis Obispo County (County of San Luis Obispo,
2019). The LHMP relies on risk and vulnerability assessments to craft goals, objectives, and
actions that provide “practical, meaningful, attainable and cost-effective mitigation solutions to
reduce vulnerability to the identified hazards,” thereby reducing human and financial losses. The
LHMP evaluates 16 potential hazards facing the county and its communities, identifying tree
mortality resulting from drought stress and pathogen attack as a significant hazard. Other tree-
related hazards include adverse weather and wildfire.
Wildland Fire: Homes and other buildings throughout the city are located in close proximity to,
or interspersed with, hillslopes containing stands of native trees and brush. This zone of mixed
land cover is known as the wildland-urban interface (WUI). The past two decades of increasingly
severe and uncontrollable fires in the western US have shown that the physical effects of
climate change on wildfire behavior (e.g., higher wind speeds, lower relative humidity and fuel
moisture, potential for large areas of drought- or pest/disease-killed vegetation) have now, in
many instances, intensified beyond the point at which fire suppression efforts are effective let
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alone safe for fire crews. However, this reality does not obviate the need for the City to continue
to strengthen its defensible space regulations and conduct fuel reduction treatments in the
WUI; thus, urban forest planning must assess wildfire vulnerability.
Flooding: Much of the city’s urban development is located near the city’s creeks, within or in
proximity to 100-year and 500-year flood zones. Flooding can be caused by rocks, trees, and
other debris falling into waterways and blocking culverts and creek channels. This effect may be
exacerbated after a wildfire, particularly in steeper watershed areas, as the lack of vegetation
and eventual decay of fire-killed roots mean that the soil is more vulnerable to erosion. Other
effects of flooding can include inundation of structures, impact damage from flood flow and
debris, crop destruction, and release of hazardous materials including untreated sewage.
Hazardous Trees: Trees that threaten public safety may result from a variety of situations
including poor environmental conditions or maintenance, pests and disease, or routine
senescence and death. The City must continue to identify and monitor hazard zones, evaluate
the potential for emergencies, and plan for site access and other responses.
10. Water Conservation
Given the increasing unreliability of winter rains in central California, water use is necessarily an
important part of the conversation around San Luis Obispo’s urban forest. New policies,
practices, and technologies – as well as increased reliance on existing ones – are needed going
forward.
Substantial and as yet unrealized water savings are possible in California through more stringent
water conservation, recycling, and stormwater capture efforts (Gleick et al., 2014). The City of
San Luis Obispo currently uses recycled water (indicated by purple signs and piping) for various
non-potable uses including irrigation of street and park trees (City of San Luis Obispo, 2022e).
While a detailed examination of water-saving methods is outside the scope of this plan,
irrigation practices bear brief discussion here.
The City currently uses sprinkler, drip, and manual irrigation to water public landscaping,
including turf and trees. In many parks and some street tree locations, as well as in new
development, the City is using or requiring use of recycled water. Minimization of turf and
conversion of sprinkler irrigation to drip should be a high priority for the City. Newly planted
trees planted in streetscapes, medians, parks, and other locations in the public right-of-way can
be located so as to take advantage of existing irrigation, but in some cases the City may choose
to install temporary or permanent drip irrigation to serve new plantings. If the City decides to
try any of the technologies described in Section IX.F.8, Soil and Infiltration Enhancement, drip
irrigation could be incorporated into the design.
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Having said all this, however, the City may achieve the same desired result (healthy, well-
watered young trees) by using a time-honored, water-wise irrigation method – placement of a
small, porous reservoir (“olla”) in the ground near each tree. These may be ceramic pots, or
even perforated plastic jugs. The neck of the olla extends above the ground surface for quick,
easy filling with water. Through soil moisture tension, the reservoir slowly releases water into
the soil when the ground is dry but retains water when the ground is wet. Water loss from
runoff and evaporation is minimal to none. After the tree has established, the olla can be
removed and used elsewhere.
G. Address Issues Unique to Downtown
Downtown San Luis Obispo is a “special” place that is “the heart of (the) community” (City of
San Luis Obispo, September 2017). Special events held in Mission Plaza and City parks, the
weekly Downtown Farmer’s Market, and everyday shopping, dining, and entertainment attract
many thousands of people year-round. For decades now, downtown’s lush tree canopy has
been an important part of the ambience that drives and nurtures such activities.
1. Downtown Concept Plan and Mission Plaza Concept Plan
By 2014, it was clear that American cities’ central business districts were suffering from the dual
onslaughts of suburban big-box retail centers and expanding online commerce. That year, San
Luis Obispo City leaders, staff, and residents felt strongly enough about protecting downtown
San Luis Obispo’s vitality and setting forth a vision for this space that both the Downtown
Concept Plan (DCP) and the Mission Plaza Concept Plan (MPCP) were updated following the
City’s General Plan Land Use Element update.
The DCP (2017) is intended to guide both public and private actions and investment in
downtown over the next 25 years, while the MPCP (2017) takes a close look at the plaza’s
condition, uses and policies, as well as impacts on neighboring properties and the San Luis
Obispo Creek corridor, opportunities for plaza expansion, and more.
The DCP specifically recognizes downtown’s urban forest in its Implementation Actions:
71. Work with partners on exploring funding incentives for additional streetscape improvements,
such as adopting a tree or a planter (similar to the memorial bench and rack with plaque
program).
72. Maintain a healthy downtown street tree canopy; seek to ensure obstruction -free sidewalks
as well as proper tree health and growth capacity.
73. Include green infrastructure in public improvement projects whenever feasible.
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Public feedback received during DCP meetings and workshops mooted the possibility of
establishing a “tree conservation corps” focused on tree preservation, expressed support for a
thriving tree canopy in general, and called for the annual evaluation and, if needed, replacement
of tree grates to ensure both pedestrian safety and tree health.
The MPCP highlights two trees of interest that could be publicized, for instance, by being
highlighted as part of a walking tour of downtown:
15. Living Holiday Tree
20. Moon Tree Interpretive Exhibit
2. Downtown’s Big Trees
Downtown San Luis Obispo would be unrecognizable to most locals without its big, beautiful
trees – notably including its iconic, roughly 60-year old Indian laurel figs (Ficus microcarpa).
These enormous evergreen trees were planted widely across urban California during a
beautification craze in the 1960s, based on their reputation as hardy “miracle trees” that could
withstand heat, drought, air pollution, and anything else a city could throw at them (Gordon,
1996).
These trees dominate the central business district in San Luis Obispo and many other cities in
California, contributing tremendously to aesthetics and sense of walkability. Their large, shady
canopies confer a pleasing “sense of place” that encourages spending time outdoors, whether
alone or in social gatherings, and increases contentment. The presence of these trees raises
property values and drives increased retail business traffic.
However, the same trees drop leaves, twigs, and fruit on pedestrian walkways; attract birds and
insects that can cause distress by entering businesses; block views and street signs; invade
sewer lines; and, crucially, incur ongoing taxpayer expense through their need for expensive
pruning and – even worse – expose cities to liability from falls caused by their upheaval of
sidewalks.
Furthermore, according to Cal Poly’s SelecTree website, Ficus microcarpa’s branch strength is
“medium weak,” they are a potential human health irritant due to the allergens and latex-
containing sap they produce, and they are not “powerline friendly” (SelecTree/UFEI, 1995-
2022).
By the mid-1990s, cities throughout California had either stopped planting Ficus microcarpa for
these reasons, or were actively tearing them out and replacing them with palms, often to the
consternation of tree lovers (Gordon, 1996). Some southern California cities, reluctant to cut
down these popular features of their downtowns, have opted to play the waiting game by
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performing root trimming, installing underground root barriers, and replacing sidewalks with
stone pavers around the trees – but the overall feeling on the part of arboricultural
professionals seems to be that this is a case of “wrong tree, wrong place.” Stakeholders
interviewed for the CFP mostly echoed this sentiment; there is a sense that as impressive and
enjoyable as these trees are, they have gotten too big for their surroundings.
As the number of Ficus and other large, 1960s-era trees in downtown San Luis Obispo slowly
dwindles through attrition, a replacement program based on planned rotation and “right tree,
right place” principles is likely. The plan is for a regular 20- to 30-year replacement cycle to be
put in place – some of the same species, including Ficus macrocarpa, may be replanted, but they
will not be allowed to again attain such enormous size in cramped sidewalk spaces. In future
decades, the vision for downtown SLO is that it will have a more diverse, mixed-age and mixed-
species tree palette containing a preponderance of species that, while still beautiful and
inspiring, do not have the potential to grow as large as the current specimens and cause the
aforementioned problems.
