Effects of forest management practices on the diversity of ground-occurring beetles in mixed northern hardwood forests of the Great Lakes Region

Abstract

Ground-occurring Coleoptera were sampled over 2 years using pitfall traps in 23 northern hardwood or eastern hemlock-dominated sites representing even-aged, uneven-aged, or old growth forests. Overall, 65,586 individuals were obtained, representing 33 families and 192 species. Carabids comprised 54% of the total catch in 1996, when all the families were tallied. There was little variation in the number and relative abundance of carabid species caught between seasons. No differences in overall species richness or abundance were observed among forest management regimes or habitat types. However, there were substantial differences in species composition. Thirteen species showed significant habitat associations among the five forest management regimes, and 21 species were associated with specific habitat features of the sites, such as dominant tree species or canopy structure. More species (16) were affected by the presence of forest management than by tree species dominance (6) or canopy structure (5). Harpalus fulvilabris, Pterostichus coracinus, Carabus nemoralis, Glischrochilus siepmanni, Nicrophorus orbicollis, and Nicrophorus sayi were more commonly caught in managed than in old growth forest sites, while Carabus sylvosus, Platynus decentis and Oiceoptoma novaboracensis were more commonly associated with old growth sites. Calosoma frigidum and Necrophila americana were associated with northern hardwood sites, while Platynus decentis was significantly associated with sites dominated by eastern hemlock. Calosoma frigidum, Necrophila americana, and Nicrophorus vespilloides were more common in even-aged sites, while a lampyrid and a leiodid morphospecies were more common in sites with an uneven-aged canopy structure. The importance of microsite features was reflected in the high variability observed among sites and among traps within sites. Results indicate that conservation of a range of forest types is required in order to maintain the diversity of ground-occurring beetles on a regional scale. This will be quite challenging, since forest types such as old growth hemlock-hardwood are rare across the landscape due to habitat fragmentation and logging.