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management, as well as an ongoing commitment. Green Infrastructure's Origins Green infrastructure is a new term, but not a new idea. It has roots in plan- ning and conservation efforts that started 150 years ago. The concept evolved from two important prece- dents: (1) the linking of parks and other green spaces for the benefit of people, and (2) the linking of natural areas to benefit biodiversity and counter habi- tat fragmentation. In 1903, landscape architect Frederick Law Olmsted stated that, "no single pazk, no matter how large and how well designed, would provide the citizens with the beneficial influences of nature." Instead, parks needed "to be linked to one another and to sur- rounding residential neighborhoods."' This idea of ]inking pazks for the bene- fit ofpeople sparked the modem green- ways movement. Additionally, wildlife biologists and ecologists have long recognized that the best way to preserve biological di- versity and ecological processes is [o create an integrated conservation sys- tem to counter habitat fragmentation. Creating and restoring connections between parks, preserves and other important ecological azeas isa key con- cept for the science of conservation biology and the practice of ecosystem management. The President's Council on Sustain- able Development identified green in- frastmcture as one of five strategic az- eas that provide a comprehensive ap- proach for sustainable community development. The Council's 1999 re- port stated, "Green infrastmcture sttat- egies actively seek to understand, le- verage, and value the different ecologi- cal, social, and economic functions provided by namral systems in order to guide more efficient and sustainable land use and development patterns as well as protect ecosystems.."Z This re- port, along with innovative projects at the state, regional and local levels, has led to a rapid increase in the use of the term "green infrastructure" and the application of its concepts and values. The modern greenways movement also has influenced green infrastructure planning and implementation. Al- though green infrastructure and green- ways share a common origin, green infrastructure differs from greenways in a[ least three major ways: Ecology vs. Recreation-Green in- frastructure emphasizes ecology, not recreation. Bigger vs. Smaller-Green infra- structure includes large, ecologically important hubs, as well as key land- scape linkages. Framework for Growth-Green infrastructure can shape urban form and provide a framework for growth. It works best when the framework pre- identifies both ecologically significant lands and suitable development azeas. Why Do We Need to Plan and Protect Green Infrastructure? Land is being developed faster than ever. The accelerated consumption and fragmentation of open land is America's primary conservation chal- lenge. The following statistics illustrate the problem: According to the December 2000 update of the Natural Resource Con- servation Service's National Resources Inventory, over the 15-year period from 1982 to 1997, the total acreage of de- veloped land in the United States in- creased by 34 percent (25 million acres). From 1982 to 1992, land was converted at 1.4 million acres per year; from 1992 to 1997, land was converted at 2.2 million acres a year. This rate is more than 1.5 times the previous 10- year rate.3 The 1997 American Housing Survey conducted by the Census Bureau and HUD found that between 1993 and 1997, 2.3 million acres of open space were converted to new single-family. homes each year. Almost 90 percent of this conversion occurred where lots were one acre or larger. These lots were purchased by only 33 percent of new homebuyers.^ According to a July 2001 report by the Center on Urban & Metropolitan Policy at The Brookings Institution, "between 1982 and 1997, the amount of urbanized land in the United States increased by 47 percent... During this same period, the nation's population grew by only 17 percent (See Table 1~„5 In many major metropolitan azeas, green space is rapidly disappearing. The Atlanta metropolitan area has lost 25 percent of its tree cover since 1973, nearly 350,000 acres. This loss equals nearly 50 acres of trees every day.b From 1970 to 1990, metropolitan Chi- cago experienced a 35 percent increase in developed land, but a population increase of only four percent., Some of our most threatened ]ands are in ur- ban fringe counties, which produce nearly 80 percent ofAmerica's fruit and vegetables and more than half of its dairy products. Many coral communi- ties also are rapidly developing.s 'U.S. Hegian Change in Popalation Change in - , Urhanizad Land Midw¢st 7.06% 32.23% Northeast 6.91% 39.10% South 22.23% 59.61% Wesi 32.21% 48.94% U.S. 17.02% 47.14% Table I. Population Growth versus Land Development, 1981-1997. (From: !;,[Liam Fulton, Ralj Penda[[, Mai Nguyen and Alicia Flarr[san, Who Sprawls Most? How Growth Patterns Differ Across the U.S., The Brookings Institution, Survey Series, July 2001. AUTUMN 2002 RENEWABLE RESOURCES JOURNAL 13