Human- and beaver-induced wetland changes in the Chickahominy River watershed from 1953 to 1994

Historically, anthropogenic activities have contributed to the direct loss of wetland area, mostly due to agriculture and urban land uses. Urbanizatio n also indirectly impacts wetlands at a landscape scale through altered wet land hydrology and change in the spatial configuration of wetlands in a wat ershed. In addition., beaver (Castor canadensis) create and modify wetlands in a landscape. Because of recent increases in urbanization and rising bea ver populations, a raster-based geographic information system (GIS) was use d to analyze the combined effects of humans and beavers on wetland area and types in the Chickahominy River watershed from 1953 to 1994. Results of th e study revealed that 29% of the land changed during the 41-year study peri od, and wetland conversion constituted 7% of the total change. The major re ason for wetland loss was the construction of two large water-supply reserv oirs in the watershed, and most of the remaining wetland loss was due to ur banization. Wetland functions vary depending on wetland type, and the resul ts of this study showed that 90% of the change in wetlands from 1953 to 199 4 was a result of shifting between wetland types. Beaver-modified wetlands increased 274%, and beaver activity was responsible for 23% of the wetland change.