Community structure and spatial ecology of natural and restored California vernal pools

Species diversity and composition patterns in communities are the result of a multitude of factors acting at different spatial and temporal scales. Ecologists have utilized a variety of statistical approaches to examine these patterns of biodiversity with interest in inferring underlying mechanisms. The purpose of this study was to understand the local (vernal pool) and regional (site) scale community patterns in natural and restored California vernal pools, a threatened ecosystem. Previously published data on vernal pool aquatic invertebrates were reanalyzed using four approaches to identify factors influencing spatial diversity patterns: Species-Area relationships, Local-Regional relationship, Multiple Regression, and Community Assembly. Natural communities exhibited saturating curves for species-area relationships, implying a maximum number of species that an individual pool can support. Local-regional relationships were consistently linear, an indication of regional regulation of local diversity. However, when pool size was taken into consideration, the relationship became saturated. Total vernal pool species were strongly influenced by various abiotic measurements, and individual taxonomic groups responded differently to these measurements. Community assembly results indicated that species co-occurred more often than expected by chance, but different patterns were exhibited at different spatial scales and by individual taxonomic groups. Natural and restored vernal pools also differed in several significant measures and characteristics. Vernal pool communities varied as a function of local and regional habitat variables. These results indicated that an understanding of the spatial structure of natural and restored vernal pool communities can provide a useful framework for effective management and restoration of this unique and threatened ecosystem.