H. Increase Outreach to Officials and the Public
Several CFP interviewees stressed the importance of using outreach to build support for
initiatives that are intended to improve quality of life for City residents and visitors. Outreach is
essential because although research has found that overall public support for tree planting is
high, trees also have downsides. They can be messy, damage sidewalks and underground
utilities, comprise a safety hazard by dropping limbs or falling, attract insects, trigger allergies
with their pollen, block views, and be expensive to water and maintain (Conway and Bang, 2014;
Roman et al., 2020; Ziska et al., 2019). In addition, some tree species emit high levels of volatile
organic compounds (VOCs) that may contribute to the formation of ground-level ozone when
combined with human-generated pollutants (Churkina et al., 2017).4
Furthermore, many urban forest benefits are intangible and therefore not obvious and/or
meaningful to the general public; residential planting and removal of trees is based far more on
personal preferences such as aesthetics or maintenance concerns than on consideration of tree-
related ecosystem services (Conway, 2016). In general, it can be assumed that tree-based
information highlighting benefits that are more inherently obvious to the general public (e.g.,
landscape beautification, cooling and reduced energy bills, wildlife habitat) should have a
greater impact on driving support for the urban forest than would information requiring more
specialized knowledge, for instance regarding ecosystem services like air pollution removal or
reduction of flooding and erosion. However, given that the dollar value of environmental
services provided to a city by urban trees can easily be in the millions of dollars (in costs
4 Having said all that, many of these undesirable effects can be minimized through planning and regular
maintenance.
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avoided) annually, the City still might consider broadly publicizing ecosystem services as a
reason for continued support and growth of the taxpayer-funded urban forest program.
The City and its partners can enhance public buy-in to urban forestry efforts by continuing with
existing outreach programs, creating new ones, and by planning for and hosting special events.
One “low-hanging fruit” example would be to maintain the City’s existing Tree City USA
designation with the Arbor Day Foundation. As of this writing, San Luis Obispo has been a Tree
City USA participant for 38 years. The participation requirements include maintaining a tree
board or department, having a community tree ordinance, spending at least $2 per capita on
urban forestry, and celebrating Arbor Day (Arbor Day Foundation, 2022). The City has also been
the recipient of two Gold Leaf Awards from the International Society of Arboriculture (ISA).
Many other outreach opportunities were identified by CFP interviewees; please see Section XI.H,
Recommendations (Outreach).
I. Address Equity Issues
It is well documented that green infrastructure like urban forest cover and the associated
benefits are not equitably distributed in the US (Heynen et al., 2006; Landry and Chakraborty,
2009). Urban neighborhoods that were targeted for systematic disinvestment in the past (i.e.,
redlining) commonly lack adequate tree cover and other landscaping (Locke et al., 2020), which
deprives residents of access to tree-related benefits and exacerbates the urban heat island
effect, resulting in temperatures that can be significantly higher than in wealthier, tree-lined
areas in the same city (Wilson, 2020). This issue takes on even more importance in the context
of increasingly severe climate change effects (e.g., extreme heat, drought, wildfire, flooding).
The cumulative result is poorer public health and safety outcomes for the residents of these
neighborhoods, leading to the question, “How can a city ensure that environmental, social, and
economic benefits provided by the urban forest are equally distributed across all residents and
neighborhoods, both now and in the future?”
In San Luis Obispo, Diversity, Equity, and Inclusion (DEI) is both a Major City Goal in the 2021-
2023 Financial Plan and an important component of the 2020 Climate Action Plan for
Community Recovery. Davey Resource Group (DRG) addressed the topic of equity in their Urban
Forestry Organizational Assessment for the City Public Works Department (Davey Resource
Group, 2021). The Organizational Assessment states that while maintenance of trees in the
public right-of-way is equally distributed across the entire city and public parks are located
throughout the City, there are generally more opportunities for tree planting in newer
neighborhoods than in older ones. However, there is considerable uncertainty around this topic.
Among residents who responded to the urban forest poll conducted by Davey as part of the
Organizational Assessment, 63% of respondents were unsure whether urban forest benefits are
equally accessible to all; 20% said they are not.
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The DRG Organizational Assessment included the following recommendations regarding equity:
• Conduct an assessment to explore the distribution of public tree canopy and associated
benefits by neighborhood, census tract, and/or other geographic metrics
• Coordinate with the City’s Diversity, Equity, and Inclusion Task Force to identify gaps in
equity as regards urban forest access and benefits
• Develop equity strategies around the urban forest.
The nonprofit organization American Forests maintains an online data tool called Tree Equity
Score that estimates the equitability of tree canopy distribution in a city based on tree canopy
cover, climate, and demographic and socioeconomic data (American Forests, 2022). The result is
a score (0 = lowest, 100 = highest) that is calculated at the neighborhood (Census block group)
level and aggregated to the municipal level.
San Luis Obispo has an overall Tree Equity Score of 74 out of 100 (Treeequityscore.org, 2022).
The two highest scoring block groups are located between Broad Street and Santa Rosa Street,
south of Foothill Boulevard and north of US 101 (score = 94; canopy cover = 27%), and an area
mostly south of Foothill Boulevard including Ramona Drive and La Entrada Avenue (score = 91;
canopy cover = 21%). The two lowest scoring block groups are an area around S. Higuera Street
that includes Elks Lane, Bridge Street, and Fontana Avenue (score = 55; canopy cover = 9%) and
the area immediately to the south of that but north of Tank Farm Road (score = 46; canopy
cover = 7%). The Cal Poly campus, although not within the city limits, also earned a low score, 49
(canopy cover = 12%).
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X. Goals
Goals can be thought of as a high-level “road map” providing a framework for prioritizing
proposed actions and evaluating the success of one’s efforts. The following CFP goals are
proposals that were written by the author based on the stakeholder interviews, academic
literature review, and review of other cities’ urban forest management plans conducted for this
project. The topics addressed by these goals include forest health and expansion, funding and
staffing, collaboration/cooperation, climate resilience, outreach to the public, and
equity/justice.
• Maintain and enhance San Luis Obispo’s urban forest in order to maximize
environmental, social, and economic benefits for all, while minimizing undesirable
conditions
• Work to ensure adequate, sustained funding and staffing in order to implement the
City’s identified urban forest priorities
• Emphasize the planting and care of climate-ready trees in locations where they will have
the greatest chances of success in environmental conditions that are rapidly becoming
more challenging (i.e., “right tree, right place”)
• Foster a spirit of collaboration between and within City departments that are involved in
urban forest management, as well as between the City and other local stakeholders
(e.g., community groups, nonprofit organizations, utilities, other cities, Cal Poly, other
State agencies)
• Educate and seek the involvement of City residents and visitors, including historically
marginalized groups, in order to obtain their buy-in and support for a thriving urban
forest.
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XI. Recommendations
As with the CFP goals in Section X, the recommendations presented here are based on the
research conducted for this project, but at a much finer-grained level. The recommendations are
split into nine sections that match the format of Section IX, Findings of Stakeholder and
Technical Expert Interviews. As of this writing, these recommendations have been through
several iterations. It is the author’s intention that they will continue to be refined until they, and
the entire CFP, are in a form acceptable for presentation to the San Luis Obispo City Council.
A. Funding
• Develop a sustainable funding plan that looks further into the future than just the
current two-year budget cycle
• Continue to seek out creative new sources of funding for the urban forest program,
possibly including grants, new tax revenue sources (e.g., a parcel tax), general obligation
bonds, an assessment district, sponsorships, donations
• Modify fee/permit structures and direct additional revenues into an urban forest-
specific fund that allows for detailed tracking of costs and available funds to facilitate
the assessment of program effectiveness and inform future budget discussions
• Consider basing tree removal fees (and replacement requirements) on the value of
individual trees removed or on alternative methods (see Section IX.A, Ensure Adequate
Funding)
• Consider hiring an economic consultant to conduct an urban forest financing study.
B. Staffing
• Continue to emphasize to elected officials the need for adequate staffing, which follows
from adequate funding
• Determine the actual level of staffing needed, desired proportion of City staff to
contractor personnel, and location of City staff within the City’s organizational chart
• Create a new internal, interdepartmental urban forest working group along the lines of
the “Green Team,” or create one as a subset of the existing Green Team
• Ensure that the City’s new urban forest program director is a qualified urban forester (or
has a similar background) who is experienced at working with elected officials, advisory
bodies, and the public
• Ensure that at least one of the program director’s assistant managers is a certified
arborist who may serve as City liaison to the Tree Committee
• Consider hiring the following new City staff positions:
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o Development review arborist
o Volunteer coordinator
o For temporary office help, consider AmeriCorps and/or CivicSpark hires
• Continue to cultivate relationships with the City’s external partners, who bring
substantial value to the urban forest program through the provision of professional
knowledge and/or volunteer labor
• Consider approaching Cal Poly and/or Cuesta College to create a new student urban
forest steward program.
