Ground dwelling beetles in early and late successional forests in the western Cascades of Oregon

The effects of forest cutting on forested systems and the biotic components of those systems has been at the forefront of scientific research. The inventory and monitoring of biodiversity is one technique used for measuring the effects of forest management. Because bioinventory studies are expensive, indicator species are often sought to serve as surrogates for the entire biotic community. Insects may be useful as indicator species. The purpose of this study was to perform an inventory of the ground dwelling beetles of the H.J. Andrews Experimental Forest, and then use that inventory to assess the impact of forest management. Beetle communities were compared over time (17 years) and across variously aged stands and associated floral communities to determine the effects of clear-cut management. Pitfall traps were used at 37 sites to collect ground dwelling Coleoptera over a three week period in 1982, 1983, and 1999. A total of 11,191 individuals of 224 species were collected.
The resultant catch was analyzed using univariate and multivariate statistical techniques. Results showed significantly different beetle communities among the four seral stages sampled. Beetles were more abundant in old growth sites. Species diversity was highest in clear-cut sites. Vegetation association was shown to significantly affect beetle communities, but was dependent on level of definition. Time also significantly affected beetle communities, with the beetle assemblages following a predictable trajectory parallel to vegetation succession. Functional group composition was found to change significantly over time, but was inconsistent between years.