Habitat restoration opportunities, climatic niche contraction, and conservation biogeography in California's San Joaquin Desert.

A recent global trend toward retirement of farmland presents opportunities to reclaim habitat for threatened and endangered species. We examine habitat restoration opportunities in one of the world's most converted landscapes, California's San Joaquin Desert (SJD). Despite the presence of 35 threatened and endangered species, agricultural expansion continues to drive habitat loss in the SJD, even as marginal farmland is retired. Over the next decades a combination of factors, including salinization, climate change, and historical groundwater overdraft, are projected to lead to the retirement of more than 2,000 km2 of farmland in the SJD. To promote strategic habitat protection and restoration, we conducted a quantitative assessment of habitat loss and fragmentation, habitat suitability, climatic niche stability, climate change impacts, habitat protection, and reintroduction opportunities for an umbrella species of the SJD, the endangered blunt-nosed leopard lizard (Gambelia sila). We use our suitability models, in conjunction with modern and historical land use maps, to estimate the historical and modern rate of habitat loss to development. The estimated amount of habitat lost since the species became protected under endangered species law in 1967 is greater than the total amount of habitat currently protected through public ownership and conservation easement. We document climatic niche contraction and associated range contraction away from the more mesic margins of the species' historical distribution, driven by the anthropogenic introduction of exotic grasses and forbs. The impact of exotic species on G. sila range dynamics appears to be still unfolding. Finally, we use NASA fallowed area maps to identify 610 km2 of fallowed or retired agricultural land with high potential to again serve as habitat. We discuss conservation strategies in light of the potential for habitat restoration and multiple drivers of ongoing and historical habitat loss.

Contemporary Drought and Future Effects of Climate Change on the Endangered Blunt-Nosed Leopard Lizard, Gambelia sila.

Extreme weather events can provide unique opportunities for testing models that predict the effect of climate change. Droughts of increasing severity have been predicted under numerous models, thus contemporary droughts may allow us to test these models prior to the onset of the more extreme effects predicted with a changing climate. In the third year of an ongoing severe drought, surveys failed to detect neonate endangered blunt-nosed leopard lizards in a subset of previously surveyed populations where we expected to see them. By conducting surveys at a large number of sites across the range of the species over a short time span, we were able to establish a strong positive correlation between winter precipitation and the presence of neonate leopard lizards over geographic space. Our results are consistent with those of numerous longitudinal studies and are in accordance with predictive climate change models. We suggest that scientists can take immediate advantage of droughts while they are still in progress to test patterns of occurrence in other drought-sensitive species and thus provide for more robust models of climate change effects on biodiversity.