Ground beetle responses to patch retention harvesting in high elevation forests of British Columbia

The effect of a forest harvesting system whereby small (typically 0.1-2.0 ha) patches of standing timber are retained inside of harvests, was compared to conventional clearcutting for its effect on ground beetle assemblages. Two seasons of pitfall trapping entailed 46451 trap days, and yielded 15799 individuals of 28 species; abundance was dominated by four species comprising 92.4% of the catch. Most species were known to have wide geographic distributions in Canada and Alaska but many species seemed to respond to disturbance on a site-specific basis. Contrary to findings of similar studies, no species could be characterized as "mature-forest specialists", or "forest generalists". Forest patches and edge habitats immediately inside the forest canopy contained assemblages more closely related to mature forest than to cleared areas. Harvested areas with patches yielded catches distinct from typical clearcuts, based primarily on changes in abundance of one common species. Climatic regimes and landscape disturbance levels were the two important factors distinguishing our study from others, and we have suggested that these may influence the degree to which patches are an effective conservation tool.