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

Abstract

Historically, anthropogenic activities have contributed to the direct loss of wetland area, mostly due to agriculture and urban land uses. Urbanization also indirectly impacts wetlands at a landscape scale through altered wetland hydrology and change in the spatial configuration of wetlands in a watershed. In addition, beaver (Castor canadensis) create and modify wetlands in a landscape. Because of recent increases in urbanization and rising beaver populations, a raster-based geographic information system (GIS) was used 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 the study revealed that 29% of the land changed during the 41-year study period, and wetland conversion constituted 7% of the total change. The major reason for wetland loss was the construction of two large water-supply reservoirs in the watershed, and most of the remaining wetland loss was due to urbanization. Wetland functions vary depending on wetland type, and the results of this study showed that 90% of the change in wetlands from 1953 to 1994 was a result of shifting between wetland types. Beaver-modified wetlands increased 274%, and beaver activity was responsible for 23% of the wetland change.