COS 206-1 - Land use and environmental determinants of spatial diversity patterns in California vernal pools

Abstract: Environmental factors occurring at local, regional, and biogeographic scales can affect spatial diversity patterns. Species with different traits can also respond differently to the environment and human activities to further explain diversity. While many freshwater ecosystems have been assessed in this context, seasonal aquatic ecosystems have been largely understudied. Vernal pools are seasonal wetlands that support high endemism and a greatly reduced habitat (< 10% still remain). Using vernal pool plant and animal data from across all of California, we assessed the contributions of climate, latitude, land use, and wetland characteristics on alpha, beta and gamma diversity.The data came from over 1000 California vernal pools from across over 10 degrees of latitude. Thirty animal taxa were categorized into dispersal and specialization traits. Over 400 plant species were identified and were categorized into four trait categories: all combinations of native or exotic and graminoid or forb. Generalized linear models and correlations were conducted to evaluate what variables were most associated with total diversity patterns as well as the functional groups. The best predictors of plant species diversity were amount of developed land cover, pool size, and latitude, while animal taxa were associated with pool size, latitude, and climate variables. Results indicated that developed land within a 1 km radius of vernal pools negatively influence plant species diversity within the pools. Functional groups differed in response to many of the independent variables. For example, native plant richness was negatively associated with increased developed land, but invasive plants were not associated with development. Latitude and pool size were positively associated with several species richness measures. Environmental variables and land use influence vernal pool plant and animal species and their functional groups, which is crucial for understanding these threatened and understudied habitats. They can also help managers better manage and restore vernal pools as habitat loss and climate change continue.