Patterns of Beetle (Coleoptera) Diversity in Crowns of Representative Tree Species in an Old-Growth Temperate Deciduous Forest

Abstract

Patterns of spatial variation, temporal change, and host-tree differences of beetle communities in crowns of representative tree species were examined in an old-growth temperate deciduous forest in Hueston Woods State Park, Preble County, southwestern Ohio in 1998. The three study plots were separated spatially. Each had two 1-ha subplots containing one individual of four tree species: American beech (Fagus grandifolia), sugar maple (Acer saccharum), red oak (Quercus rubra), and white oak (Quercus alba). We obtained samples of the insect communities from one subplot per day using insecticide fogging, for a total of six sampling days in early summer (18 June-6 July 1998) and late summer (21 August-5 September 1998). A total of 1459 beetles representing 272 morphospecies and > 40 families were captured. Two-way mixed ANOVA models identified significant interaction effects (plot × tree species) on mean beetle richness and abundance in the early summer, but only tree species effects were identified in late summer. Although spatial variation may be a key diversity determinant in the early season, attributes of tree species, such as constitutive defenses, may be more important in late summer. Species richness, which exhibited a marked decline from early summer (194 morphospecies) to late summer (119 morphospecies), was coupled with only a 10% similarity between beetle assemblages during these periods. Abundance and composition changes between samples suggest that species-specific patterns of emergence and voltinism may be instrumental in structuring arboreal beetle communities in temperate tree crowns. This study highlights the need for detailed studies on recolonization and spatial dependence of arboreal insect communities in temperate forest ecosystems.