SHORT-TERM EFFECTS OF 3 FORESTRY PRACTICES ON CARABID ASSEMBLAGES IN A JACK PINE FOREST

The effects of clear-cutting alone and clear-cutting followed by presc ribed burning or scarification on carabid beetle assemblages were inve stigated. Based on earlier studies, we hypothesized that each of these forestry practices would produce a different carabid assemblage on a short-term basis (1-2 years) and that carabid diversity, abundance, an d species richness would increase with the intensity of site preparati on. Carabids were sampled in a jack pine (Pinus banksiana Lamb.) fores t throughout the 1992 growing season using pitfall traps. A total of 5 970 adult carabids, belonging to 26 genera and 83 species, were collec ted Disturbed stands had similar or higher Shannon-Wiener diversities, number of catches, and number of carabid species when compared with u ndisturbed forest. Amara and Harpalus species were found almost exclus ively in disturbed sites. Clear-cutting followed by prescribed burning tended to have the greatest impact on carabid assemblages. Prescribed burning seemed particularly favourable for Syntomus americanus (Dejea n), Agonum placidum (Say), Amara erratica (Duftschmid), Amara convexa LeConte, Amara laevipennis Kirby, and Cicindela purpurea Olivier where as clear-cutting in general was associated with reduced catches of Cal athus gregarious (Say), Calathus ingratus Dejean, Calosoma frigidum Ki rby, Cymindis limbatus Dejean, Myas cyanescens Dejean, Pterostichus pe nsylvanicus LeConte, and Pterostichus tristis (Dejean). Our results su ggest that the presence of regenerating sites with and without prescri bed burning among the jack pine forest could contribute to the preserv ation of carabid diversity, although islands of mature forest may be n ecessary to avoid extermination of some old-growth carabid species.