REASONS TO SAVE OUR CANOPY
Canopy Trees provide cleaner air for communities.
The leaves in the tree canopy filter out pollutants, dust, and
small micro metals while taking in carbon dioxide and releasing oxygen.
A healthy tree canopy will reduce smog and general air
pollution, while filtering ozone, nitrogen oxides, ammonia and sulfur
TREE EXAMPLE: A tree can grow to manufacture five pounds of pure
oxygen per day, consume carbon dioxide to fight the "greenhouse effect"
that threatens our survival, and provide the cooling
equivalent of ten room-size air conditioning units.
TREE EXAMPLE: A major study of Chicago estimated that trees in that
city annually removed 15 metric tons of carbon monoxide, 84 tons of
sulfur dioxide, 89 tons of nitrogen dioxide, 191 tons of
ozone, and 212 tons of small particulates. The estimated value of this
pollution removal was $1 million for trees in the city itself and $9.2
million for the entire Chicago area (Nowak, 1994).
TREE VALUE: A tree, over a 50-year period, will generate $31,250
worth of oxygen, provide $62,000 worth of air pollution control, and
recycle $37,500 worth of water. (The National Arbor Day Foundation)
- Forty trees remove 80 pounds of air pollutants annually.
- Four million trees can save $20 million in air pollution clean up.
- Four hundred trees capture 140,000 gallons of rainwater annually.
- Four million trees save $14 million dollars in annual storm water runoff costs.
- One acre of forest absorbs six tons of carbon dioxide and puts out
four tons of oxygen. This is enough to meet the annual needs of 18
people. (U.S. Department of Agriculture)
Canopy Trees provide cooler air for houses and buildings.
A healthy tree canopy can provide a ten-degree reduction in surface temperature, cooling the surrounding landscape and grounds.
TREE EXAMPLE: The ambient air temperature difference between an
urban heat island and a vegetated area can be as much as 2-10 degrees F.
The temperature measured directly above
fabricated surfaces can be as much as 25 degrees F hotter than the air
temperature beneath a forested area. (Akbari et. al., 1992; Simpson and
TREE EXAMPLE: Computer simulations using standard building and tree
configurations for cities across the U.S. indicate that shade from a
single well-placed, mature tree (about 25-ft crown
diameter) reduces annual air conditioning use 2 to 8 percent and peak
cooling demand 2 to 10 percent. (Simpson and McPherson, 1996)
TREE EXAMPLE: Trees properly placed around buildings can reduce air
conditioning needs by 30 percent and can save 20 to 50 percent in energy
used for heating. (USDA Forest Service)
- Shade from trees could save up to $175 per year (per structure) in air conditioning costs. (Dr. Lowell Ponte)
- The net cooling effect of a young, healthy tree is equivalent to
ten room-size air conditioners operating 20 hours a day. (U.S.
Department of Agriculture)
- Four trees planted around a home can save up to 30% on summer cooling costs.
- One million trees save $10 million a year in energy costs.
Canopy Trees improve local water quality.
The healthy tree canopy of native urban parks and forests, when
maintained, will strongly influence the local water quality of streams
and run-off. The forest and park tree canopy and secure root
systems will slow and reduce storm water runoff, thus easing flooding
and holding back erosion.
The native trees with strong canopies will assist in filtering water
runoff, helping to slow and reduce sources of water pollution in local
TREE EXAMPLE: In Milwaukee, where urban trees cover about 16 per cent
of the city, trees reduce storm water flows by 22 per cent. The city
saves an estimated $15.4 million by avoiding the
construction of additional retention capacity. (MacDonald, 1996)
TREE VALUE: In Austin, heavy rains make storm water management a
priority issue. Austin's tree canopy almost twice that of Milwaukee's,
reduced storm water flow by
28 per cent, providing the city with an estimated $122 million in
savings. (MacDonald, 1996)
The planting of trees means improved water quality, resulting in less
runoff and erosion. This allows more recharging of the ground water
supply. Wooded areas help prevent the transport of sediment
and chemicals into streams. (USDA Forest Service)
Canopy Trees save energy.
