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Presented at the NABS Annual meeting, Athens, Georgia, 2003
in Food Webs
Invertebrate productivity of small streams in western Washington
C.J. Volk1, P.M. Kiffney2, and R.L. Edmonds1. 1College of Forest Resources, University of Washington, Seattle, Washington, USA 98195, 2National Marine Fisheries Service, Northwest Fisheries Science Center, Mukilteo Biological Field Station, Mukilteo, Washington, USA 98275
Substantial declines in Pacific Northwest (PNW) salmon runs have led to a 90% reduction in stream nutrients. There is a need to understand how changes in the inputs of these limiting resources have affected PNW watersheds and to develop restoration strategies for these lost subsidies. Nitrogen–fixing red alder (Alnus rubra) may provide critical nutrient resources for fish and amphibians. In the PNW, natural disturbance events (e.g. fire) and clearcutting have created a predominance of red alder in riparian corridors, although alder removal and conifer replanting is still a common riparian forest restoration practice. Nutrient subsides from alder forests to streams can potentially increase biomass and production at all trophic levels via bottom–up control and alleviate nutrient limitation. In the summer of 2001, drifting and emerging invertebrates were collected from six different streams in western Washington, three dominated by red alder and three by old–growth coniferous forest. We have initially found higher abundances of emergent invertebrates in streams dominated by red alder than old–growth forest. Alder–forested headwater streams may provide critical food resources to both terrestrial and aquatic species in localized and downstream habitats.
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