Want to see a break down of the specific ecosystem services trees provide Pittsburgh residents?  Read the entire STRATUM report here.

Trees are a critical element for a livable urban environment.  Publicly owned trees - and, collectively our urban forest, provide a wide range of health and safety, social, economic, and environmental benefits as essential to the vitality of a city as any other component of community infrastructure.  Like streets, sidewalks, public buildings, and recreational facilities, trees are a major capital asset.

Trees are an asset that gains value as they mature.  To reach this maturity level, trees must be maintained.

The City of Pittsburgh Street Tree Inventory data establshes a basis for a complete cost-benefit analysis of Pittsburgh's street tree program using STRATUM software recently developed by the US Forest Service.  The analysis provides a dollar value indication of the environmental work provided by each tree. 

According to the US Forest Service, as trees grow larger their ability to provide environmental services and benefits increases dramatically.  Forest Service researcher David Nowak has stated, "a big tree does 60 to 70 times the pollution removal of a small tree." 

Preliminary results of Pittsburgh's forthcoming STRATUM study shows that every dollar we invest in planting and maintaining our street trees provides four dollars in benefits.

Cleaner Air Quality

The American Lung Association's 2007 "State of the Air" report lists the Pittsburgh area as the second-most polluted metropolitan area in America, behind only the Los Angeles metropolitan area.  According to a June 26, 2006 article in the Post Gazette, Pittsburgh had 121 bad air-quality days of 305 total days measured, which put it near the bottom of the list of cities.   Compare that with Honolulu, which had but three bad days of 174 days measured in 2005.  Pittsburgh also had seven days in 2005 when its air was too unhealthy to breathe. Compare that with smog-capital Los Angeles, which had 10 unhealthy days.

The rankings are based on the ozone pollution levels produced when heat and sunlight come into contact with pollutants from power plants, cars, refineries and other sources.  Air pollution threatens human health, keeping children and teachers out of school, and increases emergency room visits and health care costs.

Leaves filter the air we breathe by removing dust and other particulates. Leaves absorb carbon dioxide and other pollutants from the air such as ozone, carbon monoxide, and sulfur dioxide.  In exchange, trees give off vital oxygen. 

Cleaner Water and Less Polluted Runoff

Cooling Cities

According to a report released in July, 2007 by the Union of Concerned Scientists, average temperatures across the Northeast have risen more than 1.5 degrees Farenheit since 1970.  We feel this in Pittsburgh with an increase in 90+ degree days throughout the summer months.  This intense heat leads to health problems and increased energy costs due to the greater demand for air conditioning. 

Trees help to alleviate the effects of the heat by providing shade over our homes, streets, parking lots, and parks.  In addition to providing shade, trees emit water vapor that cools hot air.This in effect slows climate change.

By lowering temperatures, urban trees reduce our energy consumption and decrease power plant emissions that contribute to climate change. Urban trees also use photosynthesis to rid the atmosphere of carbon dioxide, the primary gas responsible for global warming.

Enhanced Community Life

Neighborhood trees enhance community life.  Offering rest and recreation. trees create natural places for children to play, to relax, or talk with neighbors.

Trees support wildlife. Many birds, small animals, and insects rely on trees for food and shelter.  Wildlife offers additional character to communities and provides learning opportunities for our younsters.

Trees improve the view. Trees help to soften the impact of the manufactured environment and poor development. Trees screen unsightly areas and add beauty throughout our community.

Reduced Crime and Anxiety

Trees lower stress by buffering traffic noise and cooling hot temperatures.  As residents are attracted to safer, more inviting neighborhoods, they are more likely to socialize where they live, and to feel a greater sense of connection to their community. More eyes on the streets and other public spaces results in lower crime rates.

Trees provide a soothing and harmonious environment that reduces blood pressure and speeds healing. Studies show that hospital patients recover faster when they have a view of trees.

Trees make communities safer. They calm traffic and frayed nerves, reduce driver stress and the number and severity of auto accidents. Trees planted along the street enhance pedestrian safety and encourage walking by providing a natural, physical barrier between traffic and sidewalk.

Increased Economic Growth

With many direct economic benefits, trees are an asset.  Trees help to lower energy bills by providing shade for buildings in the summer and blocking cold wind in the winter.  Trees increase property value.  According to a University of Pennsylvania study, planting trees within 50 feet of houses in the Kensington area of Philadelphia increased home prices by 9%.   According to the Arbor Day Foundation, 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.