C. Complete Program Analysis and New Tree Inventory; Accrue and Analyze Data
• Consider augmenting the 2022 West Coast Arborists tree inventory data with the
acquisition of current LIDAR data, which would allow for more in-depth analysis of the
City’s urban forest – in particular, trees on private property, which presumably account
for the majority of trees within the City limits (possibly excluding open space areas)
• Identify desired urban forest targets and a science-based, feasible set of metrics for
long-term data collection
• Support the creation and public use of a website for the 10 Tall tree planting initiative
• Consider contracting with an urban forestry consultant to evaluate progress towards
targets and to quantify and place dollar values on the ecosystem services provided by
City trees, e.g., using a software package such as i-Tree Eco
• Provide the results to elected officials and the public in annual reports
• Consider conducting additional public surveys beyond that carried out in 2021 by Davey
Resource Group for their Organizational Assessment
• Plan to repeat the City tree inventory and subsequently update the CFP every five or 10
years. Updating the inventory will facilitate assessment of progress towards
targets/goals, illuminate trends in forest growth and health, and inform any proposed
changes in management practices, all of which can then be reported in the updated CFP.
D. Strengthen Maintenance Practices and Clear the Backlog
• Place the highest possible priority on catching up on deferred maintenance so as to
maximize urban forest growth and benefits while limiting preventable tree decline and
death
• Continue to work with CalFire and other City partners to identify and reduce or mitigate
wildland fire hazards, including threats to wildland-urban interface (WUI)
neighborhoods, as described in the Chapter 3 of the City General Plan Safety Element
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• Continue to identify and proactively respond to hazardous tree situations on public and
private property, as described in the Chapter 8 of the City General Plan Safety Element
• Implement ad hoc, proactive “windshield surveys” by City staff each year to identify
existing or incipient problems while they are still relatively minor and easily addressed
• Consider having new pruning contractors Davey Tree Expert Company and West Coast
Arborists implement multiple, concurrent pruning cycles in order to reduce workload on
City staff and provide a tailored approach that may better promote tree health
• Create a street tree replacement plan that requires timely replacement of
dead/removed trees and provides recommended tree species, rootstocks, and rotation
cycles in order to proactively address the recurring issue of tree-related sidewalk,
foundation, and underground utility damage
o Specifically, address plans for the intended replacement of large downtown
street trees, as these are the subject of high community interest.
E. Increase New Plantings
• Prepare a detailed and comprehensive planting plan for City trees; examples of relevant
topics would include:
o “Right tree, right place” considerations such as species and size
recommendations for specific (1) planting locations (sidewalk parkway vs.
bulbout vs. street median vs. City park, etc.) and (2) sizes of planting spaces
(open, moderately constrained, highly constrained…)
o Installation procedures, such as proper use of compost, soil enhancement
technologies, irrigation, other equipment such as grow tubes, stakes, grates,
etc.
o Optionally, a brief section containing early-life maintenance tips
• Support and work with the 10 Tall campaign to plant 10,000 new trees within the City by
2035
o Achieve 100% stocking of the City’s approximately 350 empty tree wells
o Determine how many new trees the City’s parks can accommodate
o Conduct an equity analysis to determine where new plantings can best address
environmental injustice issues in the city
o Continue working with City partners to recruit volunteer labor for planting
events and, as possible, long-term care (e.g., watering)
▪ Consider using CCC or other labor sources for these purposes
▪ Ensure that whenever unskilled (e.g., volunteer) labor is used, adequate
training on the planting and care of trees is provided
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o Conduct outreach via online/social media poll, newspaper ads, utility bill inserts,
etc. to determine whether City property owners would be interested in an
annual, free tree giveaway and planting program
• Consider using street bulbouts for the planting of smaller street trees
• Consider modifying the City’s engineering standards for the number of street trees
required per linear foot in new development, e.g., from one tree every 35 feet to one
tree every 25 or 30 feet, based on species size at maturity or on a size class list, as
deemed appropriate by a City arborist
• Increase the City’s required tree removal replacement ratios, e.g., from 1:1 onsite/2:1
offsite to 2:1 onsite/3:1 offsite
o Alternatively, base required replacement ratios on calculated ecosystem
services value per tree, or on a specific percentage of total diameter removed
o In cases where it is not feasible for a property owner to replant, consider
allowing the owner to pay an in-lieu fee into a dedicated urban forestry fund, or
to donate a tree to the City or a City tree-planting partner
• Consider setting a minimum size requirement of 1.5” diameter at breast height (DBH)
for all new street and park tree plantings
• Wherever possible, position new plantings on the east or west sides of buildings to
maximize cooling from shade and reduce energy costs, while avoiding blocking the
southern exposure that provides passive solar heating during winter
• Evaluate an urban green roofs, walls, and balconies incentive program that could
incorporate small trees.
F. Focus on Sustainability
• Adopt “right tree, right place” as the City’s tree planting philosophy going forward
o “Right tree” means…
▪ Plant species that are considered suitable for urban spaces, provide
abundant environmental, social, and economic benefits, and are
climate-ready (hardy, tolerant of drought, heat, wind, etc.)
▪ Continue working with partners including Cal Poly San Luis Obispo’s
Urban Forest Ecosystem Institute (UFEI) and interested growers to
identify novel candidate species
o “Right place” means….
▪ Plant in locations that are most conducive to the long-term health and
growth of the desired species, or where structural soils or similar
technologies can be used to enhance tree growth potential (e.g., areas
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of poor soil conditions or with large amounts of impervious surface
nearby)
▪ Plant trees in locations where their benefits will be maximized (e.g., for
maximum shading of homes, buildings, parking lots, active
transportation corridors/hubs…) and/or where they are most lacking (in
greenery-poor parts of the city)
▪ Minimize potential for conflicts with urban infrastructure (e.g., under
power lines, atop underground utilities…)
• Consider using known tree health-enhancing soil amendments and/or technologies
when planting and maintaining trees
o The City may choose to use part of its required annual procurement of compost
under SB 1383 in this manner
o The City may choose to modify the Municipal Code or engineering standards to
require the use of technologies including engineered soils, soil cells, or other
products that enhance infiltration and root growth as a condition of new
development in areas with poor soil characteristics or extensive impermeable
surfaces
• Adopt a lifecycle perspective toward urban trees
o Prepare a detailed and comprehensive lifecycle plan for City trees which
includes succession planting and replacement strategies for aging street and
park trees
o Emphasize long-term tree care and health over merely “planting trees”
o Consider working with Cal Poly to establish an urban tree nursery, in which
students would grow trees for the City
o Plan for end-of-life removal and sustainable use of the lumber, including:
▪ Uses that store carbon indefinitely (e.g., furniture, fencing, art)
▪ Uses that generate landscaping products (e.g., compost, fertilizer)
▪ Uses that reduce fossil fuel dependence by generating bioenergy (e.g.,
biogas, biofuels)
o Work with the City’s external partners to publicize these uses
• Recognize the importance of age and species diversity in shaping the urban forest
o Revise, and plan for the ongoing revision of, the City’s master tree list(s) in order
to attain a palette of suitable, beneficial, and resilient species
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o Adhere to the rule of thumb described in Santamour (1990) that no single
species should represent more than 10% of the total population and no single
genus more than 20% (Santamour, 1990)
• Continue to coordinate with City partners to prepare for safety hazards including
wildfire, flooding, and hazardous trees as referenced in the City General Plan Safety
Element and the Multi-Jurisdictional Local Hazard Mitigation Plan
o Consider working with CalFire to create an updated wildland-urban interface
(WUI) fire severity map for the city
o Continue working with CalFire, the City Fire Department, and the Fire Safe
Council to publicize the importance of fire prevention efforts, including
defensible space regulations, on private property in the WUI
o Identify locations within the City’s creek drainages where flooding could be
exacerbated by fallen trees in the wake of storms, wildfires, or other large-scale
tree mortality events
o Take into account existing and projected disease/pest problems when making
species choices for purchasing and planting; consider reducing reliance on the
most heavily affected host tree species. Pathogens and pests of concern include
Monterey pine pitch canker (MPPC), sudden oak death (SOD), invasive shot hole
borer (ISHB), goldspotted oak borer (GSOB)
o Work with contractors and partners (SLO County, CalFire, Cal Poly, PG&E,
others) to monitor tree health citywide, including for unfolding pest and disease
infestations; plan for a coordinated response to threats
• Determine what the future holds for the Tree Committee
• Give high priority to water conservation in all urban forest-related actions
o Expedite the elimination of high water use tree species from the City master
tree lists; going forward, allow only drought-tolerant species/varieties to be
planted in the City
o Require installation (possibly temporary) of drip irrigation, using irrigation
timers, as deemed necessary to support new plantings for the first two to three
years
o Alternatively, consider requiring that each newly planted City tree be
accompanied by a small, buried reservoir (olla) that is easily filled and slowly
releases water into the ground; these may be porous clay pots or even
perforated plastic jugs
o Working together with City partners, perform outreach to property owners
about correct watering of trees during drought conditions
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o Modify City code to require that all aboveground watering (whether computer-
controlled or by hand) take place during the hours of 7 pm – 9 am every day
(i.e., prohibit watering between 9 am and 7 pm)
o Where possible, plant new trees near natural drainages (e.g., in open space)
o In hardscape areas, consider redirecting stormwater runoff to new plantings
o Mulch all new plantings; check once a year and add more mulch as needed
o Consider or pilot the use of technologies such as engineered soils, soil cells,
hydrogels, pervious (permeable) hardscape materials, etc. to improve soil
structure, water infiltration/percolation, and therefore overall tree health
• Make improvements to the City Municipal Code:
o Consider moving existing (or strengthened) City engineering standards around
tree planting and care (including irrigation) into the Municipal Code, as a means
of ensuring better outcomes in new development and landscaping
o Require that the City consider species diversity, age/size diversity, and climate
resilience when reviewing and approving planting plans for new developments
• Use up-to-date resources such as the USDA Forest Service’s recent guide, “Climate
Adaptation Actions for Urban Forests and Human Health” (Janowiak et al., 2021) to
guide City policy and actions; this publication’s strategies include the following:
o Activate social systems for equitable climate adaptation, urban forest, and
human health outcomes
o Reduce the impact of human health threats and stressors using urban trees and
forests
o Maintain or increase extent of urban forests and vegetative cover
o Sustain or restore fundamental ecological functions of urban ecosystems
o Reduce the impact of physical and biological stressors on urban forests
o Enhance taxonomic, functional, and structural diversity
o Alter urban ecosystems toward new and expected conditions
o Promote mental and social health in response to climate change
o Promote human health co-benefits in nature-based climate adaptation.
