Title: Florida's urban and urbanizing forests
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00091330/00004
 Material Information
Title: Florida's urban and urbanizing forests
Series Title: Florida's urban and urbanizing forests
Physical Description: Serial
Language: English
Creator: School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida
Publisher: School of Forest Resources and Conservation, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: January 2009
 Record Information
Bibliographic ID: UF00091330
Volume ID: VID00004
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


This item has the following downloads:

UrbanForest_newsletter_Jan_2009 ( PDF )

Full Text

Florida's Urban and Urbanizing Forests

Urban and Urbanizing Forests is an Extension Program of the School of Forest
Resources and Conservation, IFAS/UF

The State of Florida's Urban Forests

T he urban forest provides a
wealth of benefits to neighbor-
hoods and communities through the
reduction of energy consumption,
removal of pollutants from the air and
water, reduction in stormwater flows,
as well as providing recreational
opportunities and aesthetic beauty. At
the same time stresses from the
urban environment including air
pollution, increased impervious
surfaces, soil compaction and
pollution, and negligence reduce the
diversity and magnitude of these
benefits. There are also economic,
land value, maintenance, and human
health costs (e.g., allergies) associated
with urban forests.

To understand the benefits and costs
of trees we need to understand the
urban forest resource of a com-
munity. That is we need to know the
amount, size, location, distribution,
and condition of a community's urban
forest. We refer to these character-
istics as urban forest structure. The
urban forest structure of a com-
munity depends on land use, climate,
and people's preferences. However,
we also need to realize that urban
forests are dynamic and change over
time due to factors such as urban
development, windstorms, removals,
and growth.

As a first step towards understanding
Florida's urban forests we have begun
collecting baseline information for

several communities in Florida
including tree: numbers, sizes, species
composition, locations, and condition
based on a statistical sample of sites
in Gainesville, Miami-Dade County,
Pensacola, and Tampa. In 2006-
2008, several random and permanent
tenth acre sites were sampled and
measured using the USDA Forest
Service's Urban Forest Effects
(UFORE) (http://www.ufore.org)

Crown measurements, tree species,
land use conditions, shrub
characteristics, surface cover in-
formation and other data were used
to determine the urban forest cover
and total leaf area. Our sample
consisted of the "entire" urban forest
which consists of all trees on public
and private lands across several types
of landuses. In Gainesville (12,173
ha), and Tampa (30,304 ha), plots
were located inside the city limits,
while Pensacola plots included the
surrounding urbanized portions of
Escambia County (2,300 ha). Finally,
the entire urbanized area of Miami-
Dade County (161,450 ha) was
Continue on page 3

In this issue:

Urban Forest Strike

Science Corner

Student Spotlight 5

Urban Forest Strike Teams Assist Municipalities

After Natural Disasters

By Eric Kuehler, Technology Transfer Specialist
USDA Forest Service, Urban Forestry South

after natural disasters, such as
hurricanes and ice storms,
municipalities struggle to restore
normalcy to its residents. Tons of
debris must be removed from
roadways and people's yards and
thousands of street trees must be
assessed for hazards. Many times,
communities lack the expertise of a
professional arborist to properly
assess public trees for hazards, or if
a city has a professional on staff,
usually the job is overwhelming and
takes many months or years to
complete. It is during these times
that a municipality may wish they
had a staff of ten to 20 professional
arborists to properly estimate the
amount of vegetative debris that
will need to be removed and stored
and to properly determine which
public trees are salvageable or
should be removed to reduce
hazards to the public right-of-way.
Urban Forest Strike Teams
(UFST) use state agency certified
arborists from the Southeastern
states to help municipalities
respond and/or recover from
natural disasters by providing
post-disaster tree assessments and
debris estimation.

