The effects of patch harvesting and site preparation on ground beetles (Coleoptera, Carabidae) in yellow birch dominated forests of southeastern Quebec

We studied the impacts of increasing size and number of gapcuts and the effects of site preparation by scarification on the species richness and community composition of ground beetles (Coleoptera: Carabidae), using pitfall traps in early-successional yellow birch dominated forests in eastern Canada. Catches of all carabids, forest specialists, and generalists were generally higher in uncut controls than in treatments. The catch of open-habitat specialists was generally lower in controls than in treatments. Although not significant, there was a common trend for scarification to decrease the catches of forest specialists and generalists. Bray-Curtis similarity measures and nonmetric multidimensional scaling ordination indicated that the composition of the carabid assemblage was more affected by harvesting treatment than by scarification. Carabid species composition varied consistently with increasing gap size and corresponded to the a priori generalized habitat-preference designations. Forest-specialist species were confined to uncut sites, while generalist species were widely distributed across all sites. Open-habitat species were found predominantly in clear-cut and two-gap sites. Hygrophilous species were consistently associated with two-gap, four-gap, and clear-cut sites. Small-gap harvesting is more favorable to the maintenance of the structure of natural arthropod assemblages than are traditional, larger clearcuts.