STATUS OF RIPARIAN ECOSYSTEMS IN THE UNITED STATES1

ABSTRACT: An attempt was made to review all available data on the extent and status of riparian ecosystems in the U.S.A. This report presents a synthesis of the findings, including some estimates of how much land was originally covered by woody riparian vegetation, and how much remains in that condition today. A synopsis of information is presented on the status of riparian ecosystems in each of 10 regions: California, Pacific Northwest, Rocky Mountain, Arid Southwest, Plains-Grasslands, Lake States, Corn Belt, Mississippi Delta, Northeast-Appalachian, and Southeast. Woody riparian plant communities once covered an estimated 75 to 100 million acres of land in the contiguous 48 states. Mankind has converted at least two-thirds of that nationwide acreage to other non-forest land uses and it is estimated that only 25 to 35 million acres of riparian plant communities remain in a near natural condition. Across the country, loss of riparian acreages is directly attributable to water resource development (especially channel modification and water impoundment), floodplain clearing for agriculture, and urbanization. In many states of the arid west, the midwest, and the lower Mississippi alluvial valley, riparian vegetation has been reduced in area by more than 80 percent. Riparian woodlands are one of this country's most heavily modified natural vegetation types.