Tuesday, May 27, 2008
279

The relative roles of landscape, riparian and instream factors to macroinvertebrate composition in local catchments: Changed country borders as landscape experiments

Johan Törnblom1, Per Angelstam1, Erik Degerman2, Lennart Henrikson3, Tobias Edman4, and Johan Temnerud5. (1) Swedish University of Agricultural Sciences, Faculty of Forest Sciences, School for Forest Engineers (SLU), SE-739 21, Skinnskatteberg, Sweden, (2) The Freshwater Laboratory, National Board of Fisheries,, SE-702 15, Örebro, Sweden, (3) Freshwater Programme, WWF, Ulriksdals Slott, SE-170 81, Solna, Sweden, (4) Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, Faculty of Forest Sciences, SE-230 53, Alnarp, Sweden, (5) Department of Environmental Assessment, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden


Abstract
Landscape composition, riparian vegetation, instream habitat characteristics and stream macroinvertebrate assemblages were studied in 25 catchments in the Carpathian Mountains of Central Europe. This ecoregion was selected because of its interesting history of forest and agricultural ecosystems among neighbouring countries. Canonical Correspondence Analysis showed that among-stream variation in invertebrate assemblages was primarily related to four landscape variables. Principal Component Analysis (PCA) indicated that land use/cover and stream channel substrates co-varied. PCA also showed that chemical variables, including organic carbon, had higher values in the agricultural landscape than in natural forests. The major source of variation among taxa in the streams was a higher abundance of Diptera in agricultural landscapes and of Plecoptera, Coleoptera, Trichoptera and Amphipoda in forests. Gastropoda and Oligochaeta were more abundant in open, fine-grained agricultural landscapes with scattered trees. Ephemeroptera species were quite indifferent to these gradients in catchment land cover, but showed a tendency of being more abundant in the pre-industrial cultural landscape. Our findings suggest that land use management at the catchment scale is needed for efficient conservation and restoration of stream invertebrate communities. Carefully designed habitat-species dose-response studies covering the gradient from reference landscapes to severely altered landscapes are an important next step.



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