Following Hurricane Katrina,
volunteer arborists from around the
world were assembled by many
partners including the U.S. Forest
Service to help communities in
South Mississippi and Louisiana
retain as much of their urban forest
as was safely possible. The Urban
and Community Forestry state coor-
dinators from Virginia and North

Carolina, wanting to adopt this
concept, approached the U.S.
Forest Service to help them train
certified arborists employed by
their states in post-storm tree risk
assessment and debris estimation
in order to prepare for future natu-
ral disasters both within state and
regionally. These UFSTs are trained
to provide an estimate of vegetative
debris immediately following a
storm, risk assessment of the
remaining public trees following
the initial clean-up, and locating
and evaluating potential planting
sites to restore the urban forest

the extent of the damage in Baton
Rouge, the city forester estimated
that it would have taken him and
his crew nine months to do what
the UFST did in two weeks. The
UFST advisory committee is cur-
rently working with the Southern
Group of State Foresters and
FEMA to include this resource in
the Incident Command System for
increased efficiency.

For more information about the
Urban Forest Strike Team, visit

Urban Forest Strike
Team members Drew
Arnn, Virginia Depart-
ment of Forestry, and
John Slater, Arkansas
Forestry Commission,
document a failed tree
to be removed in a
Baton Rouge, LA park
after Hurricane Gustav.

Since the summer of 2007, approxi-
mately 40 state-employed certified
arborists have completed the
training from around the Southeast.
UFSTs were deployed to Oklahoma
following the December 2007 ice
storms, and Baton Rouge, Louisiana
following Hurricane Gustav where
they helped communities success-
fully negotiate FEMA reimburse-
ments for debris clean-up and
hazard tree mitigation. Because of

"...Strike Teams use state

agency certified arborists from

the Southeastern states to help
municipalities respond and/or

recover from natural

disasters by providing
post-disaster tree assessments
and debris estimation."

The State of Florida's ...
Con'tfrom page 1

We measured urban forest canopy cover or the sum of all
tree and palm crown cover in these sites. Figure 1 depicts
the percentage of tree and palm cover for these four
communities across all landuses. Gainesville and
Pensacola's urban forest is dominated by evergreen trees
where as in Miami-Dade County and Tampa there is a 2.8
and 7 percent palm cover, respectively in the forest.

STree Cover N Palm Cover



30 _28.1

10 -8.8
].8 Z

0 .5 10.5
Gainesville Pensacola Miami Tampa

Figure 1 City

Florida's urban forest are often cited as composed of a
diverse number of tree species. With our results we can
see that all four cities included non-native tree species.
Some of these non-native trees are invasive species, and an
increase in the number of invasive plants can pose a risk to
native plants if these out-compete and displace native
plants. Increased tree diversity can however, minimize the
overall impact or destruction by a species-specific insect or
disease. Approximately 60% of the tree population
sampled in Miami's urban forest is composed of non-native
tree species (Figure 2). Tampa's urban forest is almost
evenly split between native and non-native tree species,
where as Pensacola and Gainesville have more native tree
species in their urban forest.

Tree species and numbers also vary by land use (e.g.,
residential, commercial, parks, transportation, etc.). For

example, in residential land use, the top three tree or palm
species found in each community are presented in Table 1
(on page 6). Laurel oak was found to be the most common
tree per hectare in both Gainesville, Pensacola, and Tampa
at 23, 31, and 15 respectively (Table 1). Similarly, Carolina
laurelcherry was also present in the top three most
common trees but differ with Chinese tallowtree in

U Native 0 Non-native




8 45



Gainesville Pensacola Miami Tampa

Figure 2 City

Pensacola and slash pine in Gainesville. In Miami-Dade
County two palm species make up the majority of trees
found on residential land, where as two mangrove species
make up the majority of trees on residential land in Tampa.

In general, forested and vacant areas have more trees than
in residential areas while industrial and transportation
have the least number of trees per unit area. This is the
case for all four communities. Increased development,
hurricanes, tree pests and diseases, and planting and
removals by people will affect urban forest structure in the
future. Even though this information can not predict the
future of the urban forests it can be used to formulate
management goals and objectives that can maximize
benefits and minimize costs and risks to the community.

