Patterns of Arachnid Biodiversity in California

The California Biodiversity Hotspot is home to among the highest sympatric scorpion diversity in the world. For example, in California, as many as 11 species of scorpions may be found in the same place, and they occur in high densities with biomass estimates ranging up to 8.3 kg/ha. While many leaf litter arachnids can thrive in the patchiest of habitats, and in proximity to human development, they are sensitive to human-mediated change. We hypothesize that obligate burrowing arachnids (like trap door spiders and scorpions) are sensitive to soil compaction due to cattle grazing; and because many arachnids are dispersal-limited species, we hypothesize that leaf litter and burrowing arachnids (like scorpions, pseudoscorpions and wolf spiders) are susceptible to large-scale wildfires. This research will examine the impacts of two pressing conservation threats: land use change in California due to intensive grazing and mega-wildfire. In order to understand these effects we will 1) compare alpha diversity and abundance of adjacent natural areas that permit and prohibit cattle grazing; 2) compare alpha diversity and abundance in habitat burned by wildfire and not burned by wildfire, and by sampling a time-series of fires, the rate of dispersal back into burned areas over time.  Finally, we are continuing to document new-to-science species of arachnids endemic to the state. 

Funding: California Leaf Litter Arachnid Inventory and Archive, California Institute for Biodiversity. Population Genomics of the Western Forest Scorpion, California Conservation Genomics Project.