Loss of Diversity as a Consequence of Habitat Destruction in California Vernal Pools

Habitat destruction often results in the loss of biodiversity in natural communities. Vernal pools are a feature of California’s native landscape which have been heavily impacted over the past century by agricultural and urban development. Current estimates of vernal pool losses in the Central Valley range from 50-85% of pre-settlement acreages. In this paper I apply data from recent field surveys of vernal pool crustacean assemblages to a model developed by Koopowitz et al. (1994) in order to investigate the potential magnitude of species extinctions and loss of biodiversity resulting from the conversion of vernal pool habitats by human activities in the Central Valley. Based on observed species distribution profiles and habitat loss estimates of 50-85%, the model predicts that 15% to 33% of the original biodiversity of Central Valley vernal pool crustaceans has been lost since the 1800’s. The high rate of extinction expected to result from loss of vernal pools is due to the large proportion of species which are sporadic in distribution and relatively rare in occurrence. These results suggest that, although a handful of vernal pool crustaceans are currently federally listed as Threatened or Endangered, it is likely that many other less conspicuous species are also in danger of extinction. It is critical that the nature of species distribution patterns be used to develop policies aimed at adequate levels of vernal pool habitat preservation, and that mitigation efforts such as the creation of artificial pools ensure the maintenance of species which are rare endemics. CITATION. Pages 119-123 in: C.W. Witham, E.T. Bauder, D. Belk, W.R. Ferren Jr., and R. Ornduff (Editors). Ecology, Conservation, and Management of Vernal Pool Ecosystems – Proceedings from a 1996 Conference. California Native Plant Society, Sacramento, CA. 1998.