Somerville Urban Forest Management Plan

22.8 MB·English

by  Somerville (Mass.) The Mayor's Office of Strategic Planning and Community Development

City of Somerville
Massachusetts
URBAN

FOREST

MANAGEMENT PLAN
2021
DRAFT
PREPARED BY:
Public Space Urban Forestry Division
Mayor’s Office of Strategic Planning
and Community Development
City of Somerville*
City Hall
93 Highland Avenue
Somerville, Massachusetts 02143
This document was adapted from an
Urban Forest Management report provided by:
Davey Resource Group, Inc.
1500 N. Mantua Street
Kent, Ohio 44240
800-828-8312
*This institution is an equal opportunity provider.
Notice of Disclaimer: Inventory data provided by Davey Resource
Group, Inc. “DRG” are based on visual recording at the time of in-
spection. Visual records do not include individual testing or analysis,
nor do they include aerial or subterranean inspection. DRG is not re-
sponsible for the discovery or identification of hidden or otherwise
non-observable hazards. Records may not remain accurate after
inspection due to the variable deterioration of inventoried material.
DRG provides no warranty with respect to the fitness of the urban
forest for any use or purpose whatsoever. Clients may choose to
accept or disregard DRG’s recommendations or to seek additional
advice. Important: know and understand that visual inspection is
confined to the designated subject tree(s) and that the inspections
for this project are performed in the interest of facts of the tree(s)
without prejudice to or for any other service or any interested party.
Photograph credit, front cover:
Victor Nascimento, City of Somerville
SOMERVILLE URBAN FOREST MANAGEMENT PLAN
TABLE OF CONTENTS
Vision Statement 2
Letter from the Mayor 4
Letter from the Urban Forestry Committee 5
Executive Summary 6
Introduction 12
Section 1: The Importance of Trees in the City 14
Section 1.1: Somerville’s Tree Canopy 16
Section 1.2: Somerville’s Street Trees 30
Section 2: Somerville’s Tree Inventory Data 42
Section 3: Expand, Preserve, and Maintain 68
Section 3.1: Tree Planting Plan 70
Section 3.2: Tree Maintenance Program 89
Section 3.3: Invasive Insect and Disease Management Strategy 109
Section 3.4: Storm Preparedness Plan 132
Section 4: The Road Map 156
Section 4.1: Operations Review 158
Section 4.2: Funding Analysis 182
Section 4.3: City of Somerville Tree Ordinance & Policy Review 191
Section 4.4: Public Engagement 205
Section 5: Action Plan 212
Glossary 228
References 236
Appendices
A. UTC Assessment Methodology 245
B. i-Tree Streets Inputs and Reports 254
C. Data Collection and Site Location Methods 264
D. Suggested Tree Species for Future Planting 275
E. Tree Planting 284
F. Risk Assessment and Priority and Proactive Maintenance 325
G. Invasive Pests and Tree Diseases 330
H. Tree Emergency Plan Worksheet 340
I. Potential Plantable Area by Ward 352
VISION STATEMENT

Somerville’s vision for its trees is
to create the best forest for a city,
and the best city for a forest.

