Landscape and area effects on beetle assemblages in Ontario

Abstract

We compared beetles collected from eight forest fragments in a suburban‐agricultural setting and one contiguous forest in south‐central Ontario. Samples were collected by pan traps from the interior of continuous forest and upland deciduous forest fragments ranging in size from 43 to 2350 ha. The pooled sample was composed of 4561 individuals from 117 species. Differences in beetle assemblages was primarily due to variation in patch isolation, although actual fragment size had a significant effect on the abundance of native and forest specializing carabid species, and the amount of forest interior habitat had a significant effect on the total number of beetle species and ground beetle species richness (family Carabidae). Fragments which were less isolated on a local scale (within a 2 km radius) had a species composition most similar to that found in continuous forest, regardless of whether the actual forest area was small or large. Marked differences in abundance and biomass were also attributed to variation in the amount of local forest cover. We suggest that a reduction in patch isolation may be an appropriate conservation strategy to improve beetle diversity and abundance in fragmented landscapes.