INFLUENCE OF RIPARIAN VEGETATION AND SOILS ON STREAM MACROINVERTEBRATE COMMUNITIES IN COASTAL HEADWATERS OF BRITISH COLUMBIA: PROVIDING PERSPECTIVES FOR RIPARIAN MANAGEMENT.

J.D. Sleeman and J.S. Richardson. Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4

It is recognized that aquatic invertebrates are integral components of forested coastal ecosystems. However, we do not have the insight needed to properly manage coastal riparian areas with the maintenance of invertebrate communities as an objective. We hypothesize that retention of tree-patches, which balances the demands of ecology and economy- i.e., a patch of sufficient size that meets ecological management objectives, yet which remains financially rewarding; will have the potential to mitigate deleterious changes associated with harvesting. We have been investigating aggregate (group) retention management areas in headwater basins in British Columbia to test their effectiveness for mitigating the effects on the streams which run through them. This is a multi-year experiment comparing the effects of clear-cut harvesting and aggregate (group) retention along non-fish bearing reaches of coastal headwater stream channels. Studies are being conducted before and after implementation to monitor changes in riparian vegetation and aquatic invertebrate communities. We are performing reach-level leaf litter additions to streams within clear-cuts to investigate the relationships between organic matter inputs and invertebrate communities. We are also examining the influence of soils via groundwater transfer of dissolved organic carbon to understand the links that bind the stream communities to their adjacent riparian areas.