www.urban-forestry.com 39
Database Captures Urban Tree Sizes,
Growth Rates across United States
The U.S. Forest Service's Pacific Southwest
Research Station recently published a
technical manual
and launched the most extensive
database available
cataloging urban trees with their projected growth tai-
lored to specific geographic regions.
"Knowing a tree's maximum size can avoid future con-
flicts between roots and sidewalks or branches and
power lines," said Greg McPherson, research forester
for the Forest Service and lead author of the technical
report and database.
The products are a culmination of 14 years of work, ana-
lyzing more than 14,000 trees across the United States.
Whereas prior growth models typically featured only a
few species specific to a given city or region, the newly
released database features 171 distinct species across
16 U.S. climate zones. The trees studied also spanned
a range of ages with data collected from a consistent
set of measurements.
"There are very few studies, if any, in the world that can
compare to this in terms of scope with regard to the
number of trees studied, the species analyzed, the geo-
graphic range and ages, and so forth," McPherson said.
Advances in statistical modeling also have given
the projected growth dimensions a level of accuracy
never before seen. Moving beyond just calculating a
tree's diameter or age to determine expected growth,
the research incorporates 365 sets of equations to
project growth.
"Although tree growth is the result of complex process-
es, growth equations capture changes in tree size with
age in a surprisingly simple and accurate way," said
Natalie Van Doorn, a research urban ecologist with the
Forest Service and co-author on the study.
In addition to predicted tree growth, the manual
provides species-specific data on foliar biomass, or
amount of foliage, that is critical to projecting uptake
of air pollutants.
Written in a way to be accessible to non-technical users,
the technical report gives step-by-step instructions on
how to use the equations to calculate tree dimensions,
biomass, carbon storage and other features of interest
to urban foresters.
"The research and publication were done with the urban
forester and city planner in mind," Van Doorn said.
"Urban trees benefit communities in innumerable ways,
and it's this information can help communities make the
most of these natural resources."
SMA News
2017 Internship Program
SMA members may
apply to host a sum-
mer intern for ten
weeks or—new this
year—they may apply
for an intern to help
with a specific proj-
ect, with the hours
to be determined by
the project needs.
Also new this year,
SMA members may recruit a student intern from a local edu-
cational institution. Read more to learn the details, download
our 2017 internship flyer, and complete an online application at
www.urban-forestry.com.
Oct 15-20, 2017 – Details to come at
www.urban-forestry.com
2013 SMA Interns
Save the Date:
The First-Ever MFI Canada!
Cornwall, Ontario