Forest management strategy, spatial heterogeneity, and winter birds in Washington.

Abstract

Ecological management of second-growth forest holds great promise for conservation of biodiversity, yet little experimental evidence exists to compare alternative management approaches. Wintering birds are one of several groups of species most likely to be influenced by forest management activities. We compared species richness and proportion of stand area used over time by wintering birds in 16 second-growth Douglas-fir (Pseudotsuga menziesii) stands to determine the effects of management strategy and experimental variable-density thinnings. Management strategies were retaining legacies (large live, dead, and fallen trees from the previous old-growth stand) with long rotations and managing for high-quality timber with multiple thinnings and removal of defective trees. Experimental thinnings were designed to reduce inter-tree competition and monopolization of light, moisture, and nutrients by trees at the expense of other growth forms; reproduce the within-stand spatial heterogeneity found in oldgrowth forests; and accelerate development of habitat breadth. Proportion of area used and species richness increased with experimental thinnings. Two of the 8 most common winter species increased their use of experimentally thinned stands. No species exhibited greater use of unthinned, competitive-exclusion-stage stands over thinned stands. Variable-density thinnings, in conjunction with other conservation measures (legacy retention, decadence management, and long rotations), should provide habitat for abundant and diverse birds.

Citation

Haveri, B.; Carey, A.B. 2000. Forest management strategy, spatial heterogeneity, and winter birds in Washington. Wildlife Society Bulletin. 28(3): 643-652