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Use of habitat features, edges and harvest treatments by spruce grouse in subalpine forest

Huggard, David J.
Forest ecology and management 2003 v.175 no.1-3 pp. 531–544
canopy, cutting, edge effects, forests, grouse, habitats, models, shrubs, silvicultural systems, snowmelt, topography, trees, wetlands, British Columbia
Winter use of habitat features, edges and alternative forest harvest types by spruce grouse (Falcipennis canadensis) was measured at the Sicamous Creek Silvicultural Systems site in high-elevation forest in south-central British Columbia, Canada. Habitat relationships and edge effects were tested at five other validation sites. Winter use by grouse was indicated by droppings in habitat plots or edge transects conducted shortly after snowmelt. Assumptions of using droppings to indicate grouse occurrence were assessed. Grouse high-use areas (100 m-radius) were distinguished from areas available overall by higher densities but lower basal areas of fir and spruce trees, presence of surficial rock and sparse shrub cover. Plots of 0.01 ha used by grouse within high-use areas were distinguished from unused plots by these same habitat features, plus greater canopy cover and more relatively short trees. Knolls were preferred topography types, as predicted by this habitat model. Use of forest was reduced within 10 m of recently harvested openings of 0.1, 1 and 10 ha, and within 20 m of older large openings. Use increased with proximity to open wetlands until 20 m from the wetland, paralleling predicted habitat quality, then declined nearer to the edge despite high predicted quality. Percent decline in winter occurrence of grouse was similar to the percent timber removed (33%) in harvest treatments with 0.1, 1 and 10 ha openings, but a more pronounced decline occurred in uniform partial cuts, where uniform thinning lowered predicted habitat quality. Recommendations to maintain winter habitat for spruce grouse in managed high-elevation forests include maintaining forest patches on knolls or other poor growing sites and around wetlands, ensuring some retained area >10 m from harvested and natural edges, and avoiding widespread use of uniform partial cutting.