Author: Charles H. Frady

Publisher:

Published: 2005

Total Pages: 194

ISBN-13:

Recent studies of headwater streams have demonstrated their importance to overall watershed biodiversity, nutrient cycling, and energy flux. However, little attention has been paid to long-term effects of forest harvest on macroinvertebrate communities in headwater streams. This study investigated headwater stream macroinvertebrate communities in the H.J. Andrews Experimental Forest, Oregon, U.S.A and used a paired-stream study design to examine the effect of prior forest harvest on stream macroinvertebrates. Concomitantly, this study examined how macroinvertebrate life-history traits were related to stream size, substrates, discharge, or water temperature. Results from this study suggest that neither richness nor densities differed between streams flowing through young growth versus old growth forests. Despite similarities among these metrics, multivariate ordination techniques helped elucidate differences in benthic community composition between paired streams when red alder was present in riparian zones of previously harvested basins. Indicator Species Analysis of community composition and abundance revealed that no taxa were exclusively indicative of either forest type. Macroinvertebrate life-history traits among headwater streams were related to stream size, stream substrates, or stream discharge. As predicted, macroinvertebrates that ingest leaf litter (shredders) decreased proportionally with increasing stream width, while macroinvertebrates that scrape off algae and biofilms from instream substrates (scrapers) increased with increasing stream width. Differences in macroinvertebrate habit-trait groups were related to differences in stream substrates or stream discharge between very small headwater streams (