UCLA

Our objective was to gain an understanding of the influences of habitat context and seasonal and interannual factors on arthropod assemblage structure in a wetland environment. We hypothesized that river and pond riparian habitats in the wetland would have greater diversity and abundance than core wetland habitat, and that these differences would be driven by aquatic subsidy via emerging aquatic insects. We also hypothesized that diversity and abundance of terrestrial fauna would decline through the dry summer. We sampled the study wetland, in Yosemite National Park, California, USA, through the growing seasons of 2013 and 2014; a large wildfire (> 100,000 ha) burned the entire study site during late summer of 2013. Assemblage structure was strongly influenced by habitat context, season, and year. Diversity and abundance were high at the river riparian sites, but these results were driven by a diverse and abundant terrestrial fauna, rather than by large numbers of emerging aquatic insects. Faunal assemblages became increasingly depauperate through the summer, likely due to drying of wetland habitat in this hot Mediterranean-type climate. Fire probably had a strong influence on faunal assemblages and vegetation structure, but we cannot rule out interannual variability independent of the fire.