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Monday, April 9 • 3:30pm - 3:45pm
INSECT ECOLOGY: Spatial Variation in Diversity and Composition of Canopy Spiders in Eastern Deciduous Forests

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AUTHORS: Hannah J. Penn, Michael B. Mahon*, Thomas O. Crist – Miami University

ABSTRACT: Over the last two decades, ecologists have focused on how patterns of species diversity vary across spatial scales. However, the relative contribution of local, landscape, and regional factors influencing species diversity are unknown for most taxa, particularly invertebrates. We studied how the diversity and composition of forest-canopy spiders (Araneae) vary across nested spatial scales, ranging from individual trees to ecoregions. To address this question, we used a hierarchically scaled design to sample spiders in tree crowns in forests in southern Ohio and Indiana, USA. Four hierarchical levels comprised the nested design: individual tree, forest stand, site, and ecoregion. Spiders were knocked down with insecticidal fogging and collected using 12 funnels below trees. A total of 96 trees were sampled in June and August 2000. We used hierarchical diversity partitioning to understand the distribution of spider diversity across spatial scales. We used randomization procedures to test the significance of alpha and beta diversity against null distributions at each spatial scale. These randomization procedures were based on the PARTITION software developed by Crist et al. 2003 using a newly developed R package: PARTITION. Additionally, we used PERMANOVA and NMDS ordination to examine community composition at each spatial scale. Within tree (alpha) accounted for 9% of gamma (total regional) diversity, while between trees, forest stand, site, and ecoregion accounted for 21%, 15%, 32%, and 23%, respectively, of gamma diversity. Diversity is driven by both local (individual tree) and larger spatial scales (site and ecoregion), as revealed by partitioning of diversity. Conversely, ordination indicated stand-level characteristics appear to be the most important source of variation in species composition across scales. Our results indicate that both local and regional factors are important in determining the species diversity and composition of forest-canopy spiders across spatial scales.

Monday April 9, 2018 3:30pm - 3:45pm CDT
LaSalle 2 (7th Floor)

Attendees (6)