The trees in our parks, yards, public spaces and streetscapes — our “urban forests” — play a vital role in the health and economic vitality of our communities. Trees affect the quality of the air and water where we live, the cost of heating and cooling our homes and businesses, property values, and ultimately, the safety and desirability of our neighborhoods and downtowns.

Unfortunately, in recent years urban trees have fallen victim to “downsizing” in the face of shrinking municipal budgets. Aging trees are removed but not replaced, while new plantings are restricted to small trees to save on maintenance costs. While this strategy may produce some short-term savings, it fails to take into account the broader and long-term benefits that residents, businesses and community visitors seek – clean air, clean water, and safe and attractive places.

The many benefits of urban trees and forest cover are highlighted in this fact sheet prepared by CivicWell (formerly the Local Government Commission). This fact sheet will help local officials, their staff and other community leaders understand and communicate the value of urban trees.

“Livable Communities and Urban Forests” Fact sheet
Download PDF: English Version | Spanish Version

Development of this fact sheet was supported by the USDA Forest Service Urban and Community Forestry Program on the recommendation of the National Urban and Community Advisory Council.

Livable Communities and Urban Forests

The trees in our parks, yards, public spaces and streetscapes – our “urban forests” – play a vital role in the health and economic vitality of our communities. Trees affect the quality of the air and water where we live, the cost of heating and cooling our homes and businesses, property values, and ultimately, the safety and desirability of our neighborhoods and downtowns.

Unfortunately, in recent years urban trees have fallen victim to “downsizing” in the face of shrinking municipal budgets. Aging trees are removed but not replaced, while new plantings are restricted to small trees to save on maintenance costs. While this strategy may produce some short-term savings, it fails to take into account the broader and long-term benefits that residents, businesses and community visitors seek – clean air, clean water, and safe and attractive places.

Are trees worth the cost?

Studies have shown that urban trees provide benefits worth many times the cost of their planting and upkeep. Indeed, in most areas of the country, communities can care for their largest trees for as little as $13 per tree per year, according to the Center for Urban Forest Research. And each tree returns an average of $65 in energy savings, cleaner air, better managed stormwater, extended life of streets (shaded streets require resurfacing less often), and higher property values. [1]

Economic Development

Trees stimulate downtown business

Trees help merchants enjoy greater sales and cities reap greater tax revenues. University of Washington
studies found that consumers will shop more often and longer in downtown business districts with street
trees and other landscaping than in districts without; and they are willing to pay more for parking and up to 11% more for goods and services. [2]

Trees influence residential property values

Developers can maximize profits by retaining existing trees and replanting trees following construction. Research comparing residential sale prices show that people are willing to pay 3-7% more for properties with ample trees versus those with few or no trees.

According to one of the most comprehensive studies of the influence of trees on residential property, an
analysis of prices in one city found that each large front yard tree added about 1% to a home’s resale value and an estimated increase of $100,000 (1978 dollars) in property tax revenues. [4]

Trees and healthy communities

Environmental Benefits

Trees improve climate and save energy

Rapid urbanization during the past 50 years has been associated with increases in downtown temperatures of nearly 1° F per decade – largely due to the increase in exposed heat-absorbing surfaces, such as dark rooftops, parking lots and streets.

As temperatures increase, energy demand for cooling increases, as do carbon dioxide emissions (a heat-trapping gas that causes global warming) from fossil-fuel power plants, municipal water demand, unhealthy smog levels, and human discomfort and disease. [5]

Neighborhoods with well-shaded streets can be up to 10° F cooler than neighborhoods without street trees. Three well-placed trees around a home can lower air conditioning bills by up to 30%, and windbreak trees can save up to 25% on winter heating costs. [6]

Trees clean the air

Trees remove pollutants from the air. They store carbon dioxide in their leaves, branches, trunks and roots. They absorb sulfur dioxide and nitrogen oxide, two major components of acid rain and ozone pollution. They intercept particulate matter, such as dust, ash, pollen and smoke, while releasing oxygen into the air through photosynthesis.

