Northern Prairie Wildlife Research Center
The refuge is situated in the Lake Dakota Plain within the James River lowland physiographic division (USDA 1993) (Fig 2). The area is characterized by an ancient lake plain, glacial uplands, and alluvial flood plains.
|Figure 1. The Sand Lake study area, Brown County, South Dakota.||Figure 2. Physiographic divisions of eastern South Dakota (Johnson et al. 1995).|
The refuge is bisected into west and east halves by the James River and can be considered an isolated riverine landscape in an agricultural setting. Its 8,704 hectares are a mosaic of different land uses. Primary habitat types (n = 4) include:
Soil composition is strikingly different within and adjacent to the refuge. On the east side, the soils are characteristically sandy and loamy, similar to the Lake Dakota Plain. On the west side, soils are silty and sodium affected (USDA 1993). The soil types on either side of the refuge may enhance or restrict vegetation composition and faunal associations.
Of land adjacent to the refuge, 71% is intensively farmed cropland, 16.7% is permanent pasture, and 11.7% is idled land (Conservation Reserve Program) (Naugle et al. 1994).
Large seasonal fluctuations of climate are the rule rather than the exception in the region. Cold winters and hot, dry summers are common. Precipitation averages 44.6 cm annually, but cycles of drought and heavy precipitation are evident (USDA 1993). Mean annual temperature is 10.0° C (Spuhler et al. 1971).