Nitrogen budget of a subarctic stream altered by beaver (Castor canadensis) |
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Authors: | Robert J Naiman Jerry M Melillo |
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Institution: | (1) Woods Hole Oceanographic Institution, 02543 Woods Hole, MA, USA;(2) Marine Biological Laboratory, The Ecosystem Center, 02543 Woods Hole, MA, USA |
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Abstract: | Beaver (Castor canadensis) influence stream ecosystems through their wood cutting and dam building activities. To quantify this influence we have used measured rates of nitrogen dynamics to construct a nitrogen budget for a section of a second order stream in eastern Québec and a beaver dam in that stream. The budget demonstrates the importance of sediment accumulations and an expanded wetted area to the annual nitrogen economy and to pathways of nitrogen cycling. Major changes after impoundment (per unit area) include a reduction in allochthonous nitrogen and an increase in nitrogen fixation by sediment microbes. Overall, the beaver-modified section accumulated 103 times more nitrogen than before alteration. The ecosystem implications of beaver activity suggest that current concepts of patterns and processes in running waters require modification.Research support by NSF grant DEB 81-05677 and the Woods Hole Oceanographic Institution. this is Contribution No. 5565 from the Woods Hole Oceanographic Institution and No. 88 from the Institution's Matamek Research Station |
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