Meeting Abstract
105.4 Tuesday, Jan. 7 08:45 Responses of a grassland spider community to disturbance from fire and bison grazing GOMEZ, J.E.*; JOERN, A.; Kansas State University; Kansas State University jegomez@k-state.edu
A major overarching hypothesis in community ecology is that habitat spatial and temporal heterogeneity promotes species diversity. In grassland ecosystems, such spatial and temporal heterogeneity at the landscape level results from the interaction of fire, ungulate grazing and climate ecosystem drivers. Ubiquitous arthropod predators like spiders on grassland systems modulate prey community and ecosystem processes. Responses of predators (spider communities) to major disturbances on grassland ecosystems have not been study in detail. At Konza Prairie Biological Station, unique long-term manipulations (fire frequency and bison grazing) at watershed levels have resulted in a mosaic of habitat types. The habitat complexity and heterogeneity hypothesis: predicts that the overall abundance and species diversity increases with spatial heterogeneity of habitat structure. To address this hypothesis 23 sites were established along a gradient of habitat in bison grazed and ungrazed watersheds at KPBS. At each sites the spider and insect communities were sampled using vacuum and sweep-nets. And a series of vegetation characteristics were measured to characterize the spatial heterogeneity and structural complexity of each site. Preliminary results for this study indicate that species richness increases within the growing season. Spider abundance increases on ungrazed sites may result from an increase in spatial heterogeneity and microhabitat diversity with plant growth over the summer. Spider diversity and abundance increased over time (during the summer) independently from fire frequency. This may be promoted by higher microhabitat availability latter in the growing season as result of plant growth differentiation. Bison grazing influenced habitat heterogeneity maximizing microhabitat availability and use early in the summer.
