SPRING/SUMMER 2006
U rban Forest
RESEARCH
USDA Forest Service • Pacific Southwest Research Station • Center for Urban Forest Research
InThis
Issue
Page
Title
1
Using Volunteers to
Effectively Collect
Tree Data
3
New Research in the
Works:
3
L.A.'s Million Trees
Initiative
3
Oakland Watershed
Restoration and
Protection Study
4
Sacramento Air Quality
Initiative Project
5
Green Streets
Stormwater
Management System
Using Volunteers to
Effectively Collect Tree Data
Using volunteers to collect
tree data is nothing new.
But, as some communities
have experienced, using
them effectively is still a
challenge. Are there steps
you can take to make the
process more effective?
That was the question we
wanted our study to answer.
During the summer of 2004,
89 trained volunteers conducted a sample street tree inventory in Minneapolis, MN. We were present to
conduct an evaluation of the process and the outcomes. After training sessions,
inventory data were collected using the new i-Tree software application by
entering data into a PDA (personal digital assistant). To measure the accuracy
of the volunteer’s data we compared a 10% sub-set of their data to data collected by professionals.
The City of Minneapolis, Minnesota was chosen as a pilot city for testing the new
i-Tree suite of software tools (www.itreetools.org). The Minneapolis Parks and
Recreation Department had cataloged approximately 25% of their estimated
200,000 trees. A second reason for selecting Minneapolis was the presence of
the Tree Trust. The Tree Trust has a 30-year history of leading local urban forestry efforts. Because of its experience and expertise, the Tree Trust was well
positioned to organize a large group of volunteers. Our evaluation focused on
the use of i-Tree’s STRATUM program to estimate the structure, function, and
value of the street tree population. Volunteers were trained to collect standard
inventory data for randomly selected city blocks throughout Minneapolis.
Tree data collection began on
August 18, 2004, and was nearly
complete by September 13, 2004.
Volunteers were organized into 20
teams, and they collected data on
4,577 trees from 405 city blocks.
We compared the accuracy of 431
trees inventoried by volunteers
and professionals and found that
volunteers correctly rated leaf
condition (81%), species (80%),
and tree size (diameter at breast
height) (77%). Volunteers and professionals agreed less frequently
on the condition of each tree’s
wood (69%), tree root–sidewalk
conflicts (66%), recommended maintenance (49%),
and priority task (9%).
STRATUM CASE Study
Evaluation in Minneapolis,
Minnesota
training, and cover their maintenance and
downloading.
• Before training, determine (via questionnaire)
which volunteers want to survey trees in their
neighborhoods, allow them to self-select
teammates, and form teams early during the
training session so they can network.
• Produce a training manual that clearly addresses
the different data fields.
• Cover street side safety tips during training and
in the manual.
• Conduct a walking/windshield survey of each
city block to verify its existence, extent, and clear
designation on the map. Have replacement city
blocks ready for each zone.
• Develop a formal troubleshooting process
before deploying volunteers so that people in
the field know who can answer specific types of
questions.
• Have a “refresher session” soon after data collection
From surveys and interviews we found several rebegins to review solutions to the most common
curring themes. These themes included scheduling
questions and problems.
difficulties within teams, a much more extensive
time commitment than originally thought, difficulty
determining genus and species of a tree, and frustra- We believe that trained volunteers can be a valuable
tions with inadequate information on how to assess resource for acquiring information on tree numbers,
the condition and management needs of a tree. In species, and sizes. However, their assessments of
our report we offer suggestions to address these tree maintenance needs, condition, and conflicts
were less reliable, due largely to the level of trainconcerns, with key points summarized below:
ing they received. For example, the information on
• Estimate the amount of time required to conduct how to collect data was unevenly presented, and
the inventory (average of 6 minutes per tree in resulted in low accuracy ratings for data fields that
Minneapolis), then recruit a sufficient number of were not clearly explained. We believe that with a
volunteers, remembering that asking for more more focused training regime, volunteers can make
than 8-12 hours may reduce participation. Clearly
communicate your time expectations to the reliable determinations regarding tree condition
and management needs for purposes of managevolunteers.
ment planning. Lessons learned from this study
• Train volunteers on use of the PDA, maps, and tree
assessment in one 6-hour day. Conduct a separate have been incorporated into STRATUM and recom3-4 hour session on tree identification. Have a mendations can apply to a broader audience than
“dress rehearsal” during this session. Use the maps, i-Tree users. See the full report at: http://www.fs.fed.
