Urban trees are dispersed in small clusters throughout a city, but have a collective impact on both the environment and human health. Increasing the amount of urban trees—and the amount of mature, leafy canopy that spreads across the city—improves the overall quality of life for urban residents and saves money, too. Some examples include:
- Water quality: Trees absorb rain in their leaves and roots, reducing stormwater runoff, erosion and flooding. Trees also filter nutrients and sediments from rainwater, reducing pollution to local waterways. When too few trees remain, communities increasingly rely on costly engineered solutions to manage stormwater and reduce pollution.
- Air Quality: Trees filter pollutants carried in the air that affect both local rivers and human lungs. Trees are especially effective at storing carbon, which helps to reduce global warming. They also remove particles of dust, smoke and ash, as well sulfur dioxide and nitrogen oxides, two major components of acid rain.
- Energy Savings: Trees are natural insulators that cool buildings during the summer and keep them warm during the winter. Homes with well-placed trees cut energy costs by as much as 25 percent.
- Temperature Control: Trees take a bite out of the urban heat island, where buildings, paved surfaces, and automobile engines create air temperatures that are 2 to 10 degrees hotter than rural communities.
- Wildlife Habitat: Urban trees offer refuge for mammals, insects and birds, including migratory species. Along streams, they support fish and amphibian habitat by cooling the water and creating shelter and feeding grounds along fallen branches and leaves.
- Recreation: In urban areas, wooded areas are valuable settings for recreation and exercise, which is especially important when 75 percent of Americans aren’t getting the exercise they need.
- Quality of Life: Urban settings filled with trees foster human connections to the environment and to one another by reducing stress, increasing the use of public spaces and offering healthier play for children. Studies have also indicated that work productivity and patient recovery are aided by a green environment. Drivers tend to be less aggressive on tree-lined thoroughfares, while consumers linger longer and spend more money. Homes with mature trees can sell for at least 7 percent more than those without. And, a Baltimore study showed that more than half of a neighborhood’s residents consider moving away when tree cover falls below 15 percent.
Sources include “The State of Chesapeake Forests,” published in 2006 by The Conservation Fund.