Epsilon Archive for Student Projects

Abstract

The goal of biological monitoring is to evaluate the effect of human activities on biological resources. In this study, I've looked closer into what happens with streams degraded by forestry. Seventeen streams in Stugun, Jamtland, were sampled for benthic fauna and water chemistry. Each watershed were analysed with maps, air photographs and by descriptions in field. The aim was to find changes in benthic fauna composition due to forest clear cutting. When there was no watershed that could be useful as a reference area, I had to construct an index of disturbance. To test my data I used several multivariate analyses (PCA, Twinspan, CA, CCA och RDA) and a multimetric index method. I found five attributes that could be possible indicators of disturbance (EPT taxa, filter feeders, Diptera, Baetis and
collectors/gatherers). No other set of data has been tested to confirm these indicators. No clear response in benthic fauna composition to catchment forestry was recorded, but the scores from the constructed multimetric index could distinguish disturbed stream sites from minimally disturbed stream sites (R2= 0,46). Principal component analysis (PCA) was also tested for the scores of benthic fauna and could distinguish different grades of influence, but not significantly.
Another study was performed in stream Slattflobacken. Four sample points were selected to compare different sections of the stream. One point was selected upstream a clear-cut area, one point in the clear-cut area and two points downstream the clear-cut area. The purpose was to see how the species composition varies in the same stream but with different grade of degradation by forestry. The variation was not big enough among the sample point to confirm that hypothesis.
Analysis of alkalinity, pH, conductivity and total phosphorus clearly showed a north-southern gradient, were watersheds south of river Indalsalven has low alkalinity, pH and conductivity, but high total phosphorus. These results could have effect on benthic species composition and could be one explanation why watersheds degraded by human activities does not clearly show changes in composition of benthic fauna.