G. Address Issues Unique to Downtown
• Support implementation of the City’s Downtown Concept Plan (DCP) and Mission Plaza
Concept Plan (MPCP)
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• Continue to work with partners on additional downtown streetscape improvements
(e.g., tree or planter adoption, memorial benches/public art using recycled urban
lumber, the “rack with plaque” program) as described in the DCP
• Continue to support collaborative efforts between Public Works, the Office of
Sustainability, and City partners (e.g., Downtown SLO) to address tree-related problems
affecting the downtown area, such as sidewalk damage and undesirable conditions due
to insect and bird activity
• Consider requiring or incentivizing the creation of additional green infrastructure (e.g.,
green roofs, green walls) in public improvement projects in the downtown area
• Establish a “tree conservation corps” – possibly an expansion of the existing Downtown
Foresters volunteer group
• Consider creating and publicizing a walking tour of downtown that specifically calls out
unique or otherwise notable trees (e.g., Living Holiday Tree, Moon Tree) among other
points of interest
• Prioritize the evaluation and if needed, replacement, of downtown’s tree grates to
ensure both pedestrian safety and tree health.
H. Increase Outreach to Officials and the Public
• Continue to maintain the City’s decades-long Arbor Day Foundation designation as a
“Tree City USA”
• Work with City partners to create an “urban forestry community outreach week,” or
combine this with the City’s Earth Day celebrations
• Tie in urban forestry outreach with other City marketing/tourism-oriented programs
• Create a tree-focused downtown walking tour and/or a Citywide driving tour
highlighting unique or outstanding trees, and providing information on urban forest
facts and benefits on plaques or tree tags
• Initiate a program to provide financial support to income-qualifying private landowners
for needed care and maintenance of their trees
• Use more storytelling in the urban forestry program; honor volunteers, sponsors, etc.
• Promote the use of recycled urban lumber for projects like public art, furniture, sheds,
benches, planters, and so on in order to store the wood’s carbon indefinitely
• Try to attract statewide or national urban forestry conferences to San Luis Obispo (e.g.,
California Urban Forestry Council, Western Chapter of the International Society of
Arboriculture [ISA], …)
• Create a City community tree planting and care program (a “tree corps”) featuring
training by knowledgeable local stakeholders
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• Work with City partners, Cal Poly, and/or Cuesta College to create an urban forestry club
• Update/improve the City’s urban forest website
o Make the City’s pruning schedule/plan available to public
o Create a publicly viewable, interactive online map of all City-owned trees, a la
City of Santa Monica or Cal Poly SLO
o Require monitoring and annual reporting on urban forest to the public; this
could include dollar values as calculated via i-Tree Eco or similar software
• Create a mobile app for City residents to make service requests, report new tree
plantings, receive City urban forestry news, etc. (similar to Fresno’s “FresGO”)
• Support the development and use of the 10 Tall website.
I. Address Equity Issues
• Focus additional attention in City urban forest planning to parts of the city that are on
the lower end of the socioeconomic scale and/or currently have little in the way of
green infrastructure, for instance, as identified by American Forests’ Tree Equity Score
tool
• Work closely with residents in each proposed planting neighborhood to plan tree
plantings and maintenance, as resident buy-in and participation are crucial to build the
trust and pride that lead to long-term success
• Continue to conduct City outreach in, at a minimum, both English and Spanish
languages; consider additional languages as well, if deemed warranted based on US
Census data or other demographic information.
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XII. Next Steps
This draft Community Forest Plan was prepared in order to satisfy the “culminating experience”
requirement for the Master of City & Regional Planning program at California Polytechnic State
University, San Luis Obispo. The document therefore contains certain sections, such as
Methodology and Literature Review, which are more applicable to an academic research paper
than to a municipal planning document.
Over the next several months, the draft CFP will be revised and streamlined so that it adheres
more closely to the format of a proper municipal management plan. Implementation matrices
showing proposed timelines and budgets may be added. The results of a planned Public Works
study session with the City Council this summer or fall will likely inform these revisions. Once
deemed complete, the plan will be circulated to City staff for comments, edited again, and then
presented to the San Luis Obispo City Council for consideration and, it is hoped, adoption.
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XIII. References
Allan, R. P., Hawkins, E., Bellouin, N., & Collins, B. (2021). IPCC, 2021: Summary for Policymakers.
Retrieved from:
https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf
American Forests. (2022). Tree Equity Score. Retrieved from:
https://www.americanforests.org/tools-research-reports-and-guides/tree-equity-score/
Andrews, M. (No date). Heritage Trees: City of San Luis Obispo, California. Retrieved from:
https://storymaps.arcgis.com/stories/fbc1b607a9454c66b4fc643518bfc1df
Arbor Day Foundation. (2022). Tree City USA. Retrieved from:
https://www.arborday.org/programs/treeCityUSA/index.cfm?msclkid=532dfb1fb13211eca8855
5e5e54c800c#standardsSection
Arbor Day Foundation. (No date). Urban trees and private property. Retrieved from:
https://www.arborday.org/trees/bulletins/documents/093-summary.pdf
Ballinas, M., & Barradas, V. L. (2016). The urban tree as a tool to mitigate the urban heat island
in Mexico city: a simple phenomenological model. Journal of environmental quality, 45(1), 157-
166.
Bastin, J. F., Finegold, Y., Garcia, C., Mollicone, D., Rezende, M., Routh, D., ... & Crowther, T. W.
(2019). The global tree restoration potential. Science, 365(6448), 76-79.
Battaglia, M., Buckley, G. L., Galvin, M., & Grove, M. (2014). It’s not easy going green: Obstacles
to tree-planting programs in East Baltimore. Urban forests: Ecosystem services and
management, 125-152.
Bingham, C. (1968). American Planning Association: Trees in the City (PAS Report 236).
Retrieved from: https://planning-org-uploaded-
media.s3.amazonaws.com/legacy_resources/pas/at60/pdf/report236.pdf
Blackmar, E. and Rosenzweig, R. (2018). Central Park History. Retrieved from:
https://centralpark.org/history-of-central-park/
Bolund, P., & Hunhammar, S. (1999). Ecosystem services in urban areas. Ecological
economics, 29(2), 293-301.
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Boswell, M. R., Greve, A. I., & Seale, T. L. (2019). Climate action planning: a guide to creating
low-carbon, resilient communities. Island Press.
Buffalo, S. (2016, October 29). Dead trees beget new life. San Luis Obispo Tribune (Bizz Buzz
Extra), pp. 39-42.
