Differential patterns of taxonomic and functional diversity for two groups of canopy arthropods across spatial scales

Aim Arthropod diversity is often linked to variation in resource use, dispersal ability, habitat connectivity, and climate factors that differ across spatial scales. The aim of this research was to examine how species richness, functional diversity, and community composition of two taxa differing in functional roles and dispersal ability are structured across spatial scales and to identify the importance of vegetation, climate, and landscape in explaining these patterns at different scales. Location 96 trees in 24 stands of 6 deciduous forest sites in 2 ecoregions of the eastern USA (North-Central Till Plain and Western Allegheny Plateau) Time period 2000 Major taxa studied Canopy dwelling ants (Hymenoptera: Formicidae) and spiders (Araneae) Methods Organisms were collected from tree canopies using insecticidal fogging. Ant and spider taxonomic and functional beta diversity were partitioned across four hierarchical spatial scales (individual tree, forest stand, site, and ecoregion). The contribution of climactic, landscape, and vegetation variables was determined using model selection. Results Ant and spider species richness, functional diversity, and community composition differed between taxa and across spatial scales. Alpha diversity (within trees) was lower than expected for both taxa and types of diversity, with host tree species supporting different species of ants and spiders. While beta components of species diversity among trees and forest stands was greater than expected for both taxa, spiders also showed significant levels of beta diversity among sites. Functional beta diversity was less scale-dependent than taxonomic beta diversity. Stand-level patterns of beta diversity were significantly predicted by variation in climate and landscape connectivity. Main conclusions Effects of climate and landscape fragmentation on the diversity and community structure of both taxa indicate that anthropogenic climate change and land use change will alter canopy arthropod communities. Results also suggest that patterns of diversity among fragmentation metrics is influenced by differences in dispersal ability.