Continue on page 6

The Future of Florida's Urban Forest

By Dr. Wayne C. Zipperer, Research Scientist
USDA Forest Service

Science Corner

The first comprehensive assess-
ment of the nation's urban forest
was conducted by USDA Forest
Service research scientists in 2000.
These researchers reported that
urban areas constituted 3.5 percent
of the total land cover for the nation.
In these urban areas they found that
there were 3.8 billion trees and 27
percent urban tree cover. The
researchers estimated that in Florida
approximately 10.8 percent of the
state is classified as urban, but that
the urban trees cover only 18 percent
of the land. The Florida urban forest
contained over 169 million trees.

These values obviously have changed
since 2000. Urban land cover has
increased, but most likely the percent
of urban tree cover has declined
because of the increase in urban
growth and increased frequency of
major hurricanes. Prior to the recent
economic slow down, Florida was
adding 44 new residents every hour
of the day. We were consuming over
400 acres of forest land daily and
building over 800 miles of new roads
annually. This new growth is often
characterized by subdivisions with
little or no tree cover. The urban
forest that did exist in cities and
towns has been hammered by a flurry
of hurricanes. The loss of forest cover
does not bode well for the sunshine

"...Global climate change is
the wildcard in our
management and planning."

state where shade represents a neces-
sity for not only human comfort but
also energy conservation.

The US Census Bureau projects the
United States population to increase
by 140 million by 2050. The Brook-
ings Institute reported in 2004 that
50 percent of the infrastructure
needed to support the projected
population growth does not exist yet
and that the majority of the growth
will occur in the Southern and West-
ern regions of the country. Although
the current rate of new residents
being added in Florida has dimin-
ished, Florida is projected to add
another 18 million people by 2050.

What might be the future state of the
urban forest in Florida? Urban devel-
opment and catastrophic wind storms
(e.g., hurricanes, tornados) will con-
tinue to influence our urban forest. In
addition, global climate change will
need to be considered with respect to
species responses and management

How communities respond to this
new growth will significantly affect
the urban forest. With the current
slowdown in development, communi-
ties have the opportunity to examine
their land-use policies and tree ordi-
nances to further reduce canopy
losses from development. They also
have an opportunity to examine their
urban forest management plans to
determine how best to maintain

canopy cover for energy conserva-
tion and to make urban forests
more wind resistant, thus reduc-
ing losses to hurricanes. Home-
owners also need to be engaged by
providing educational material
detailing the importance of main-
taining canopy cover.

Global climate change is the wild-
card in our management and plan-
ning. For Florida, computer mod-
els forecast a hotter and drier
future. When one considers that
our urban areas are already 4-6F
warmer because of the urban heat
island effect, additional increases
in temperatures will significantly
increase heat stress on the urban
forest and humans. The energy
conserved through shading will be

To address the affect of climate
change on the urban forest, we
need to start planning by building
and maintaining a more resilient
urban forest To meet this goal,
each community needs an urban
forest management plan. This plan
should contain, at minimum the
following objectives: maintain
species diversity, a balanced
distribution of diameters and ages,
and a healthy forest through prun-
ing and removing diseased trees;
and plant the right tree in the right
spot Implementing these objec-
tives will make all the difference in
reducing the overall cost of
managing our urban forests, while
maximizing the benefits derived
from those forests.

Wayne can be reached by email at
wzipperer@fs.fed.us or by phone at
(352) 376-4576.