Burden, D. (2006). 22 benefits of urban street trees. Glatting Jackson, Walkable Communities,
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City of San Luis Obispo Community Forest Plan C. Hamma
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City of San Luis Obispo
Work Plan
The tree work plan provides a roadmap by designating annual work to efficiently prioritize the
maintenance needs of all of city trees. The work plans do not account for changes in priority
maintenance needs. Staff will continue to schedule work based on the highest known maintenance
priority. The highest level of priority maintenance should occur first. In other words, if a tree is
recommended for a routine prune during the initial inventory collection, but a service request and/or
further inspection indicates a heightened maintenance priority, lesser priorities should be organized
accordingly.
Work plans include consideration for trees by geographic region. Years 1 through 5 correspond to
grouped Districts on the Paving Area Map. In all areas, any identified priority maintenance will be
followed by routine maintenance, and the establishment of an ongoing 5-year maintenance cycle.
Downtown is scheduled to receive maintenance every 2 years, other parts of the community are
scheduled to receive maintenance every 5 years. Trees that need more frequent maintenance are
considered “cyclebusters”. These trees are scheduled to receive maintenance every 3 years.
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The following Districts are included in each year:
x Year 1: District 1 and District 2, also addressing cyclebusters from District 4 and District 5
x Year 2: District 3 and District 9, also addressing cyclebusters from District 6
x Year 3: District 4 and District 5, also addressing cyclebusters from District 7 and District 8
x Year 4: District 6 and District 9, also addressing cyclebusters from District 1 and District 2
x Year 5: District 7 and District 8, also addressing cyclebusters from District 3 and District 9
The work plan is based on the maintenance needs of the October 2022 tree inventory of 12,427 City-
maintained trees along streets, in medians, parks, and at city facilities. Following the work plan, the
Urban Forest Services will provide routine maintenance to all trees during a 5-year period (Table 1).
Routine maintenance includes trees recommended for large and small routine prune as well as City
maintained, and trim poorly structured and trees with no maintenance recommendation. The type of
prune can provide managers with a general idea of the equipment needed to complete the task (small
routine prunes should not require climbing equipment or aerial lifts). The cost of pruning is priced by
the individual tree and the cost per tree increases as the size increases.
Patrol - diseased or declining includes 103 trees that have been flagged to receive periodic inspections
to ensure any future maintenance needs are noticed. This is estimated as a flat annual rate.
All known removals (103 trees) and stump grinding for existing stumps (139) are scheduled in year 1.
Year 1 removals will be added to the work plan as maintenance task stump grind in year 2. In years 2
through 5, an estimated 25 removals and stump grindings will occur each year. If trees continue to
receive proper maintenance this number may decline moving forward. Tree removal and stump grinding
are priced as a scale depending on the size (inch DBH).
Year 1- Work Plan
x Routine Pruning: 2,077
x Pruning - Cyclebusters: 375
x Patrol - Diseased or Declining: 8
x Tree Removal & Stump Grinding: 242 (sum of DBH: 3,969 for all Districts scheduled removals
and stump grind)
Year 1 Total Cost: $514,062
Year 2- Work Plan
x Routine Pruning: 2,552
x Pruning - Cyclebusters: 428
x Patrol - Diseased or Declining: 17
x Tree Removal & Stump Grinding: 10 (estimated sum of DBH: 384)
Year 2 Total Cost: $518,193
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Year 3- Work Plan
x Routine Pruning: 2,126
x Pruning - Cyclebusters: 376
x Patrol - Diseased or Declining: 21
x Tree Removal & Stump Grinding: 10 (estimated sum of DBH: 384)
Year 3 Total Cost: $508,141
Year 4- Work Plan
x Routine Pruning: 1,944
x Pruning - Cyclebusters: 469
x Patrol - Diseased or Declining: 50
x Tree Removal & Stump Grinding: 10 (estimated sum of DBH: 384)
Year 4 Total Cost: $587,565
Year 5- Work Plan
x Routine Pruning: 1,155
x Pruning - Cyclebusters: 502
x Patrol - Diseased or Declining: 7
x Tree Removal & Stump Grinding: 10 (estimated sum of DBH: 384)
Year 5 Total Cost: $451,602
Based on the work plan, the average cost of tree maintenance after establishment is approximately $50
a tree per year. This estimation can be used to project the cost of routine maintenance as the tree
inventory expands.
Planting Plan
The tree planting plan provides annual work plans for planting and maintaining new. The planting plan
is based on vacant sites and tree and stump removals from the October 2022 tree inventory. In total,
there were 414 available potential tree planting locations with an additional 242 sites becoming
available after the identified removals (103) and stump grindings (139) are addressed from the work
plan. The 414 available planting sites are addressed in the first two years of the planting plan. Plantings
are also scheduled in years 3 through 5, after removal and stump grinding occur for the 242 additional
sites. The cost of planting is priced by the individual tree and the cost per tree increases as the size
increases. The planting plan estimated 80% of plantings being 15-gallon containers and 10% in the two
larger sizes to accommodate larger trees in the downtown, main arterial roads and other frequently
visited areas. Newly planted trees are scheduled to receive training pruning and other young tree
maintenance such as regular watering, mulching, stake adjustment and removal. Trees are visited once
a week during establishment (first three years). The cost for young tree maintenance was determined
by estimating the amount of time staff spend on the task.
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Year 1- Planting Plan
x Tree Planting: 184 (Districts 1, 2 ,4, 5, and 9)
x Young Tree Maintenance: 1,869 (1,649 and the 184 new planted trees)
Year 1 Total Cost: $105,374
Year 2- Planting Plan
x Tree Planting: 230 (Districts 3, 6, 7, and 8)
x Young Tree Maintenance: 1,514 (2/3rds of the Year 1 trees scheduled for young tree maintenance
(1,100) and the Year 1 (184) and Year 2 (230) new planted trees)
Year 2 Total Cost: $112,141
Year 3- Planting Plan
x Tree Planting: 242 (all sites created from Year 1 and 2 removal/stump grinds in all Districts)
x Young Tree Maintenance: 1,448 (1/3 rd of the Year 1 trees scheduled for young tree maintenance
(550) and the Year 1 (184), Year 2 (230), and Year 3 (242) new planted trees)
Year 3 Total Cost: $112,141
Year 4- Planting Plan
x Tree Planting: 20 (estimated 10 removal/stump grinds from Years 2 and 3)
x Young Tree Maintenance: 492 (Year 2 (230) Year 3 (242), and Year 4 (30) new planted trees)
Year 4 Total Cost: $22,898
Year 5- Planting Plan
x Tree Planting: 20 (estimated 10 removal/stump grinds from Years 2 and 3)
x Young Tree Maintenance: 282 (Year 3 (242), Year 4 (20), and Year 5 (20) new planted trees)
Year 5 Total Cost: $16,641
This work plan and planting plan may be an over or under estima tion of the actual costs of maintenance.
Some reasons the costs may fluctuate follow:
x Certain events may cause increased maintenance needs (e.g., storm event, pest or pathogen
epidemic)
x Estimates are based on October 2022 data and the inventory is constantly changing
x Annual increases in the cost of maintenance was set to 5%, this may change
x Additional maintenance may be needed outside of the work plan
x Planting or maintenance goals change
x Several areas of San Luis Obispo may require additional maintenance, separate from the routine
work plan. For example, this may occur as clearance and safety pruning along bus routes and
areas of town that have higher pedestrian traffic such as parks and greenbelts. Trees in these
areas are candidates for more regular inspection and may involve heavier pruning than typical
block pruning.
