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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Land/Water Interfaces
BENTHIC INVERTEBRATE COMMUNITIES COLONIZING RED ALDER AND CONIFER WOOD IN HEADWATER STREAMS, PRINCE OF WALES ISLAND, SOUTHEAST ALASKA.
R.K. Kimbirauskas1, R.W. Merritt1, M.S. Wipfli2, and P.E. Hennon3. 1Department of Entomology, Michigan State University, East Lansing, MI 48823, 2Pacific Northwest Research Station, USDA Forest Service, 1133 N. Western Avenue, Wenatchee, WA 98801, 3State and Private Forestry, USDA Forest Service, 2770 Sherwood Lane, Juneau, AK 99801
Timber harvesting within and along riparian zones creates a disturbance that affects both physical and biological characteristics of adjacent streams and rivers. Red alder (Alnus rubra Bong.), a common hardwood in the Pacific Northwest, is an aggressive pioneer species following soil disturbance and often colonizes along streams, particularly following timber harvesting. We hypothesized that aquatic invertebrate abundance and species richness would be greater in streams within alder-conifer mixed young-growth riparian stands than in conifer young-growth stands, and would be greater on stream alder woody debris than conifer woody debris. This hypothesis was tested in 13
headwater streams within the Maybeso Creek drainage on Prince Of Wales Island, Southeast Alaska. Sampling sites were selected within riparian vegetation plots that represented a range of alder-conifer mixtures (0-53%). We used two approaches: (1) collections of naturally occurring woody debris, and (2) experimentally adding woody debris to streams. Invertebrate community composition on alder and spruce were compared across two distinct decay classes (early and late decay). The dominant invertebrates were Diptera (Chironomidae), Ephemeroptera (Baetidae, Heptageniidae) and Plecoptera (Nemouridae). Preliminary analysis of data shows that both aquatic invertebrate abundance and species richness increased in streams when alder was present in their associated riparian forests.
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