Vegetative communities as indicators of ground beetle (Coleoptera: Carabidae) diversity

Formally assessing biodiversity can be a daunting if not impossible task.  Subsequently, specific taxa are often chosen as indicators of patterns of diversity as a whole.  Mapping the locations of indicator taxa can inform conservation planning by identifying land units for management strategies.  For this approach to be successful, though, land units must be effective spatial representations of the species assemblages present on the landscape.   In this study, I determined whether land units classified by vegetative communities predicted the community structure of a diverse group of invertebrates—the ground beetles (Coleoptera: Carabidae).  Specifically, that (1) land units of the same classification contained similar carabid species assemblages and that (2) differences in species structure were correlated with variation in land unit characteristics, including canopy and ground cover, vegetation structure, tree density, leaf litter depth, and soil moisture.  The study site, the Braidwood Dunes and Savanna Nature Preserve in Will County, Illinois is a mosaic of differing land units.  Beetles were sampled continuously via pitfall trapping across an entire active season from 2011–2012.  Land unit characteristics were measured in July 2012.  Nonmetric multidimensional scaling (NMDS) ordinated the land units by their carabid assemblages into five ecologically meaningful clusters: disturbed, marsh, prairie, restoration, and savanna.  The subset of land unit characteristics with the highest rank correlation with the NMDS ordination included soil moisture, leaf litter depth, percentage of canopy cover, and percentage of grass ground cover.  Land units classified by vegetative communities effectively represented carabid species assemblages.