Page 746 of 748
Table 1: 5-Year Work Plan Year 1 Year 2 Year 3 Year 4 Year 5 Total 5-Year Maintenance Activity Diameter Class (inches) Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Total Cost Routine Pruning - Trees Ϭ५ϲΎ $47 530 $25,043 $50 505 $25,054 $52 ϲϬϵ $31,725 $55 ϯϱϵ Ψϭϵ͕ϲϯϳ $57 207 Ψϭϭ͕ϴϴϵ $113,347 ϳ५ϭϮ ΨϵϬ ϳϵϵ Ψϳϭ͕ϱϮϲ Ψϵϰ ϭ͕Ϭϯϲ Ψϵϳ͕ϯϴϬ Ψϵϵ 751 $74,121 $104 528 $54,717 ΨϭϬϵ ϯϲϬ Ψϯϵ͕ϭϳϮ Ψϯϯϲ͕ϵϭϲ ϭϯ५ϭϴ $184 382 ΨϳϬ͕ϭϵϯ Ψϭϵϯ 552 ΨϭϬϲ͕ϱϬϮ $203 ϯϲϲ Ψϳϰ͕ϭϰϲ $213 521 $110,824 $223 270 ΨϲϬ͕ϯϬϰ ΨϰϮϭ͕ϵϲϴ ϭϵ- 24 ΨϮϲϴ ϮϬϵ Ψϱϱ͕ϵϲϬ $281 Ϯϲϯ Ψϳϯ͕ϵϯϵ ΨϮϵϱ 202 Ψϱϵ͕ϲϮϵ $310 238 Ψϳϯ͕ϳϲϵ $325 171 Ψϱϱ͕ϲϱϮ Ψϯϭϴ͕ϵϱϬ 25-30 $341 ϲϵ ΨϮϯ͕ϱϰϲ $358 ϴϵ Ψϯϭ͕ϴϵϬ Ψϯϳϲ ϭϬϲ Ψϯϵ͕ϴϴϬ Ψϯϵϱ ϭϲϯ Ψϲϰ͕ϯϵϭ $415 88 Ψϯϲ͕ϱϬϮ Ψϭϵϲ͕ϮϬϵ 31-ϯϲ Ψϰϵϵ ϰϵ ΨϮϰ͕ϰϯϵ $524 45 ΨϮϯ͕ϱϲϲ $550 42 ΨϮϯ͕Ϭϵϱ $577 70 ΨϰϬ͕ϰϭϲ ΨϲϬϲ 30 $18,187 ΨϭϮϵ͕ϳϬϮ 37-42 ΨϲϬϰ 22 $13,283 Ψϲϯϰ 20 ΨϭϮ͕ϲϳϵ Ψϲϲϲ 28 Ψϭϴ͕ϲϯϴ Ψϲϵϵ 25 $17,473 $734 14 $10,274 ΨϳϮ͕ϯϰϲ 43+ $788 17 $13,388 $827 12 Ψϵ͕ϵϮϯ Ψϴϲϴ 22 Ψϭϵ͕ϭϬϭ ΨϵϭϮ 40 Ψϯϲ͕ϰϲϱ Ψϵϱϳ 15 $14,358 Ψϵϯ͕Ϯϯϰ Activity Total(s) 2,077 ΨϮϵϳ͕ϯϳϲ 2,522 ΨϯϴϬ͕ϵϯϮ Ϯ͕ϭϮϲ $340,334 ϭ͕ϵϰϰ Ψϰϭϳ͕ϲϵϭ 1,155 ΨϮϰϲ͕ϯϯϴ Ψϭ͕ϲϴϮ͕ϲϳϮ Cyclebusters Palms Washingtonia sp. $121 50 Ψϲ͕Ϭϯϴ $127 17 $2,155 $133 ϯϵ Ψϱ͕ϭϵϮ $140 15 ΨϮ͕Ϭϵϳ $147 10 Ψϭ͕ϰϲϴ Ψϭϲ͕ϵϰϵ Date Palm $551 88 $48,510 Ψϱϳϵ 18 ΨϭϬ͕ϰϭϵ ΨϲϬϴ 171 ΨϭϬϯ͕ϵϮϲ Ψϲϯϴ 18 $11,487 ΨϲϳϬ 108 ΨϳϮ͕ϯϲϱ ΨϮϰϲ͕ϳϬϲ Other Palm spp. $300 54 Ψϭϲ͕ϮϬϬ $315 47 $14,805 $331 47 $15,545 $347 50 Ψϭϳ͕ϯϲϰ Ψϯϲϱ ϰϲ Ψϭϲ͕ϳϳϰ ΨϴϬ͕ϲϴϵ Ficus spp. Ϭ५ϲΎ $47 ϲ $284 $50 ϲ ΨϮϵϴ $52 5 ΨϮϲϬ $55 ϲ $328 $57 5 $287 $1,457 ϳ५ϭϮ ΨϵϬ 2 Ψϭϳϵ Ψϵϰ 12 $1,128 Ψϵϵ 3 ΨϮϵϲ $104 12 $1,244 ΨϭϬϵ 14 $1,523 $4,370 ϭϯ५ϭϴ $184 5 Ψϵϭϵ Ψϭϵϯ 15 ΨϮ͕ϴϵϰ $203 4 $810 $213 14 ΨϮ͕ϵϳϴ $223 15 $3,350 ΨϭϬ͕ϵϱϭ ϭϵ- 24 ΨϮϲϴ ϲ Ψϭ͕ϲϬϳ $281 ϭϲ Ψϰ͕ϰϵϴ ΨϮϵϱ 3 Ψϴϴϲ $310 22 Ψϲ͕ϴϭϵ $325 ϭϵ Ψϲ͕ϭϴϰ Ψϭϵ͕ϵϵϯ 25-30 $341 ϭϲ Ψϱ͕ϰϲϬ $358 ϯϲ ΨϭϮ͕ϴϵϵ Ψϯϳϲ ϲ $2,257 Ψϯϵϱ 48 Ψϭϴ͕ϵϲϮ $415 38 Ψϭϱ͕ϳϲϮ $55,341 31-ϯϲ Ψϰϵϵ 10 Ψϰ͕ϵϴϴ $524 ϭϵ Ψϵ͕ϵϱϬ $550 3 Ψϭ͕ϲϱϬ $577 27 Ψϭϱ͕ϱϴϵ ΨϲϬϲ 20 $11,518 Ψϰϯ͕ϲϵϰ 37-42 ΨϲϬϰ 0 $0 Ψϲϯϰ ϭϵ $12,045 Ψϲϲϲ 0 $0 Ψϲϵϵ ϭϵ Ψϭϯ͕Ϯϳϵ $734 ϭϵ $4,403 ΨϮϵ͕ϳϮϳ 43+ $788 0 $0 $827 ϲ Ψϰ͕ϵϲϭ Ψϴϲϴ 0 $0 ΨϵϭϮ ϲ $5,470 Ψϵϱϳ ϲ $5,743 Ψϭϲ͕ϭϳϰ Carrotwood Ϭ५ϲΎ $47 ϲ $284 $50 11 Ψϱϰϲ $52 2 $104 $55 13 $711 $57 ϵ $517 ΨϮ͕ϭϲϭ ϳ५ϭϮ ΨϵϬ ϱϲ $5,013 Ψϵϰ 55 $5,170 Ψϵϵ 31 Ψϯ͕ϬϲϬ $104 ϲϵ $7,151 ΨϭϬϵ 48 $5,223 ΨϮϱ͕ϲϭϲ ϭϯ५ϭϴ $184 57 $10,474 Ψϭϵϯ 88 Ψϭϲ͕ϵϳϵ $203 ϰϲ Ψϵ͕ϯϭϵ $213 ϵϮ Ψϭϵ͕ϱϳϬ $223 ϵϮ $20,548 Ψϳϲ͕ϴϴϵ ϭϵ- 24 ΨϮϲϴ ϭϵ $5,087 $281 43 ΨϭϮ͕Ϭϴϵ ΨϮϵϱ 15 $4,428 $310 38 $11,778 $325 32 $10,414 Ψϰϯ͕ϳϵϳ 25-30 $341 0 $0 $358 15 $5,375 Ψϯϳϲ 1 Ψϯϳϲ Ψϯϵϱ 14 $5,531 $415 ϭϲ Ψϲ͕ϲϯϳ Ψϭϳ͕ϵϭϴ 31-ϯϲ Ψϰϵϵ 0 $0 $524 4 ΨϮ͕Ϭϵϱ $550 0 $0 $577 5 $2,887 ΨϲϬϲ 4 $2,425 $7,407 37-42 ΨϲϬϰ 0 $0 Ψϲϯϰ 0 $0 Ψϲϲϲ 0 $0 Ψϲϵϵ 0 $0 $734 0 $0 $0 43+ $788 0 $0 $827 1 $827 Ψϴϲϴ 0 $0 ΨϵϭϮ 1 ΨϵϭϮ Ψϵϱϳ 1 Ψϵϱϳ ΨϮ͕ϲϵϲ Activity Total(s) 375 $105,040 428 Ψϭϭϵ͕ϭϯϮ ϯϳϲ Ψϭϰϴ͕ϭϬϵ ϰϲϵ $144,155 502 Ψϭϴϲ͕Ϭϵϵ $702,535 Patrol Diseased or Declining Ϭ५ϲ $150 1 $150 $158 5 $788 Ψϭϲϱ 5 $827 $174 17 ΨϮ͕ϵϱϮ $182 0 $0 Ψϰ͕ϳϭϲ ϳ५ϭϮ $150 3 $450 $158 3 $473 Ψϭϲϱ 7 $1,158 $174 11 Ψϭ͕ϵϭϬ $182 1 $182 $4,173 ϭϯ५ϭϴ $150 0 $0 $158 7 $1,103 Ψϭϲϱ 5 $827 $174 8 Ψϭ͕ϯϴϵ $182 2 Ψϯϲϱ Ψϯ͕ϲϴϯ ϭϵ- 24 $150 2 $300 $158 0 $0 Ψϭϲϱ 2 $331 $174 ϲ $1,042 $182 2 Ψϯϲϱ $2,037 25-30 $150 2 $300 $158 0 $0 Ψϭϲϱ 2 $331 $174 5 Ψϴϲϴ $182 0 $0 Ψϭ͕ϰϵϵ 31-ϯϲ $150 0 $0 $158 0 $0 Ψϭϲϱ 0 $0 $174 3 $521 $182 2 Ψϯϲϱ Ψϴϴϲ 37-42 $150 0 $0 $158 0 $0 Ψϭϲϱ 0 $0 $174 0 $0 $182 0 $0 $0 Page 747 of 748
42+ $150 0 $0 $158 2 $315 Ψϭϲϱ 0 $0 $174 0 $0 $182 0 $0 $315 Activity Total(s) 8 $1,200 17 ΨϮ͕ϲϳϴ 21 $3,473 50 Ψϴ͕ϲϴϮ 7 Ψϭ͕Ϯϳϲ Ψϭϳ͕ϯϬϵ Tree Removal & Stump Grinding $/in. DBH Sum DBH $/in. DBH Sum DBH $/in. DBH Sum DBH $/in. DBH Sum DBH $/in. DBH Sum DBH Tree Removal $58 ϵϭϮ ΨϱϮ͕ϲϲϴ Ψϲϭ ϭϵϮ Ψϭϭ͕ϲϰϮ Ψϲϰ ϭϵϮ $12,225 Ψϲϳ ϭϵϮ ΨϭϮ͕ϴϯϲ $70 ϭϵϮ $13,478 $102,848 Stump Grind Ψϭϵ 3,057 $57,777 $20 ϭϵϮ $3,810 $21 ϭϵϮ $4,001 $22 ϭϵϮ $4,201 $23 ϭϵϮ $4,411 $74,200 Activity Total(s) ϯ͕ϵϲϵ $110,445 384 $15,453 384 Ψϭϲ͕ϮϮϱ 384 $17,037 384 $17,888 $177,048 Program Administration All Maintenance Activity Total 2,702 2,977 2,533 2,473 1,674 12,359 All Cost Total $514,062 $518,193 $508,141 $587,565 $451,602 $2,579,564 Table 2: Maintenance by District District 1 District 2 District 3 District 4 District 5 District 6 District 7 District 8 District 9 Total Trees ϳϰϵ ϭ͕ϰϵϳ Ϯ͕Ϭϵϴ 1,205 1,127 1,488 ϱϮϵ ϳϵϲ ϳϱϲ Routine Pruning ϲϰϲ 1,431 2,055 ϭ͕ϭϬϵ 1,017 1,477 485 ϲϳϬ ϰϲϳ Cyclebuster Pruning 103 ϲϲ 43 ϵϲ 110 11 44 ϭϮϲ Ϯϴϵ Patrol - Diseased or Declining 5 