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THE ROLE OF WATERSHED CLASSIFICATION IN DIAGNOSING CAUSES OF BIOLOGICAL IMPAIRMENT
Citation:
Detenbeck, N E., V. J. Brady, J. C. Brazner, M F. Moffett, V M. Snarski, AND J A. Thompson. THE ROLE OF WATERSHED CLASSIFICATION IN DIAGNOSING CAUSES OF BIOLOGICAL IMPAIRMENT. Presented at US EPA/NSF/USDA Water and Watersheds Program Review, San Francisco, CA, April 17-19, 2001.
Description:
We compared classification schemes based on watershed storage (wetland + lake area/watershed area) and forest fragmention with a gewographically-based classification scheme for two case studies involving 1) Lake Superior tributaries and 2) watersheds of riverine coastal wetlands on Lake Michigan. Main and interactive effects of watershed storage and forest fragmentation on watershed exports, habitat quality, community composition and food-web relationships were compared within and across two hydrogeomorphic regions within the Northern Lakes and Forest Ecoregion. In 1997-1998, 24 second-order stream watersheds were selected to establish a 3-way factorial design. In 1998-1999, third order watersheds in high and low fragmentation classes were selected along gradients of watershed storage within each region. Hydrologic regimes and both baseflow and snowmelt water quality in second-order streams of the western Lake Superior basin were affected by regional influences, storage, and fragmentation. For third-order streams, significant effects of storage, fragmentation, and fragmentation by storage interactions were more frequent, while region by watershed interactions were relatively rare. Use of a stratified random sampling scheme for stream water quality based on both region and watershed attributes improved assessments of reference condition, differences in regional sensitivity and potential causes of impairment.