PDAs and data collection kits to locate and survey
us/psw/programs/cufr/products/cufr_660_Minneall trees in one city block.
apolisCaseStudy_12-05.pdf
• Focus tree identification on key distinguishing
features of commonly mistaken trees among the
10-15 most abundant species.
—Jim Geiger
• Develop a slide library that shows trees with
different maintenance needs and condition
ratings. Use this during training and include it in
the training manual.
• Demonstrate how to troubleshoot PDAs during
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Spring/Summer 2006
Urban Forest Research
New Research In The Works
LA’s Million Trees Initiative
With proper design and implementation, one million new trees in Los Angeles, California would
create an extraordinary environmental legacy
and serve as a watershed for other environmental
change. This initiative is championed by Mayor
Antonio Villaraigosa and is being implemented
through coordination of several city departments
and local non-profit groups. Guidelines for selection
of the one million trees will emphasize maximimum
sustainability, and will include a preference for California-friendly, native and drought-tolerant plants;
diversity of species; appropriate variation of tree
age; and site suitability.
THE NEED
Rapid growth in the Los Angeles region is accelerating air quality problems, water shortages, and storm
water management challenges. Mayor Villaraigosa
has already charted a course for sustainable growth,
and his plan to plant one million trees in the next
four years demonstrates the relevance of urban
and community forestry to the environmental and
economic health of Los Angeles.
Urban and community forestry solutions will
protect and restore environmental quality while
enhancing economic opportunity. Community
trees can improve air quality, manage storm water
runoff, mitigate water shortages, conserve energy,
enhance public health, increase land values and
local tax bases, provide job training and employment opportunities, reduce costs of city services,
and increase public safety.
OUR CENTER’S RESEARCH
We are producing science-based information on the
extent of the tree canopy cover and planting opportunities for planning purposes as part of our canopy
cover analysis for Los Angeles. For instance, initial
findings indicate that one million trees will increase
canopy cover from about 21 to 31%. We are also
calculating the future urban forest’s role in improving air quality, reducing energy costs, intercepting
rainfall, reducing runoff, and providing important
social and economic benefits. The satellite imagery
Urban Forest Research
acquired for this study will be used later to identify
greening opportunities on a parcel-by-parcel scale,
as well as to track future canopy cover change.
www.milliontreesla.org
THE COMMUNITY’S ROLE
The City will work with the local community to plant
many of the one million trees—a large percentage
through reforestation and habitat restoration of
city park property. Special attention will be given
to schools, under-served communities and the Los
Angeles River. Community and business groups
will plant and maintain trees on private property.
Individuals will be encouraged to voluntarily plant
and maintain trees and record their efforts on a Web
site database. The Web site (www.milliontreesla.
org) will show the tree count and offer a toolkit of
information and links to resources. Completion of
this project is set for Spring 2007.
Three concurrent levels
of effort
1.Strategic effort, including
habitat restoration on park
lands
Oakland Watershed Restoration
and Protection Study
The study site is Oakland’s Ettie Street watershed, a
1.8 square mile watershed on the eastern edge of
the San Francisco Bay. The watershed contains predominately commercial, industrial, and residential
land uses. Urban Releaf is planting 1,800 trees. The
Center for Urban Forest Research is studying the
trees’ ability to reduce runoff and improve runoff
quality. Objectives are to:
2. Public-private
partnerships
3. Individual plantings
• Evaluate the effect increased tree cover will have
on:
- Reducing flooding and erosion
- Lowering contaminants entering storm
drains
- Improving water quality in the watershed
• Determine the kinds of contaminants entering the
Bay and demonstrate the benefits of urban trees in
reducing contaminated storm water runoff.
• Raise awareness of the degraded quality of the
watershed.
