Conservation and management issues and applications in population viability analysis [Exercise 15]

Abstract

The western prairie fringed orchid is dependent on wetland habitat (U.S. Fish and Wildlife Service 1996). Prairie wetlands in which the orchid has historically thrived are usually ephemeral, filling with water in wet years and drying up during droughts. Wetland abundance and persistence is a function not only of variations in annual precipitation, but also of changes in groundwater levels beneath the prairie surface. The U.S. Fish and Wildlife Service makes this relationship explicit in its definition of wetlands by stating that "wetlands are lands transitional between terrestrial and aquatic systems where the water table (i.e., groundwater) is at or near the surface. . ." (Cowardin et al. 1979). Thus, in addition to having soil moisture relatively near the surface, the number, extent, and depth of prairie wetlands is strongly affected by the amount of groundwater present in deeper, more permanent reservoirs known as aquifers. During periods of high precipitation, some water falling or melting on the surface of a landscape percolates through the soil and reaches the groundwater, causing the water table to rise closer to the surface, and contributing to greater extent and persistence of wetlands. During dry periods, or when groundwater is removed from the aquifer directly by human activities, the level of the water table is lowered.

Citation

Sieg, Carolyn Hull; King, Rudy M.; Van Dyke, Fred. 2003. Conservation and management issues and applications in population viability analysis [Exercise 15]. In: Van Dyke, Fred, ed. A Workbook In Conservation: Solving Practical Problems in Conservation. New York, NY: McGraw-Hill. p. 115-122.