Thursday, June 7, 2007 - 10:45 AM
397

Evaluating the response of instream habitat, water quality and macroinvertebrate assemblages, to riparian forest harvest in northern Minnesota

Dickson M. Atuke1, Raymond M. Newman1, and Bruce Vondracek2. (1) Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, 1980 Folwell Avenue, 200 Hodson Hall, St. Paul, MN 55108, (2) USGS, Minnesota Cooperative Fish and Wildlife Research Unit, 200 Hodson Hall, 1980 Folwell Ave, St Paul, MN 55108

We evaluated the effects of riparian forest harvest, along eight, northern Minnesota streams, on instream habitat, water quality and macroinvertebrate assemblages. The study was part of a larger project that included vegetation regeneration, fish and bird monitoring. Our design paired streams with a medium residual basal area (RBA) and a low RBA treatment. At each stream, we established treatment plots (riparian harvest, upland clearcut), control plots (no riparian harvest, upland clearcut), and reference plots (no riparian harvest, no upland harvest).  We sampled below, within and upstream of all plots.  Preharvest (2003) and postharvest (2004 – 2006) data were collected across 57 reaches. Benthic macroinvertebrates were assessed following the US EPA family-level composited, multi-habitat rapid bioassessment protocol. Stream habitat was evaluated with a Quantitative Habitat Evaluation Index (QHEI) modified from the Minnesota Pollution Control Agency’s habitat assessment protocol. Significant variation (p<0.05) in macroinvertebrate density, taxon richess, diversity and evenness was observed across sites and years, likely because of variability in flow regime and treatment effect. Significant variation was also observed for QHEI and water quality. However, because of large year-to-year variation, further monitoring may be required to definitively confirm whether the variation can be attributed to riparian forest harvest.

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