• Support local residents in planting and caring for
trees and restoring watershed health.
Spring/Summer 2006
3
URBAN RELEAF, OUR COMMUNITY PARTNER’S,
ROLE
With funding from the California Bay-Delta Authority, Urban Releaf is directing the planting of 1,800
trees (600 per year) within the Ettie Street watershed. Youth from Urban Releaf, East Bay Conservation Corps, and the Oakland Unified School District
are active in tree planting and stewardship activities. Others who are planting trees and distributing
information to the public include property owners,
non-profit organizations, business owners, local
officials, and volunteer groups. A volunteer-based
tree monitoring program is being developed to
track tree survival, health, growth, and performance
over the long term. This project is expected to be
completed by Summer 2007.
THE NEED
Oakland Watershed
Restoration and
Protection Project
Because land surfaces in the Ettie Street watershed
are largely impervious, most rainfall runs into storm
drains, and is then pumped directly into the Bay. The
volume of runoff and water quality are at dangerous
levels during certain storm events. And no formal
assessment or monitoring has been conducted in
this watershed.
This and other East Bay watersheds are the last
opportunity to regulate flows into the Bay from
the upstream Delta system. Highways, streets, and
parking lots in the watershed are major sources of
heavy metals, sediment, oil, and grease. Rooftops in
the watershed are sources of coliform bacteria from
birds, copper and zinc from gutters, and nitrogen
and phosphorous from atmospheric deposition.
The watershed’s sparse tree canopy contributes to
storm water runoff problems. Rainfall interception
by the urban forest could reduce the volume of runoff, but few studies have been conducted to measure the effectiveness of trees in urban settings.
OUR CENTER’S RESEARCH
We are helping to train volunteers, who are collecting data on the urban forest resource and monitoring watershed health. We are measuring the effects
of increasing tree cover on both the quantity and
quality of runoff. Also, we are modeling how annual
and peak runoff will change as trees mature over a
40 year period.
4
Spring/Summer 2006
Sacramento Urban Forest for
Clean Air Project
Our Center is working with the Sacramento Tree
Foundation (STF) and local air quality management
districts to evaluate the effectiveness of large-scale
tree planting on the future air quality of the Sacramento Region.
Using this information, we are developing a preliminary revision to the State Implementation Plan (SIP)
that includes tree planting as an ozone reduction
strategy. The U.S. Environmental Protection Agency
(EPA) will evaluate this revision from a policy and
technical perspective. A more detailed study may
result from their findings. If large-scale tree planting
is accepted in the SIP, a new source of funds for tree
planting and stewardship will become available for
implementation of the regional Greenprint. http://
www.sactree.com/aboutUs/programsServices/
greenprint/greenprintOverview.html
THE NEED
The Sacramento Metropolitan Area is among the ten
most ozone-polluted regions in the United States. The
Sacramento Region is designated as a serious ozone
“non-attainment area” by the U.S. EPA. The Sacramento region is also among the most polluted areas
for short-term particle pollution (24-hour PM2.5),
with diesel exhaust being a primary culprit.
The six million existing trees in the Sacramento region are removing approximately 1,600 tons of air
Urban Forest Research
pollutants annually. However, this “tree effect” addresses only 2% of the air pollutants emitted every
year. Scientific studies have identified a significant
number of air quality improvements that can be
expected from the urban forest
diverse mix of species. They are also considering
implementation strategies and developing methods
for tracking progress to verify that projected ozone
reductions are being obtained. This project is set for
completion by Fall 2007.
OUR CENTER’S RESEARCH
We are calculating the effects of trees on air quality
using existing models and statistical analyses. We
are developing air quality estimates for different
planting scenarios that include various levels of
canopy cover increase, high and low mortality rates,
and several tree species mixes. Regional GIS databases showing existing and future development
are being used to develop realistic future canopy
cover projections. Our models are providing initial
estimates of other benefits associated with selected
tree planting scenarios.
THE ROLE OF STF AND COMMUNITIES
The Sacramento Tree Foundation’s Greenprint has
been adopted by 28 local communities as a shared
vision for increasing the region’s tree canopy cover.
