What is the area of the six major ecosystem types?
Grasslands and shrublands and forests each occupy about a third of the area of the lower 48 states, and farmlands about a quarter. The area of forest and grasslands and shrublands has declined since European settlement, as has the area of freshwater wetlands, and the extent of cropland and urban and suburban areas has grown. More recent trends show decline in forest, croplands, grassland and shrublands, and freshwater wetlands, and increases in urban and suburban areas (Table 4.1). The area of ecosystems is a very basic characteristic but, for various reasons, is complex to report. The main reason is that the area of different ecosystems is often tallied by different agencies, using different methods and definitions of the systems. Satellite remote sensing, which can provide an integrated view, is available at the appropriate scale for only one time period (1992) and thus cannot provide information on changes in the area of different ecosystems.Table 4.1 presents estimates from multipl
