Assessing Climate Change Impacts on Vernal Pool Ecosystems and Endemic Branchiopods

This study evaluated the hydrologic sensitivity of vernal pool ecosystems in the Central Valley of California to climatic changes projected for 2100. A vernal pool water-balance model was used to evaluate rain-fed vernal pools at four locations under future conditions projected by two contrasting global climate models. The potential for change in the duration of continuous inundation, frequency of reproductively suitable inundation events, and the seasonal distribution of inundation was quantified. The potential impact of hydrologic changes varied by species and by location. Three scales of response were identified: (a) At the regional scale, pools in the middle of the Central Valley near Merced were the most responsive to climatic changes. (b) At the local scale, smaller, shallower pools had the greatest potential to change the distribution of reproductively suitable habitat available to branchiopods. (c) At the individual pool scale, changes in precipitation will dominate changes in temperature, resulting in relatively linear responses in the duration of inundation. The ecological impact of these changes will be determined by a balance between the increasing suitability of vernal pools for branchiopod predators and the hydrologic improvement of currently marginal habitats.