Broward County Homeowner...
Con'tfrom page 1

A survey was developed to capture homeowner
association (HOA) leaders' responses to questions
concerning their perceptions and attitudes about
the benefits as well as the costs of the urban forest
in their community. Surveys were mailed to 571
HOA leaders across Broward County in the summer
of 2008. The 22% of the HOA leaders responding to
the survey listed the top benefits of urban trees as
shade, aesthetics and beauty, unique community
character, and increased property values. These
same respondents also ranked hurricane damage
from trees, tree damage to sidewalks, roads, and
foundations, falling branches and trees on power
lines, and falling branches and trees on property and
cars as the main costs of urban forests.
When asked if they would like more trees planted in
their communities respondents showed an interest
in tree planting. HOA leaders were also asked to rate
factors that might influence their support for an
increased tree planting and maintenance program
in the county. Cost of maintenance and purchase of
new trees, homeowners' willingness, and cost of tree
and debris removal after storms were listed as
factors to consider before expanding planting
Although limited, this survey could indicate
Floridian's reasons for having trees in urban areas.
Despite HOA leaders showing an interest for more
trees, they are concerned about debris and
hurricane damage. Outreach efforts could focus on
proper planting, pruning, maintenance techniques,
and species selection that will improve hurricane
Insight into people's perception of trees can give
focus to expansion and education efforts towards
the urban forest With greater education in planting,
maintenance, and species selection benefits can be
increased and costs minimized. The right tree in the
right location will reduce costs in maintenance,
property damage, and the negative perception and
increase benefits of shade, aesthetics, and
environmental function. Increasing and protecting
the urban forests in today's expanding urban areas
is critical to the health of the community.
Jennifer can be reached by email atjacohen@ufl.edu.

We want to hear from you!
Let us know what topics and information you want
to see in future issues. Send ideas to Dr. Escobedo
at flurbanforests@ifas.ufl.edu.
requstig t beaddd tothee-nwsltte

Photo Credits

Pages 1 & 4: L a r yV. Korhnak* Page 2: Dudley Hartel, USDA
Forest Service, Urban Forestry South Page 5: Jennifer A.
Seitz* *contributors are from the University of Florida

Student Spotlight
Hi, I'm Alicia Lawrence, a
graduate student from Venice,
Florida, developing new growth
rate estimates for trees in
southern regions to better forecast
future growth and carbon
sequestration. Currently growth
rates are based off tree studies
from northern regions, and may
not accurately describe southern
grown trees. Forestry came to me
while appreciating the wild range
ecosystems I found across my


The State of Florida's ...
Con't from page 3

Table 1. The Three Most Common Tree and Palm Species Found in
Residential Land Uses for Gainesville, Pensacola, Miami-Dade
County, and Tampa, Florida.

City Tree and Palm Species Average Number of Trees costs. Since these sites are permanent
or Palms per ha they can be used to monitor changes
due to urbanization or hurricanes.
Gainesville Laurel oak 23
Tampa and other communities are
Carolina laurelcherry 21 beginning to use this information as the
Slash pine 15 basis for: enhancing the understanding
Pensacola La k 31 of the urban forest's values, improving
Pensacola Laurel oak 31
urban forest policies, planning and
Chinesetallowtree 11 management, and providing
Carolina laurelcherry 9 justification for the inclusion of trees

Miami-Dade Surinam cherry 6 within environmental regulations. This
information can also be used by
County Christmas palm 5 residents and planners to better
Live oak 5 manage this resource.

Tampa Black mangrove 30 For questions about the Gainesville,
White mangrove 16 Miami-Dade, or Pensacola urban forests
Laurel oak 15 contact Francisco Escobedo at
fescobed@ufl.edu and for questions
about Tampa's urban forest contact
This information for the first time has provided us a glimpse of Florida's Michael Andreu at mandreu@ufl.edu.
urban forests. Often this information is found only for specific trees,
parks, neighborhoods or for specific land uses. The information is Additional information about urban
currently being used to quantify the services and goods provided by all of forests in specific communities can be
the community's trees as well as to understand how to minimize the found at http://edis.ifas.ufl.edu/
TOPIC Urban_Forestry.

Urban and Urbanizing Forests Program


Dr. Michael G. Andreu Assistant Professor
Dr. Francisco Escobedo Assistant Professor P 3
Melissa H. Friedman Biological Scientist
Jennifer A. Seitz Extension Associate *

"We address the issues surrounding expanding urban
areas and to understand forest ecosystems in and
around urban areas and their multiple functions."
Visit Our Web Site

University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs