Trees & plants

              Trees & Plants:
Benefits to the Community
Natural Architecture
Soil type, water and sunlight help determine the types
of plants that can grow in an area. Plants in turn provide
the “ natural architecture” of a region, supplying shelter and
food needed by animals and making every place unique. In
North Carolina’s coastal region, plants help create special
habitats including marshes, wetlands, maritime forests,
dunes, pine savannas, and beds of underwater plants ( known
as submerged aquatic vegetation) such as shoalgrass. These
resources provide homes for species that range from blue
heron and black bear to fl ounder and shrimp.
Humans accrue benefi ts from all of these natural
resources. But as communities develop, some loss of
vegetation usually results — along with the value, and goods
and services those plants provide. The amount and type
of plants lost will determine the scale of the impact. For
example, evergreen trees generally intercept more water than
a comparably sized deciduous tree. And some tree species are
better than others at fi ltering pollution from the environment.
Alone or in groups, trees provide benefi ts to our communities. ( Adapted from: Cooling Our Communities – A
Guidebook on Tree Planting and Light- Colored Surfacing, U. S. Environmental Protection Agency, January 1992.)
Plants — whether they are trees, bushes or a forest — play important roles in community health. Loss or
degradation of vegetation, especially in large quantities, can lead to major impacts on water resources,
economies, fi sheries and wildlife. Loss of even one mature tree can impact the way a piece of property is
used and enjoyed.
Environmental Services from Trees
Fact Sheet
Sustainability Series
1 2 3
LEAVES: Re-lease
water in the form
of water vapor, cooling the
surrounding air.
BRANCHES
AND LEAVES:
Provide shade and reduce
wind speed.
ROOTS,
LEAVES AND
TRUNKS: Provide habitat for
birds, animals and in-sects.
ROOTS:
Absorb water, stabilize soil,
prevent erosion and increase
soil permeability.
LEAVES,
TWIGS AND BRANCHES:
Absorb sound and intercept
erosion- causing rainfall.
LEAVES:
Remove pollutants from the
air, such as carbon dioxide and
particulate matter.
NCSG | Trees & Plants: Benefits to the Community | Fact Sheet 1
Sustainability Series
Quantifying Value
Most people have an inherent understanding that
vegetation provides both individual and community benefi ts.
In recent years, researchers and others have become better
at clarifying and quantifying the value of nature — especially
when it comes to trees. These include:
Air Quality
Plants produce the oxygen in the air people breathe.
A single mature tree can absorb as much as 48 pounds of
carbon dioxide per year and release enough oxygen into the
atmosphere to support two human beings.
Trees in parking lots help reduce hydrocarbon emissions
from cars by keeping temperatures of fuel delivery systems
cooler than what occurs in non- shaded lots. Both evaporative
emissions and exhaust emissions during the fi rst few minutes
of engine operation are reduced.
Water Resources and Stormwater
Two- thirds of the water supply in the United States
comes from precipitation fi ltered through forests. Healthy,
intact forest vegetation and soils help control water fl ows in
streams, including peak fl ows after storms, low fl ows during
dry weather, sediment levels, and water chemistry and
quality.
Up to 55 percent of the variation in water treatment
costs can be explained by the percent of forest cover in the
water source area.
Because forests act as water storage units, they can save
costs for stormwater management. One hundred large mature
trees intercept 1.2 million gallons of rainfall per year, and for
every 5 percent tree cover added to a community, stormwater
runoff is estimated to be reduced by approximately 2 percent.
Forests near Atlanta, Georgia, were estimated to save the
city $ 420 per acre per year in stormwater management costs
enrichment.
Land and Aquatic Resources
Loss of forest cover has been shown to lead to loss of
soil by wind and water. Loss of topsoil lowers the productivity
of agriculture and forest ecosystems, and impacts aquatic
ecosystems through sedimentation and nutrient enrichment.
Biodiversity
Native plant communities provide the food and shelter
needed to maintain biodiversity. The native fl owering
dogwood ( Cornus fl orida) supports 117 species of moths
and butterfl ies alone. These insects are food sources for
other animals, such as birds. Non- native ornamental plants
support 29 times fewer animals than do native ornamentals.
Energy Savings
Shade from two large trees on the west side of a house
and one on the east side can save up to 27 percent of a
typical residence’s annual air conditioning costs. Well-located
trees can also result in similar savings for government
buildings and businesses.
Good for Business
Urban trees improve economic stability for the retail
sector by attracting businesses and consumers. Customers
spend more time and shop more often in well- landscaped
business districts and are willing to pay up to 12 percent
more for goods and services.
One study suggest that landscape amenities have the
highest correlation with offi ce building occupancy rates —
higher even than direct access to arterial routes.
Shopping centers that have ample vegetation, like this one in
Wilmington, N. C., can increase patronage simply by providing a
pleasant location to visit. ( Photo: Pam Smith)
The national averages of revenues collected by
local governments for each dollar spent on com-munity
services for the land uses below are:
• Residential: $ 0.87
• Commercial/ Industrial: $ 3.45
• Farmland/ Forestland/ Open Space: $ 2.70
From a presentation by Jeffery Dorfman, University of
Georgia, Alliance for Quality Growth, August 17, 2004.
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NCSG | Trees & Plants: Benefits to the Community | Fact Sheet 1
Sustainability Series
Deferred Street Maintenance
Repaving can be deferred for as many as 10 years on a
well- shaded street and 25 years on a heavily shaded street.
Shading reduces the amount of oil that is volatilized ( changed
to a gaseous or vapor form) from the asphalt. Volatilization
leaves the stone aggregate unprotected and vehicles can
cause the asphalt to loosen and break down. Large shade
trees can also reduce costs of repaving by 58 percent over a
30- year period.
Property Values
Properties with trees are estimated to be valued 5 to
15 percent higher than comparable properties without trees.
Higher property values translate to increased tax revenues for
local governments.
Human Health and Community
Trees in public housing neighborhoods are linked to
lower levels of fear, contribute to less violent and aggressive
behavior, and encourage better neighbor relationships and
coping skills.
The presence of trees can also reduce mental fatigue,
help people relax and reduce aggression.
Hospital patients with views of trees have been found to
need less medication and have faster recovery times following
surgery.
Vegetation provides character and sense of place
to public spaces where community members gather and
recreate.
Climate Moderation
Large shade trees can reduce local temperatures by 5 to
10 degrees Fahrenheit.
Plants also utilize sunlight and carbon dioxide to produce
sugars and oxygen. Carbon dioxide is a known heat- trapping
gas that contributes to global climate change.
FORESTS AT A GLANCE
* North Carolina is one of six states where
future housing development on rural lands is
most likely to affect private forest cover.
* There are 18.6 million acres of forest land in
North Carolina, slightly more than 59 percent
of the state’s land area.
* Approximately 86.5 percent of forest land is
privately owned and 97 percent is classifi ed as
available or capable of timber production.
* The total economic value of North Carolina’s
forests, as estimated by the U. S. Forest Ser-vice,
is $ 30 billion dollars.
PLANTS LOWER TEMPERATURES
Vegetation helps moderate local temperatures
through evapotranspiration ( ET). As the name
implies, ET occurs as two processess. Evapo-ration
occurs on surfaces when liquid water
changes to water vapor ( vaporization). Tran-spiration
is simply vaporization through small
openings on a plant leaf ( stomata). In both
processes, solar radiation or heat is used to
change the water molecules from a liquid to a
vapor, contributing to lower temperatures.
Increases in residential and commercial development can be linked
to loss of forest health, decreases in native fi sh and wildlife and
their habitats, reduced opportunities for outdoor recreation, and
decreases in the production of timber and other forest products.
( Photo: Gloria Putnam/ North Carolina Sea Grant)
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NCSG | Trees & Plants: Benefits to the Community | Fact Sheet 1
Sustainability Series
Advances in Threat Assessment and their Application to
Forest and Rangeleand Management. General Technical
Report, Portland, OR, U. S. Department of Agriculuture, Forest
Service, Pacifi c Research Station.
• Tallamy, Douglas, “ A Call for Backyard Biodiversity,”
American Forests, Autumn 2009.
• Ulrich, R. S. ( 1985). “ Human Responses to Vegetation
and Landscapes.” Landscape and Urban Planning, 13, pp.
29– 44.
• Wolf, K. L. ( 1999). “ Nature and Commerce: Human Ecology
in Business Districts.” In C. Kollin, ed., Building Cities
of Green: Proceedings of the 1999 National Urban Forest
Conference. Washington, D. C.: American Forests, pp. 56– 59.
U. S. DEPARTMENT OF COMMERCE
NATIONAL OCEANICAND ATMOSPHERICADMINISTRATION
North Carolina Sea Grant
NC State University
1575 Varsity Dr., Varsity Research Bldg., Module 1
Campus Box 8605, Raleigh, NC 27695- 8605
Phone: 919/ 515- 2454
Other pieces in the Sustainability Series are available
at www. ncseagrant. org. For more information on spe-cifi
c topics, coastal communities should contact
Gloria Putnam of North Carolina Sea Grant at
gloria_ putnam@ ncsu. edu or 919/ 513- 0117.
UNC- SG- 10- 06A Autumn 2010
This document was developed with partial funding from the
NOAA Coastal Nonpoint Source Pollution Control Program
under Grant NA09NOS4190096.
PLANTS HELP BEAT THE HEAT
The lack of vegetation in a predominantly built
environment can create a heat island effect where
air and surface temperatures in urban areas are
higher than nearby rural areas with more vegeta-tion.
This difference can be as much as 2 to 10
degrees Fahrenheit and is usually most signifi cant
in the afternoon. In the built environment, solar
energy is absorbed by unshaded streets, walls
and other surfaces and released slowly back into
the atmosphere, warming the surrounding air.
Vegetation provides shade, thereby reducing heat
absorption and in combination with the soil, mod-erates
temperature through evapotranspiration.
( Graphic: Heat Island Group, Lawrence Berkeley
National Laboratory)
Information for this document was drawn from:
• American Forests. Urban Ecosystem Analysis, Atlanta Metro
Area: Calculating the Value of Nature, Washington, D. C.,
August 2001.
• Akbari, H., Davis, S., Dorsano, S., Huang, J., Winnett, S.
( eds.). ( 1992). Cooling Our Communities – A Guidebook
On Tree Planting and Light- Colored Surfacing. U. S.
Environmental Protection Agency, Offi ce of Policy Analysis,
Climate Change Division. Lawrence Berkeley National
Laboratory Report No. LBL- 31587.
• Arzamassova, E., Lerner, J., and Peterson, C. ( 2003).
The Economic Benefi ts of Urban/ Suburban Forestry. Brown
University Center for Environmental Studies.
• Colorado Tree Coalition. Benefi ts of Trees in Urban Areas.
Retrieved Nov. 16, 2010, from www. coloradotrees. org./
benefi ts. htm
• Caryn, Ernst, Land Conservaton and the Future of America’s
Drinking Water, Protecting the Source, The Trust for Public
Land and American Waterworks Association, 2004.
• Coder, Rim D., Identifi ed Benefi ts of Community Trees and
Forests, White Paper, University of Georgia, October 1996.
• Faber Taylor, A., Kuo, F. E., & Sullivan, W. C. ( 2001).
“ Coping with ADD: The Surprising Connection to Green Play
Settings.” Environment & Behavior, 33 ( 1), pp. 54– 77.
• International Council for Local Environmental Initiatives
– Local Governments for Sustainability. ( November
2006.) Talking Trees: An Urban Forestry Toolkit for Local
Governments.
• Kuo, F. E. ( 2003). “ The role of arboriculture in a healthy
social ecology.” Journal of Arboriculture, 29 ( 3), pp.
148– 155.
• North Carolina Department of Environment and Natural
Resources, Division of Forest Resources, 2008 Annual
Report, Managing and Protecting the Forest Resources of
North Carolina.
• Peper, P. J., McPherson, E. G., Simpson, J. R., Albers, S.,
Xiao, Q. ( 2010). Central Florida community tree guide:
benefi ts, costs, and strategic planting. Gen. Tech. Rep. PSW-GTR-
230. Albany, CA: U. S. Department of Agriculture, Forest
Service, Pacifi c Southwest Research Station.
• Stein, Susan M., Hatfi eld, Mark H., McRoberts, Ronald
E., Meneguzzo, Dacia M., Comas, Sara. ( 2010). Threats to
Private Forest Lands in the U. S. A.: A Forest on the Edge
Study, In Pye, J. M., Rauscher, H. M., Sands, Y., eds.
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