Trees cool the air naturally in two ways: through water evaporating from the leaves and direct shade.
Homes shaded by trees need less energy for cooling which means lower monthly utility
bills in summer and a reduced need for utilities to increase power generation
to meet peak load demand, reducing brown outs.
- A study of urban forests in Modesto, California shows that for each
$1 invested in urban forest management, $1.89 in benefits is returned
to residents. City trees actually remove 154 tons of air
pollutants, increase property values by over $1.5 million, and provide
shade that saves over $1 million. This information convinced city
officials to increase the tree budget and an electric utility
company to invest $20,000 in developing the Modesto Tree Foundation. (Modesto Tree Foundation)
- There are about 60-to 200- million spaces along average city streets where trees could be planted.
This translates to the potential to absorb 33 million more tons of
CO2 every year, and saving $4 billion in energy costs. (National
Canopy Trees are good for business.
A series of studies has investigated associations between the urban
forest and people’s response to shopping settings. Scientific results
suggest that having trees in the business district streetscape is
an important investment for a business community. The presence of a
quality urban forest positively influences shoppers' perceptions, and
probably, their behavior.
Canopy Trees can be a stimulus to economic development, attracting new business and tourism.
Commercial retail areas are more attractive to shoppers, apartments
rent more quickly, tenants stay longer, and space in a wooded setting is
more valuable to sell or rent. (The National Arbor Day
Canopy Trees raise real estate value.
Shaded neighborhoods and well-landscaped yards have a positive
economic influence on real estate values, timeliness of house sales and
neighborhood desirability. Studies report that landscaping
speeds the sale of a home by four to six weeks. (www.sactree.com)
Canopy Trees help stop inner city violence.
A scientific study by the Human-Environment Research Lab has
demonstrated that contact with nature may actually help reduce the
incidence of aggression and violence in inner-city
neighborhoods. According to this study, levels of aggression were
significantly lower among people who had some kind of nature outside of
their apartments versus those who didn't. The impact of the
physical environment on human aggression has been well established -
crowding, high temperatures, and noise have all been linked to violent
behavior. Some scientists believe that it's
because people living under these conditions suffer from something
called chronic mental fatigue, which can make them inattentive,
irritable, and impulsive - all of which can be linked to aggressive
behavior. Exposure to green spaces, it has been shown, can mitigate the
harmful effects of chronic mental fatigue, reducing aggressive behavior
in the process.
In laboratory research, visual exposure to settings with trees has
produced significant recovery from stress within five minutes, as
indicated by changes in blood pressure and muscle tension. (Dr.
Roger S. Ulrich Texas A&M University)
Urban and Rural Canopy Tree Values
A tree can return up to $2.70 for each $1 on community
investment…that’s a 270% return. (based on a 40-year average life span
according to Center for Urban Forest Research, Pacific Southwest
Research Station, U.S. Forest Service, Davis, CA)
- Trees in commercial parking lots induce shoppers to spend 11% more for goods and services. (www.sactree.com)
- Trees can boost the market value of your home by an average of 6 or 7 percent. (Dr. Lowell Ponte)
- Healthy, mature trees add an average of 10 percent to a property's value. (USDA Forest Service)
- Landscaping, especially with trees, can increase property values as much as 20 percent. (Management Information Services/ICMA)
- Nationally, the 60 million street trees have an average value of $525 per tree. (Management Information Services)
- Studies at the city of Davis, California utilized existing data on
the benefits and costs of municipal trees applied to the results of a
sample inventory of the city’s public and private street trees. Results
indicate that Davis maintained nearly 24,000 public street trees that
provided $1.2 million in net annual environmental and property value
benefits, with a benefit–cost ratio of 3.8:1. (Maco and McPherson, 2003)
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