3 14 ϭϵ 2 47 2 5 3 Tree and Stump Removal 14 23 38 14 ϵϮ 33 2 22 4 Total Maintenance Tasks 768 1,523 2,150 1,238 1,221 1,568 533 823 763 Table 3: 5-Year Planting Plan Year 1 Year 2 Year 3 Year 4 Year 5 5-Year Maintenance Activity Diameter Class (inches) Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Cost/tree # of Trees Total Cost Total Cost Tree Planting 15-gallon ΨϮϮϲ ϭϲϰ $37,023 $237 208 Ψϰϵ͕ϯϬϰ ΨϮϰϵ 218 $54,258 ΨϮϲϭ 18 $4,704 $274 18 Ψϰ͕ϵϯϵ $150,228 24-inch box $373 ϵ $3,355 Ψϯϵϭ 11 $4,305 $411 12 Ψϰ͕ϵϯϭ $432 1 $432 $453 1 $453 Ψϭϯ͕ϰϳϲ ϯϲ-inch box Ψϭ͕Ϭϳϲ 11 Ψϭϭ͕ϴϯϵ $1,130 11 $12,431 $1,187 12 Ψϭϰ͕Ϯϯϵ Ψϭ͕Ϯϰϲ 1 Ψϭ͕Ϯϰϲ $1,308 1 $1,308 Ψϰϭ͕ϬϲϮ Activity Total(s) $52,217 230 Ψϲϲ͕ϬϰϬ 242 $73,428 20 Ψϲ͕ϯϴϭ 20 Ψϲ͕ϳϬϬ ΨϮϬϰ͕ϳϲϲ Young Tree Maintenance Ϭ५ϭϮ ΨϮϵ 1,833 $53,157 $30 1,514 Ψϰϲ͕ϭϬϭ $32 1,448 Ψϰϲ͕Ϯϵϲ $34 ϰϵϮ Ψϭϲ͕ϱϭϳ $35 282 Ψϵ͕ϵϰϬ $172,012 Activity Total(s) 1,833 $53,157 1,514 Ψϰϲ͕ϭϬϭ 1,448 Ψϰϲ͕Ϯϵϲ ϰϵϮ Ψϭϲ͕ϱϭϳ 282 Ψϵ͕ϵϰϬ $172,012 Program Administration All Maintenance Activity Total 2,017 1,744 1,690 512 302 6,265 Cost Grand Total $105,374 $112,141 $119,724 $22,898 $16,641 376,778 Page 748 of 748
Urban Forestry Study Session
City Council Meeting
January 12, 2023
Overview
1.Recommendation
2.Background, Vision, History
3.Urban Forest Assessment
4.Operations, Current Status.
Tree Ordinance
5.City’s Climate Commitment
6.Community Forest Plan
7.10 Tall Tree Planting
8.Community Partners
9.Public Outreach
10.Implementation, Staffing, and
Funding
11.Focused Questions and
Council Feedback and
Direction
2
Recommendation
1.Receive a presentation on the current state of the Urban Forestry
Services Program
2.Provide direction to staff to guide the final Community Forest Plan
and implementation of a work plan in the 2023-25 Financial Plan.
Recommendation Background Vision History 3
Background
The Urban Forest Services (UFS) Program
within the Public Works Department is
responsible for:
1. Proactive and Responsive Maintenance
2. Community Education &Outreach
3. Tree Plantings
4. Staffing of the Tree Committee
5. Community Partner Liaison
6. Development Review
7. Municipal Code Enforcement
8. Heritage Tree Program
9. Pest Management
10. Tree Removal Applications
4RecommendationBackgroundVisionHistory
What is the Ideal Urban Forest?
5RecommendationBackgroundVisionHistory
Urban Forest Vision
The City of San Luis Obispo will beacommunityidentifiedandshadedbyadiverseurbanforest.RelyingontheCommunityForestManagementPlan,the City willactivelyencourageparticipationintreeplantingandstewardship,preserve and protect trees,promotepublicsafetyandtreehealth,implement cost effectiveenhancementandmaintenanceoftheforest,increase publicawarenessofthevalueofourcommunityforest,and maximizethesocial,economic,andenvironmentalbenefitsoftheurbanforestforcurrentresidentsandfuturegenerations.
6RecommendationBackgroundVisionHistory
1957
Urban Forest Historic Context
7RecommendationBackgroundVisionHistory
2018
Urban Forest Historic Context
8RecommendationBackgroundVisionHistory
1957
Urban Forest Historic Context
9RecommendationBackgroundVisionHistory
2018
Urban Forest Historic Context
10RecommendationBackgroundVisionHistory
Urban Forestry Program Assessment
Urban Forestry Program Analysis conducted by Davey Resource Group (2021)
11AssessmentOperations,
Code Climate Action CFP
Operations -Tree Pruning
Prior to 2019, City crews
performed most of the pruning.
Contract Funding was
increased in 2019 to $225k.
Overall program funding
increased starting 2019-20.
Approximately 40% of the City’s
Street Trees have been pruned
in past 18 months.
The City agrees with the
recommendation of Davey
Resource Group to perform
scheduled area pruning through
contractor services.
12AssessmentOperations,
Code Climate Action CFP
Operations -Tree Removals
Tree Removals are
identified during area
pruning operations, service
request, and inspections.
Historically, there was not a
process to ensure removals
were replanted in a timely
manner.
UFS agrees with the
recommendations of Davey
Resource Group pertaining
the tree removals.
13AssessmentOperations,
Code Climate Action CFP
Operations -Tree Planting
The City has partnered with Cal Poly to revise the Approved Street Tree List within the
2023 Engineering Standards update.
Species selection will focus on trees more adaptable to warmer climates and drought
conditions with the least potential for infrastructure conflicts.
