With climate change a certainty, and many emerging cases of biotic shifts in response, there is an urgent need to understand the relative risks faced by different groups of species. Forecasts of the biotic effects of climate change usually begin by assuming that species niches are tightly controlled by climate. An obvious limitation is that this approach does not deal with other factors controlling species niches, including soils and species interactions. Edaphic endemics (species that exist on certain soil types) present a very important special case in which the climatic niche approach is less likely to work. To understand the degree of risk faced by these special floras, it is important to understand how climate change affects the relative performance of endemics and the non-endemics with which they compete, across a range of available soils.

With collaborators Susan Harrison and Mark Schwartz at UC-Davis, and Jim Grace at the USGS, we are testing whether specialized serpentine endemic plants are at heightened risk from global climate change, and whether the presence of competitors alters their fate under scenarios of increased or reduced precipitation. We are using a rare historical dataset from eminent ecologist, Robert Whittaker, and current plant community data to test our hypotheses. This work will both shed new light on the observed biogeographic gradients in the richness and composition of this flora, and will allow us to assess the sensitivity of this flora to future human-induced drying or wetting of the climate.

In addition to understanding climate change effects on edaphic endemics, we are also determining ecological controls over edaphic endemic plant diversity. This research will take place in serpentine outcrops of California and in the special substrates (sandstone, limestone, dolomite) of the Ozark glades in Missouri.