STF is helping develop realistic tree planting scenarios that optimize urban forest composition to
maximize air quality benefits while maintaining a
A Green Streets Storm
Water Management System
for Paved Areas
Developing green infrastructure technologies that
protect water quality by reducing contaminants in
urban runoff is gaining interest among regulators,
developers, and consultants. Our research currently
involves quantifying the benefits tree crowns have
on runoff reduction. With this project we can build
on that existing knowledge by studying how the
use of structural soils can enhance the role that trees
play in onsite storm water management.
OUR CENTER’S RESEARCH
We are developing and evaluating a storm water
management system that directs water to a reservoir
of structural soil under pavement. Structural soils are
engineered to support vigorous tree growth and
reduce root and hardscape conflicts, as well as be
load-bearing. Trees are an integral part of the system
Cornell University Urban Horticulture Institute
CU-Structural Soil Graphics and Plan Views
www.hort.cornell.edu/uhi/outreach/csc/index.html
www.hort.cornell.edu/uhi/outreach/csc/graphics.html
Urban Forest Research
Spring/Summer 2006
5
by first intercepting rainfall to reduce runoff rates,
and then removing water from the reservoir with
their root systems. Using these engineered soils as
runoff treatment and storage sites is a new idea.
Key to our system is its ability to be used in ordinary
situations with no additional land area required. All
developers and municipalities should be delighted
to have a beautiful, compact, shaded parking lot
with plenty of parking spaces but no runoff—or a
shady broad avenue with arching trees and little
or no runoff.
These ideals seem impossibly distant from most
development today, which provides precious little
space for trees. We are working to increase space
for trees by integrating them into the engineered
storm water management system in ways that
minimize conflicts and make efficient use of valuable land area.
PHASED APPROACH
Phase 1—Prototype Development: We are evaluating the physical and biological characteristics of different systems using two readily available structural
soils, Cornell University Soil and Carolina Stalite.We
also developed a new engineered soil (Davis Soil),
using local materials. We are concluding laboratory
tests to determine water storage capacity, water
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Send comments or suggestions to:
Shelley Gardner
movement, structural stability when saturated, and
ability of trees to remove water from a structural soil
reservoir. We collected polluted runoff from parking
lots and streets to test each system’s ability to remove pollutants. The composition of the runoff was
analyzed before and after passing through filtration
cells filled with each type of structural soil.
Phase 2—Demonstration: Selected systems are being installed in several locations for testing. During
this phase we are measuring runoff flowing into and
out of the systems under a variety of rainfall events
to evaluate their field performance and to calibrate
the runoff/storage relationships that we developed
in Phase 1. This research is being conducted with
assistance from our partners in Blacksburg, VA and
Ithaca, NY.
WHAT IS SUCCESS?
Success will mean increased benefits from urban
trees for those responsible for managing storm
water, trees, streets and utilities. Consequently, we
will target our findings for an array of constituencies, especially municipalities, engineers, landscape
architects, planners, and public works professionals.
By demonstrating innovative ways to integrate trees
into the infrastructure of cities, we are facilitating the
development of greener cities. This project is set for
completion by Fall 2007.
Urban Forest Research
is a publication of the Center for Urban Forest
Research, Pacific Southwest Research Station, USDA
Forest Service. For more information, contact the
Center c/o Department of Plant Sciences, Mail Stop 6,
University of California, 1 Shields Ave, Suite 1103,
Davis, CA 95616-8587. (530) 752-7636
USDA is an equal opportunity provider and employer, and
prohibits discrimination in all programs and activities.
Editor: Jim Geiger and Shelley Gardner
Production: Studio66
Center for Urban Forest Research
Pacific Southwest Research Station
USDA Forest Service
c/o Department of Plant Sciences
Mail Stop 6, University of California
1 Shields Avenue, Suite 1103
Davis, CA 95616-8780
or contact shelleygardner@fs.fed.us
We conduct research that demonstrates new ways in which
trees add value to your community, converting results into
financial terms to assist you in stimulating more investment in trees.
Check Out Our Website
www.fs.fed.us/psw/programs/cufr/
Urban Forest Research
Spring/Summer 2006
6