Research shows that 100 trees can remove five tons of carbon dioxide from the atmosphere per year, and can remove about 1,000 pounds of pollutants per year, including 400 pounds of ozone and 300 pounds of particulates. [7]

Trees prevent erosion and reduce runoff

Tree roots hold soil in place while tree canopies reduce the force of falling raindrops on barren surfaces – which prevent erosion. Trees also catch and hold rainfall – both of which can delay runoff and reduce flooding. Root growth and decomposition enable the ground to absorb more water, which also reduces flooding and helps replenish groundwater, a critical water source for many communities. Studies that have simulated urban forest effects on stormwater report annual runoff reductions of 2-7%. [9]

Public Health and Safety

Trees calm traffic and encourage walking

A treeless street can encourage higher speeds, increasing the frequency and severity of accidents.

Street trees provide both visual interest and obstacles near the road edge, which encourage safe speeds and quieter neighborhoods. Closely spaced trees help motorists gauge and control their speeds. Narrower
streets combined with street trees also slow drivers down, while maximizing shading of heat-absorbing asphalt. Trees planted between the curb and sidewalk improve safety by adding a buffer between moving vehicles and pedestrians.

Trees reduce crime and increase social ties

Trees can play an important role in reducing crime rates and domestic violence. In a study of Chicago public housing residents, University of Illinois researchers found that buildings with high levels of greenery had 52% fewer property and violent crimes than apartment buildings with little or no vegetation.

Why? Green spaces draw people outdoors, increasing surveillance and discouraging illegal activity. The green and groomed appearance of an apartment building is a signal that owners and residents care about a property, and watch over it and each other.

Greener common areas also facilitated stronger social ties.The more trees and grass in the common spaces,
the more those spaces were used by residents. Those living closer to green spaces enjoyed more social activities, had more visitors, knew more of their neighbors, and reported committing fewer acts of aggression toward household members than those living near barren spaces. [11]

Other health benefits

• Noise can reach unhealthy levels in cities. Trees reduce noise pollution by acting as a buffer and absorbing urban noise, especially high-frequency sounds that are the most distressing to people.
• Trees reduce exposure to ultraviolet light from the sun, lowering the risk of skin cancer and cataracts.
• Research indicates that views of nature reduce the stress response of both body and mind when stressors of urban conditions are present, reducing aggression and increasing calm.
• Hospital patients with a view of trees have been shown to need less medication and have faster recovery times following surgery. [12]

What local governments can do for urban greening

• Require shade trees in new development.
• Require shade trees in parking lots.
• Retrofit streets with trees along street edges and in medians.
• Encourage residents and businesses to plant shade trees on private property.
• Adopt a tree preservation ordinance.
• Hire or appoint a City forester/arborist.
• Conduct a street tree inventory and establish and fund a maintenance program.
• Count trees as a public utility capital asset.
• Use tree planting to strengthen communities and increase resident involvement.
• Collaborate with local community groups and tree organizations.

References

1. The Large Tree Argument: The Case for Large-Stature Trees vs. Small-Stature Trees, Center for Urban Forest Research and Southern Center for Urban Forestry Research and Information, U.S. Forest Service, 2004.
2. Fact Sheets #5 and #17, Center for Urban Horticulture, University of Washington.
3. “Greening Up Fertilizes Home Prices, Study Says,” Philadelphia Inquirer, Anthony S.Twyman, Jan. 10, 2005; “Wharton School Study Finds Greening  Good Investment,” The Pennsylvania Horticultural Society, November 2004.
4. Tree Guidelines for Inland Empire Communities, E.G. McPherson et.al., Local Government Commission, 2001.
5. Ibid.
6. “Potential of Tree Shade for Reducing Residential Energy Use in California,” Journal of Arboriculture, J.R. Simpson and E.G. McPherson, 22: 1, 1996;“Energy Savings With Trees.” Journal of Arboriculture, G.M. Heisler, 12:113-125, 1986.
7. Tree Guidelines for San Joaquin Valley Communities, E. G. McPherson et.al., Local Government Commission, 1999.
8. Tree Guidelines for Inland Empire Communities, E. G. McPherson et.al.
9. Ibid.
10. “Using Nature’s Plumbing to Restore Aquatic Ecosystems: The City of Seattle’s Natural Drainage System,” James N. Levitt and Lydia K. Bergen, The Report on Conservation Innovation, Fall, 2004.
11. Human – Environment Research Laboratory, University of Illinois at Urbana Champaign.
12. Tree Guidelines for Inland Empire Communities, E. G. McPherson et.al.