Landscape factors influence Odonata communities and species occupancy rates in California and Nevada

Freshwater habitats in the western United States have experienced highly altered water quality, stream flow and sediment regimes in recent decades. Despite the relative lack of knowledge on the conservation status of freshwater organisms in the region, studies have documented extinction rates of this group to be on par with tropical rainforests. Odonata may serve as good indicators of freshwater ecosystem conditions, in relation to broad-scale landscape factors such as climate, urbanization and tree cover. In this study, we use an occupancy modeling approach to determine how landscape and local habitat parameters influence both detection probability and occupancy rates of Odonata species in California and Nevada. We use a combination of single species and multi-species models to determine how landscape, local habitat, and site-visit parameters influence the occupancy rates and detection probabilities of habitat generalists and specialists with varying dispersal ability. We also explore how landscape factors influence community metrics, including species richness, jaccard similarity index, and traits (i.e. percent generalists, average tolerance value, dispersal ability). After adjusting for detection probability, we have found a significant increase in habitat generalists while habitat specialists decline in occupancy rates and homogenization of communities across sites.