This Urban Forestry Management Plan (UFMP)
serves as a guiding document for the expansion,
preservation and maintenance of a healthy and
diverse urban forest to maximize environmental,
economic, safety and aesthetic tree benefits for the
Somerville community today and in the future.
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This Somerville Urban Forest Management Plan was made possible by grant funding from the Massa-
chusetts Department of Conservation and Recreation in cooperation with USDA Forest Service and
through its Urban and Community Forestry (U&CF) Grant Program. The U&CF Grant Program is
designed to encourage communities to create and support long-term and sustained urban and com-
munity forestry programs throughout Massachusetts.
In addition, the following people were instrumental in completing this document:
City of Somerville, Mayor Joseph Curtatone Engineering Department
Brian Postlewaite, Director of Engineering
Office of Strategic Planning and Community Jess Fosbrook, former Director of Engineering
Development (OSPCD)
George Proakis, Executive Director Urban Forestry Committee
Luisa Oliveira, ASLA, Director,
Althea Northcross (co-chair)
Public Space and Urban Forestry
Chris Dwan (co-chair)
Vanessa Boukili, PhD, MCA, Senior Urban Jennifer Clifford
Forestry and Landscape Planner; Amy Mertl
Principal Author
Sharon Komarow
Malik Drayton, Urban Forestry Tori Antonino
and Landscape Planner Sarah Sweeting
Conor Guidarelli
Cortney Kirk, RLA, ASLA, Senior Public
Space Planner Henry Ayanna
Vanessa Boukili (ex-officio)
Arn Franzen, Senior Project Manager/
Mark Lawhorne (ex-officio)
Director of Parks
Andrew Louw, RLA, Public Space Planner
Special thanks to:
George Ackerson, Consulting Arborist at
Department of Public Works (DPW) Horticultural Technologies, Inc.
Jill Lathan, Acting Commissioner Keith Johnson, GIS Coordinator, IAM
of Public Works
All residents who read and gave thoughtful
Steven MacEachern, Commissioner comments on prior drafts of this document
of Public Works
Eric Weisman, Director of Operations
Graphic Design by:
Mark Lawhorne, Superintendent of Highways
Kim Schmidt Design
3
MAYOR’S LETTER
It is my pleasure to release Somerville’s first comprehensive Urban
Forest Management Plan. Trees are an essential part of our com-
munity both for quality of life and for our environment. They
provide shade, help to clean our air and stormwater, calm traf-
fic, increase property values, and are a vital component of making
Somerville the best place to live, work, play, and raise a family. Trees
are also a crucial part of our urban ecosystem as they are a source of
food and habitat for our city’s pollinators and other wildlife.
Trees provide us with countless benefits, and we need to take proper
care of them to help them survive in tough urban conditions. Reg-
ular tree maintenance will not only encourage proper growth and
longevity, but also support public health and safety.
This Urban Forest Management Plan provides a data-driven ap-
proach to understanding the current conditions and needs of
Somerville’s urban forest, as well as detailed recommendations to
grow our tree canopy. Not only does this Plan include an assessment
of the city’s complete public tree inventory and a canopy cover anal-
ysis of all public and private trees, but it also includes guidance for
maintaining our urban forest, planting more trees, improving our
urban forestry operations, and enhancing public engagement.
This Plan builds upon the important work and ideas provided in
Somerville’s Open Space and Recreation Plan (2016-2023), Somer-
ville Climate Forward (2018), and SomerVision 2040. All of these
plans call for the creation of an Urban Forest Management Plan and
identify a need to increase the City’s tree canopy. Now, with this
Plan, we have a framework for growing a healthier urban forest.
The pages that follow provide us with an understanding of Somer-
ville’s urban forest today and a roadmap for how to continue to
grow and improve it. As with all important things, it will take a vil-
lage to make our urban forest the best that it can be. City staff and
residents alike share an immense passion for Somerville’s trees and,
armed with this Plan, I am confident that together we can enrich
our urban forest!
Joseph A. Curtatone
Mayor
City of Somerville
4
Urban Forestry Management Plan
Foreword from the Urban Forestry Committee
City of Somerville
The Urban Forestry Committee (UFC) held its first meeting in July 2019. The formation of the
UFC came after recognizing that the city’s Tree Preservation Ordinance called for a committee
and in response to increasing public concern over the state of the urban forest after the removal
of trees on Beacon Street and along the GLX corridor.
The following pages contain the City’s newest Urban Forestry Management Plan. The
development of this document is a critical step in the process of building and protecting
Somerville’s urban forest. This document lays the foundation necessary to develop and maintain
tree plantings and other green spaces in our city over the next five to ten years. As with all
Somerville’s documents, this one will evolve over time according to science and our social
needs.
Trees in our landscape provide monetary benefit by way of energy costs, health benefits, and
crime reduction. They also provide ecological benefits through carbon sequestration, mitigating
urban heat, and providing food and habitat for insects, birds, and other animals who underpin
the very foundation of human existence. These benefits and how they are quantified are
outlined in detail in the following pages. What is more difficult to quantify is the value of
connecting and interacting with nature. Observing nature offers tremendous value: it connects
community, provides respite from busy and stressful lives, and creates learning opportunities for
our children. Learning about ecology, biodiversity, and the importance of healthy ecosystems
can lead to more formalized study, investigative research and career choice. These, in turn,
inform climate policy and create tools and structure for the protection of all wildlife.

