Habitat Distribution of Carabid Beetles (Coleoptera: Carabidae) in Northern Hardwood Forests of Michigan

We compared carabid beetle communities in northern hardwood forests and divided these forests into three categories based on overstory composition and geographic location: Northern red oak-American beech (Quercus rubra L.-Fagus grandifolia Ehrh.) in the Lower Peninsula (OBLP), sugar maple- American beech (Acer saccharum Marsh.) in the Lower Peninsula (MBLP), and sugar maple- American beech in the Upper Peninsula (MBUP). Carabid beetles were collected using pitfall traps in 36 stands in 2003-2004. We found that carabid composition changed throughout the collection periods. Pterostichus pensylvanicus LeConte and Sphaeroderus lecontei Dejean comprised 76% of the trap catches in May while Synuchus impunctatus (Say) dominated 67% of the total August catches and the two May-dominant species made up less than 1% of the catch in August. Carabid activity-density was also significantly greater in MBLP forests compared to the other forest types in both years. Within the three northern hardwood forest types, five carabid species were significantly more abundant in one forest type: Carabus goryi Dejean (MBLP), Calathus gregarius Say (OBLP), Pterostichus adstrictus Eschscholtz, Pterostichus coracinus (Newman) and Psterostichus melanarius Illiger (MBUP). We found that stand-level differences within the same broadly-defined forest type (northern hardwood forests) support different carabid assemblages both temporally and spatially. Seasonal and habitat information about carabid beetles may be useful in determining optimal sampling periods for biodiversity sampling, using carabids as biological control agents against invasive pests, and evaluating potential impacts of non-native fauna on native carabids and other invertebrates. Carabid diversity and abundance data may help forest managers adopt sustainable management strategies that increase ecosystem biodiversity and resiliency at a time when invasives are threatening many ecosystems.