The proposed work plan has projected removals and replacement plantings funded for
each zone, which is in alignment with the recommendations of Davey Resource Group.
14AssessmentOperations,
Code Climate Action CFP
Operations -Young Tree Care
▪Trees planted in locations
without irrigation require
manual watering for a
minimum of the first three
years.
▪One young tree (under 3
years of age) planted in an
unirrigated location
requires approximately 12
hours of care annually
during non-drought
conditions.
15AssessmentOperations,
Code Climate Action CFP
Commemorative Grove Program
The Commemorative
Program started in 1989
at Laguna Lake Park, and
now has over 400
trees.The Program is
currently on hold due to
staffing resources.
The location of the grove
may conflict with the
future expansion of the
park.
16AssessmentOperations,
Code Climate Action CFP
Tree Ordinance 12.24
17AssessmentOperations,
Code Climate Action CFP
Tree Removals 12.24.090 (E)
a.The tree is an imminent hazard to life or property, and
removing it is the only feasible way to eliminate the hazard
b.The tree is dead or dying or diseased or damaged beyond
reclamation
c.The tree’s roots are causing severe damage to public or
private property, and removing the tree is the only feasible
way to eliminate the damage
d.The tree is affected by structural defects and/or deficiencies
that will limit lifespan. The tree is densely clustered amongst
other trees and the requested tree removal promotes good
arboricultural practice
e.The tree is obstructing vision, access, or mobility or public
traffic
f.The requested tree removal is necessary to alleviate a
demonstrated and ongoing maintenance burden for the
property owner exceeding routine maintenance
18AssessmentOperations,
Code Climate Action CFP
Tree Removals 12.24.090 (G)
1.Size of tree. The scale of a tree shall be considered, as well
as the size of the tree’s canopy.
2.Location of Tree on Private Property. The location of the
tree on private property shall be considered.
3.Species of Tree. Native trees shall have a higher
preservation priority than non-native trees.
4.Forestry Best Practice. The number of healthy trees that a
given parcel of land will support shall be considered.
5.Public Right-of-Way Sidewalk Displacement. The tree is
obstructing vision, access, or mobility of public traffic.
6.Compliance with Compensatory Planting Requirements
(outlined in Section 12.24.090(J))
7.Heritage Tree removal is prohibited unless the City Arborist
authorizes a tree removal related to health or hazard.
19AssessmentOperations,
Code Climate Action CFP
Compensatory Plantings 12.24.090 (J)
Construction and Non-Construction Tree
Removals require the following
compensatory replanting:
Onsite 1:1
Offsite 2:1
Higher ratio replanting can be recommended to
decision maker by the Tree Committee and City
Arborist.
20AssessmentOperations,
Code Climate Action CFP
Tree Committee (M.C. 12.24.020)
A.The Tree Committee shall act as an advisory body
to the Director and City Council on all matters
relating to trees in San Luis Obispo.
B.The Tree Committee membership shall be governed
by the tree committee bylaws, as approved by the
Council.
21AssessmentOperations,
Code Climate Action CFP
City’s Climate Action Commitment
Climate Action Plan for
Community Recovery
Pillar 6:Natural Solutions
2023-2027 Tasks
1.1.A –Expand climate resilience and carbon
sequestration practices at additional
properties and sites in the City and broader
Greenbelt.
1.1.B –Make progress on protecting land
within the City’s Greenbelt through direct
purchases and conservation easements.
2.1.A –Adopt and implement the
Community Forest Plan and make
significant progress on the 10 Tall goal of
planting and maintaining 10,000 new
trees by 2035.
22AssessmentOperations,
Code Climate Action CFP
Well-regarded urban forest
plans from similarly sized
cities were reviewed during
preparation:Santa Monica,
Santa Barbara,Davis;also
San Francisco,San Jose.
The CFP is also intended to
provide city residents &
community members
with knowledge about urban
forestry and introduce them
to the 10 Tall tree planting
campaign.
The CFP is a public-facing
urban forest management
plan that provides
programmatic guidance
through a series of
established goals and
objectives.
The purpose of the CFP is
to implement the vision of
an equitable,sustainable,
climate-ready community
accruing multiple benefits
from City-owned trees.
Community Forest Plan (CFP)
23AssessmentOperations,
Code Climate Action CFP
1.Maintain and expand San Luis Obispo’s urban forest to maximize
environmental, social, and economic benefits for all, while minimizing
undesirable conditions
2.Adopt a “right tree, right place,” lifecycle-based perspective towards
urban trees which includes the planting, care, and end-of-life use of
climate-ready trees in locations where they will have the greatest
opportunity to thrive
3.Foster a spirit of collaboration between and within City departments
that are involved in urban forest management, as well as between the
City and other local stakeholders (e.g., community groups, nonprofit
organizations, utilities, SLO County, Cal Poly, other State agencies)
4.Educate and seek the involvement of City residents and visitors,
including historically marginalized groups, in order to obtain their buy-
in and support for a thriving urban forest.
Community Forest Plan -Goals
24AssessmentOperations,
Code Climate Action CFP
Plan Objectives
Objective 1.1:Design/Implement Program; Accrue and Analyze Data
Objective 1.2:Strengthen Maintenance Practices; Clear Backlog
Objective 1.3:Increase New Plantings/Implement 10 Tall Initiative
Objective 1.4:Reexamine Tree Removal and Mitigation Policies
Objective 1.5a:Focus on Sustainability:Climate Resilience
Objective 1.5b:Focus on Sustainability:Lifecycle Perspective
Objective 1.5c:Focus on Sustainability: Soil Enhancement and Stormwater
Objective 1.5d:Focus on Sustainability:Safety
Objective 1.5e:Focus on Sustainability:Water Conservation
Objective 1.6:Address Issues Unique to Downtown
Objective 1.7:Increase Outreach to Officials and the Public
Objective 1.8:Focus on Equity
Community Forest Plan -Objectives
25AssessmentOperations,
Code Climate Action CFP
10 Tall Initiative
The City’s Climate Action Plan calls for an ambitious tree
planting campaign of planting 10,000 new trees by 2035. Below
are estimated quantities of trees to be planted in different areas.
Proposed Locations Number of Trees to be
Planted
Streets, Parks, Right-of-Way 1,000
Creeks and Open Space 2,000
Engineering Standards for New
Development
3,000
Volunteers and Community Partners 1,500
Community Private Plantings 1,500
Trees planted to date since 2020 CAP
(approximate)
1,000
Total 10,000
2610 Tall Partners Outreach Implementation
10 Tall Initiative
2710 Tall Partners Outreach Implementation
10 Tall Website:
Community Partnerships
2810 Tall Partners Outreach Implementation
Public Outreach
Public Outreach was
conducted over the last 18
months through:
Online Community Survey
Council Updates
Tree Committee Updates
and Discussions
CAP Stakeholder Meetings
2910 Tall Partners Outreach Implementation
Implementation –Staffing Strategy
3010 Tall Partners Outreach Implementation
Historical Funding
Historical Urban Forest Funding
2018-19 2019-20 2020-21 2021-22 2022-23
Operating $755,815 $950,277 $881,179 $430,741 $531,814
Capital 0 $175,000 $175,000 $640,000 $375,000
One-time
Funding
(Included in
Capital)
0 0 0 $350,000 $200,000
Total $755,815 $1,125,277 $1,056,180 $1,070,741 $906,814
31PartnersOutreachImplementationFunding
Implementation Funding
Existing Phased
Approach
Community
Vision
Staffing $264k $380k $465k
Maintenance $225k $370k $515k
Planting $50k $100k
Total $489k $800k $1,080k
3210 Tall Partners Outreach Funding
Questions for Council
1.What size program does the Council feel is appropriate?
2.Would Council prefer a full Urban Forest program implementation within the 2023-25
Financial Plan,Or would a phased approach to the full program be Council's desired
direction?
3.Is Council supportive of a bifurcated Urban Forest Services work program across
multiple City Departments?
4.What is Council’s preferred direction on continuing the Commemorative Grove Tree
Program?
5.Should staff provide a recommendation in the 2023-25 financial plan to evaluate the Tree
Ordinance as it relates to the compensatory planting pursuant to tree removals,after
input and guidance from the community and Tree Committee?
6.Does Council feel that the Community Forest Plan is heading in the right direction in
terms of goals and objectives?
7.Is Council supportive of a complimentary tree give-away or grant program for City
residents to plant trees on their property that will help achieve the 10 Tall initiative,as
well as the overall allocation of tree planting locations in order to meet the objective?
33Questions