The UFC recognizes the importance of the moment, how we need to modify our behavior if we
are to meet the challenge of the climate crisis. We are dedicated to serving the community and
helping to reach the goal of creating a sustainable and equitable pathway for planting,
maintaining, and protecting our urban forest and green spaces. This includes creating pollinator
corridors to support native insect populations, advocating for healthy soils, and championing
biodiversity. The UFC is aware of the decimation of our local insect, bird and wildlife
populations. The return of pollinators will be a crucial next step in the development of this plan.
We must commit to converting to sustainable and ecological landscaping habits and using
indigenous species in our public and private plantings. Although Somerville is only 4.1 square
miles, we are confident that our actions will inspire communities throughout the Commonwealth.

Sincerely,

The Urban Forestry Committee
January 28, 2021

UFMP Executive Summary 5
EXECUTIVE SUMMARY
As part of the City’s commitment to its urban forest, this Plan was developed by the City of
Somerville’s Public Space & Urban Forestry (PSUF) Division based on a tree inventory and
other research conducted by its consultant, Davey Resource Group (DRG). Somerville’s
trees provide a wealth of benefits to our residents, such as providing shade, cleaner air and
water, habitat for wildlife and pollinators, and safer streets, as well as increasing property values and
improving people’s quality of life. In addition to providing an overview of the existing state urban for-
est, this Plan creates a vision and road map for preserving and expanding our urban canopy. It includes
specific recommendations for addressing short-term and long-term maintenance needs for invento-
ried public trees, as well as suggestions for improving urban forestry operations and public outreach.
6 UFMP Executive Summary
Canopy Cover
STATE OF
THE EXISTING
Current: 14.6%
URBAN FOREST
Goal: 16%

An analysis of aerial imagery from 2018
reveals that Somerville’s tree canopy
covers 14.6% of the land area. Somerville
aims to increase canopy cover to 16%,
which will require preserving existing
Three Dominant
trees, and planting new trees on both
public and private property.
Tree Species
Three species comprise a large
percentage of the City’s trees.
A more diverse species
distribution is desirable to 1036 Ash Trees
assure biodiversity and health.
Threatened by Emerald Ash Borer
The 1036 Ash trees identified on pub-
lic property (and an unknown number
of ash trees on private property) are
threatened by the invasive insect Em-
44% Native
erald Ash Borer. The City is currently
using an organic insecticide to treat
Approximately 44% of the
City-owned ash trees that are healthy
inventoried trees are native to
enough to treat. A modified strategy
New England, whereas 16% of are
that includes additional removals and
invasive species as defined by the
replacements is recommended, as well
Massachusetts Prohibited Plant
as an educational outreach campaign
List. Increasing the proportion of
would help raise awareness of this pest.
native species and decreasing the
proportion of invasive species in
the population will be beneficial
for the ecosystem.
Somerville’s street trees
provide approximately
$1,047,466
14,486 sites recorded
in quantifiable annual
A total of 14,486 sites on publicly-owned
land were recorded during the 2018 tree ecosystem service benefits.
inventory: 13,604 trees, 255 stumps, and 627
vacant planting sites.
13,604 Trees
255 stumps
627 vacant
planting sites
UFMP Executive Summary 7
EXECUTIVE SUMMARY
REMOVAL
Municipal Tree Maintenance &
Total = 864 trees
Planting Recommendations High Risk = 11 trees
Moderate Risk = 200 trees
Low Risk = 653 trees
Stumps = 231
The many environmental and econom-
ic benefits that trees provide justify the
time and money invested in planting
and maintenance. Identified mainte-
PRIORITY
nance needs for the sites inventoried in 2018
include: tree removal (8% of inventoried sites), PRUNING
stump removal (2% of inventoried sites), tree
Total = 333 trees
pruning (64% of inventoried sites), young tree High Risk = 8 trees
training (19% of inventoried sites), and tree Moderate Risk = 325 trees
planting (4% of inventoried sites). These needs
can be divided into “priority” and “proactive”
maintenance.
ROUTINE
PRUNING CYCLE
Priority Maintenance Total = 7,593 trees
6-year pruning cycle
Prune ~1,265 trees per year
Maintenance should be prioritized by addressing
trees with the highest risk first. High and Mod-
erate Risk trees should be removed or pruned
immediately to promote public safety. Low Risk YOUNG TREE
trees should be addressed after all elevated risk
TRAINING CYCLE
tree maintenance has been completed. Trees
should be planted to mitigate removals and in- Total = 2,483 trees
3-year cycle
crease canopy cover.
Prune ~827 young trees per year
TREE
PLANTING
Goal number of trees to plant
= at least 350 per year
8 UFMP Executive Summary