Agenda - Planning Commission - 10/04/2012

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The Role of Tree Preservation rdinances in Green Infrastructure By Nancy Templeton, AICP, and David Rouse, AICP The premise of green infrastructure planning is that the vegetative elements of the landscape, including trees, shrubs, grass, etc., interact with other natural systems of air, water, and soil to protect and enhance ecosystem functionality within urban environments. Central to the concept of sustainable development and green infrastructure is that amenity and functionality come together to provide a "triple bottom line" of social, environmental, and economic benefits to people and the planet. While all vegetative elements, including open green spaces, are part of a community's green infrastructure network, urban forests arguably comprise the largest structural component of the network. Close to 8o percent of U.S. citizens live in urban areas. It is estimated that urban forests in the United States contain about 3.8 billion trees (Alig, Carr, Comas, Greenfield, Nowak, Randier, Stein, 2oio). As urban areas continue to expand across the country, communities will depend more and more on the benefits of the urban forest as the largest component of the green infrastructure network. Protecting and enhancing this valuable resource is critical as a growing body of research and planning in green infrastructure has quantified the social, environmental, and fiscal benefits of the urban forest. SOCIAL BENEFITS OF THE URBAN FOREST Research on the impacts of trees on public health, safety, social behavior, and com- munity interaction indicates that there are direct positive social influences from ex- posure to trees. For example, a 2001 study by Frances Kuo and William Sullivan of the University of Illinois compared the social behavior of low-income residents living in different parts of the Robert Taylor Homes public housing complex in Chicago. One part of the complex was planted with trees and other greenery, while the other had little or no landscaping. The study concluded that residents with views of trees and greenery from their homes experienced more social interaction with neighbors and less ag- gressive behavior toward their partners or children. + GREEN INFRASTRUCTURE Green infrastructure encompasses the naturally occurring and human -built features that manage stormwater, remove pollutants, conserve energy, and provide other ecological, cost-effective, and environmentally sustainable services (Vibrant Cities & Urban Forests Task Force 2011). •v URBAN FORESTRY Urban Forestry means the planning, establishment, protection, and management of trees and associated plants, individually, in small groups, or under forest conditions within cities, their suburbs, and towns (Cooperative Forestry Act 1978). Trees have also been recognized as positively influencing the academic perfor- mance of high school students based on research findings for "attention restoration" theory (Augustin and Cackowski-Campbell zoll). Attention restoration theory, devel- oped by the University of Michigan School of Natural Resources and Environment, sug- gests that exposure to natural environments, either visual or tactical, restores mental en- ergy and enhances concentration. Crime and public safety are additional social conditions impacted by trees. There has been some disagreement among scholars as to whether trees deter crime by attracting more people to an area and signifying community strength, or facilitate it by providing concealment for criminals. A study by a team of environmental re- searchers from the University of Vermont examined crime rates and tree canopy cov- erage over an area from inner city Baltimore to suburban Baltimore County. Although disparities were found primarily because of the diversity in scale from urban to sub- urban communities, the researchers found that "a io% increase in tree canopy was associated with a roughly 12% decrease in crime" (Troy, Grove, and O'Neil -Dunne 2oi2). In areas where high canopy coverage was also associated with high crime rates, it was found that poorly groomed and low- lying vegetation provided concealment for criminal activity. ENVIRONMENTAL BENEFITS OF THE URBAN FOREST The environmental benefits of urban forestry as a component of the green infrastructure network are well documented by federal agencies such as the U.S. Environmental Protection Agency and the U.S. Forest Service, as well as state departments of nat- ural resources, universities, and local utility and watershed organizations. According ZONINGPRACTICE 9.12 AMERICAN PLANNING ASSOCIATION I page 2