Global Problems, Local Solutions: Measuring the Value of the Urban Forest

Article excerpt

Farsighted and chronically green people have always known that the urban ecosystem provides multiple benefits to denizens of the world's teeming population centers. But to engineers, developers, and urban leaders, natural features often appeared to be impediments to progress. When trees were added back to the urban landscape - after development - they were seen as a soft benefit and an expense.

It has taken 20 years of research and the very recent application of high-speed computer mapping technology to begin to provide accurate and quantifiable information on the hard economic and ecological benefits of trees and forests in urban areas.

However, the impact of these new scientific findings would not be nearly as significant without the even more recent explosion of creative ways that ecologists, foresters, planners, and others are combining aerial photography with satellite images, ecological research, and computer technology for easy-to-use, cost-effective local applications. The coming together of the science and its popular application means that a whole new database of urban ecological and economic information is coming on-line. Using this information will be like opening an important new window on the urban environment.

In the forefront of the application of computer mapping and analysis to community environments is a system developed by AMERICAN FORESTS to demonstrate urban forests' hard-dollar value to their communities. At the heart of the system is a software package called CITYgreen, which uses Geographic Information Systems (GIS) software and sophisticated computerized mapping techniques to measure, map, and analyze urban ecosystems. Cutting-edge scientific findings about the functional values of natural resources are then applied to calculate the financial contribution of the urban forest and natural resources. The software provides the framework to convert natural resource values into public policy concerns by analyzing three key areas: energy conservation, stormwater, and air pollution abatement. The resulting Urban Ecological Analysis looks at the entire ecosystem, making it part of the planning process without pitting development against the environment. According to AMERICAN FORESTS' vice president Gary Moll, "When urban forests are viewed for their role in larger ecosystems, a wide range of values and benefits can be connected to them."

Population growth may not be this year's sexy environmental issue, but the increasing concentration of humanity in urban centers around the globe is creating many of the major crises facing us, and that includes crises in how we manage our natural resources to comply with federal, state, and local environmental laws. Urban populations are growing two and a half times faster than their rural counterpart. Today, almost 50 percent of the world's population lives in cities; by the year 2025, more than two-thirds will inhabit cities.

The 1992 United Nations Conference on Environment and Development, held in Rio de Janeiro, set a goal of sustaining economic growth while maintaining the essential integrity of the earth's ecosystems. The Conference recognized that while world leaders and national governments could support sustainable development, implementation would necessarily occur at the local and regional levels. Rene DeBois' philosophy of "Think globally; Act locally," a popular bumpersticker, says it all.

William E. Rees of the University of British Columbia has questioned whether the remaining stocks of natural capital are adequate to sustain the anticipated lead of the human economy into the next century. In the book Population and Environment, he defines the "ecological footprint" as "the corresponding area of productive land and aquatic cosystems required to produce the resources used, and to assimilate the wastes produced, by a defined population at a specified material standard of living, wherever on Earth that land may be located. …