Effect of Oak Barren Restoration on Carabidae (Coleoptera) within a Kame-Kettle Bog System

Abstract

Carabid diversity may provide remarkable indicators of habitat type. We tested how habitat affinities of ground beetles correspond to restoration success for black oak barrens previously assessed for understory flora. Three different restoration techniques were applied to set back succession of encroaching woodlands and to open the habitat: selective canopy tree removal favoring 5% to 30% tree canopy cover, removal of thick forest floor leaf litter, or prescribed fire. All methods were set within 35 × 35 m plots spread across 10 glacial kames, which are mounds of sand and gravel deposited by melting ice sheets. Baseline surveys using pitfall traps obtained 21 species of Carabidae, almost all of which were characterized as woodland species. Imposing disturbance increased species numbers to 28, with 11 newly discovered and four not found in the resurvey. Of the new inhabitants, four species known to use grasslands and one woodland edge species had become common, while numerous woodland species declined in abundance. This marked community change in Carabidae occurred primarily after select canopy tree removal, which was the treatment that best shifted the forest back to a mosaic of open oak sand barrens and grassland. Prescribed burns only increased one woodland edge species that also appeared after canopy thinning and leaf litter removal. Change in the carabid species indicated success in shifting habitat and, concurrently, shifting understory plants increased diversity of carabids towards species that may be lost should the region remain dominated by homogenous closed-canopy forest.