| Summary: | Thesis (M.Sc.)--Memorial University of Newfoundland, 2003. Biology Includes bibliographical references The effectiveness of managed buffer zones in protecting an aquatic ecosystem during forest harvesting was studied for a two year period on a small headwater stream in northeastern Newfoundland, Canada. The study consisted of examining several components including abiotic (water temperature and sedimentation) and biotic (macroinvertebrates and salmonids). These components were studied pre- and post-harvest to determine the impact of the following riparian management schemes: 20 m no harvest buffer; 20 m buffer with 30 % of the basal area harvested; 30-50 m buffer with 30 % of the basal area harvested; and a no harvest 'control' site. -- Sedimentation significantly increased for the 20 m buffer with selective harvesting. Water temperature was slightly impacted within the optimum temperature class for brook trout (Salvelinus foniinalis) only with a significant decrease for the 30-50 m buffer with selective harvesting and the 20 m buffer with selective harvesting. The stress and lethal temperature classes were not significantly different between pre- and post-harvest observations. The water temperature significantly increased within the upper and lethal temperature classes for Atlantic salmon (Salmo salar) within the 30-50 m buffer with selective harvesting. -- The effects of selective harvesting on aquatic macroinvertebrates varied depending on the index and taxon. The number of Ephemeroptera, Plecoptera, and Trichoptera (EPT) divided by the number of Diptera index was not significantly affected by site and year. However, the number of total EPT? Ephemeroptera, Plecoptera, Trichoptera, Diptera (excluding Chironomidae) and Chironomidae were all significantly affected by site and year. The most notable difference between pre- and post-harvest occurred within the 20 m buffer, where a large increase in Oxythira sp., an algal consumer, was observed. The number of species observed for each of the sites was slightly greater post-harvest, however the differences were not significant. -- Brook trout and Atlantic salmon populations significantly increased for all three experimental sites except for brook trout within the 20 m buffer site. The biomass of brook trout significantly increased within the 20 m buffer with selective harvesting, while all other differences for brook trout and Atlantic salmon biomass were not significant. Young-of-the-year salmonid populations increased for all three experimental sites, with the exception of brook trout within the 20 m buffer. Young-of-the-year saimonid biomass was not significantly different for any of the experimental sites. For year 1 + and older Atlantic salmon populations, the 20 m buffer displayed the only significant increase between pre- and post-harvest The brook trout population estimates were not significantly different for any of the experimental sites as compared to the no harvest site. The biomass of both salmonid species were not significantly different for any of the experimental sites. -- Overall, the reach with the 30-50 m buffer with selective harvesting appeared to be the least impacted, specifically in terms of sedimentation and invertebrate community changes. These results suggest that managed buffers in this area of Newfoundland should be 30-50 m. -- The results of this study should be cautiously interpreted, owing to the short post- harvest assessment, and longer term monitoring is recommended to assess the implications of harvesting with managed buffers.
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