A comparison of the beetle (Coleoptera) fauna captured at two heights above the ground in a North American temperate deciduous forest
We compared the beetle fauna captured in 12 pairs of flight intercept traps suspended at two different heights above the ground ($15 m and 0.5 m) in a temperate deciduous forest in the southeastern United States to better understand how the abundance, species richness, diversity and composition of insect communities differ among forest strata. A total of 15,012 beetle specimens were collected representing 73 families and 558 morphospecies. Shannon’s diversity and evenness were both higher near the ground than in the canopy, but no differences in total abundance or species richness between the two layers were observed. There were many differences at the family level, however, and species composition differed considerably between the two layers. About 29% and 31% of species were captured exclusively in the canopy or near the ground, respectively. The canopy traps were more similar to one another than they were to those near the ground and vice-versa based on both Sorensen’s quotient of similarity and Raabe’s percentage of similarity. The canopy and ground trap locations were quite distinct based on nonmetric multidimensional scaling. The degree to which species composition was similar (i.e., Sorensen’s quotient of similarity) between pairs of traps decreased significantly with inter-trap distance for the traps in the canopy, but not for those near the ground, suggesting a more uniform community near the ground. Of the 41 families or subfamilies represented by more than 40 individuals, 12 were more abundant in the canopy and 14 were more abundant near the ground. Similarly, of the 16 families or subfamilies represented by more than 10 species, five were more species rich in the canopy and four were more species rich near the ground. Three families (Cerambycidae, Cleridae and Coccinellidae) were both more abundant and species rich in the canopy, whereas four other groups (Carabidae, Pselaphinae (Staphylinidae), Scolytinae (Curculionidae) and other Staphylinidae) were both more abundant and species rich near the ground. In addition to differing considerably among families, the vertical distribution patterns varied within many families as well. The distribution patterns for several groups are discussed in some detail with respect to known life history information.