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ASSESSING THE ECOLOGICAL CONDITION OF WETLANDS AT THE CATCHMENT SCALE
Citation:
Whigham, D. F., D. E. Weller, A. D. Jacobs, T. E. Jordan, AND M E. Kentula. ASSESSING THE ECOLOGICAL CONDITION OF WETLANDS AT THE CATCHMENT SCALE. LANDSCHAP 20(2):99-111, (2003).
Description:
We describe an approach to assessing the ecological condition of two classes of wetlands in the Nanticoke River watershed, a subwatershed in the Chesapeake Bay drainage of North America. We used the hydrogeomorphic (HGM) approach to assess the ecological condition of wetlands along non-tidal streams (riverine class) and wetlands associated with poorly drained soils on interfluves (flats class). Sampling protocols developed by the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program were used to select a spatially unbiased sample of sites for field-based assessments. Statistical procedures were used to determine the relationship between data compiled in the field-based assessments and spatial data from remote sensing or other mapping efforts. We wanted to determine if available geographic data could be used to assess individual wetlands or the overall condition of wetlands in the watershed without having to do site-specific assessments based on field sampling. The HGM approach to wetlands assessment appears to be a useful methodology when it is applied in combination with a spatially unbiased method for selecting sampling sites. There were significant relationships between results of HGM assessments and mapped geographic data, but the strengths of the relationships were variable, demonstrating potential limitations to the use of mapped geographic data to assess wetlands condition in relatively flat landscapes such as those present in the Nanticoke River watershed. Future improvements in the resolution of GIS data, however, should result in better correlations between GIS-based assessments and field-based assessments of wetlands.