HABITAT QUALITY AND ITS RELATIONSHIP TO LANDSCAPE PATTERN IN EXURBANIZING WATERSHEDS OF SOUTHEASTERN MICHIGAN.

D.M. Infante and J.D. Allan. School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, U.S.A., 48109

Although stream habitat often is viewed as the connecting link between land use and stream biota, few studies directly examine this relationship. We derived landscape data for approximately 50 study catchments and from 200 m–wide buffers in southeastern Michigan to obtain measures of land use, geology, and a number of fragmentation statistics. Habitat assessment resulted in a total of 76 variables in 4 categories: channel shape, substrate, channel units, and visual habitat metrics. We used correlation matrices to reduce the number of variables and PCA to identify three axes based on 19 variables that explained 68% of the variation in habitat among sites. Axis one described variation in visual habitat and substrate, axis two described low flow variability, and axis three described channel morphology. Using multiple linear regression to predict habitat from landscape measures, we found that channel shape and substrate were best predicted by landscape data derived from the entire catchment. Visual habitat metrics, however, were best predicted by the land use within the stream buffer and from landscape fragmentation statistics. Our results demonstrate that the linkage between measures of landscape and instream habitat may be apparent at either reach or catchment scale, depending upon the variables of interest.