| Forest canopies were recognized as hotspots of arthropod diversity in the early 1800s. Subsequent studies on forest canopies from Europe, South America, and Australia have continued to provide compelling evidence that global biodiversity may be much higher than previously thought. Unfortunately, the arboreal insects in temperate deciduous forests of North America have not been well studied. Thus, the purpose of this dissertation was to document baseline information on the ecology of tree-crown beetle communities in forests of Ohio and Indiana and address contemporary questions related to the regulation of local and regional diversity. These include the effects of spatial scale, phenology, and host-tree attributes.; Using insecticide fogging, I captured a total of 21,234 beetles (representing >700 species) between 1998 and 2000 from state parks, state forests, and nature preserves throughout southern Ohio and Indiana. Beetle communities were dominated by weevils (Curculionidae) and leaf beetles (Chrysomelidae) and showed pronounced seasonal changes. For example, beetle community composition exhibited a faunal overlap of <15% between June and August of 1998. Additive partitioning indicated that processes acting on the spatial scale of ecoregions produce a significant percentage of beetle species richness, whereas beetle species diversity is influenced more by processes at finer spatial scales. The relative contributions of alpha and beta diversity to regional diversity also changed over spatial scales, suggesting that different ecological processes dominate different spatial scales. At fine scales, these processes may be interspecific interactions, individualistic use of the tree crown environment, and responses to forest stand structure. Further indications of scale-specific diversity determinants emerged from my analysis on host tree attributes, which supported both ecological (e.g., geographic range of the host tree and plant size) and evolutionary hypotheses (e.g., taxonomic relatedness and pollination system) about insect-plant relationships.; Collectively, my dissertation indicates that arboreal beetle diversity in temperate deciduous forests is influenced by a suite of factors that operate over a range of spatial and temporal scales. Some of these factors—seasonal variation, scale dependence, and host-tree associations—are defining characteristics or arboreal beetle communities, such that ecologists can exploit them to better understand the regulation of species diversity in ecological communities. |
