Long-term responses of ground beetles (Coleoptera: Carabidae) to clear-cutting and wildfire in lodgepole pine stands of western Alberta, Canada

We studied responses of carabid beetles (Coleoptera: Carabidae) to clear-cutting and wildfire in lodgepole pine forests in the foothills of Alberta, Canada during 2013-2014 and compared the results with those from a similar study conducted in the same area during 1989-1990. Assemblages from stands regenerating 12-53 years after harvest gradually recovered towards their presumed preharvest condition represented by old pyrogenic stands. Assemblage structure in postharvest stands of similar age had also largely converged with that in stands that had burned in 1957 and 1997. Composition of ground vegetation, mineral soil cover, and basal area of trees and shrubs were significantly correlated with carabid assemblage structure, suggesting that plant successional gradients and patterns in carabid assemblages are driven by similar factors. We found that no carabid species was strictly associated with old pyrogenic stands, although assemblages in pyrogenic stands were distinctive. We predict that composition of carabid assemblages in harvested stands will recover and roughly match the variable structure of assemblages remaining in old, never-cut pyrogenic stands, given sufficient time (≥ 50 years). Nonetheless, the carabid fauna of the eastern slopes of Alberta's Rocky Mountains appears to be changing in response to factors other than forestry. Warming climate is an explanation consistent with the changes observed.