RAPID: Using the historic Californian drought to gain a predictive understanding of the effects of severe climatic events on plant communities

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Drought in the California Floristic Province has recently reached record-setting severity, with 2013 having the lowest precipitation ever recorded in a calendar year. The proposed study will test predictions about which plant species and plant communities are most vulnerable to severe droughts and which ones are more resistant to drought. This will be done by gathering new data from the sites of five previous studies across California. Each of these previous studies examined how water availability affected plant communities, using either experimental water additions, comparisons of wetter and drier years, or comparisons of geographic locations with differing amounts of rainfall. Each of these studies provided evidence about which characteristics of plant species and communities make them more or less sensitive to water availability. Using the data collected in 2014, the same plant communities previously studied will be compared after versus before the drought, allowing this study to document which species and communities have changed the most in response to the drought. Next, this study will test whether the changes seen after versus before the drought are consistent with predictions based on the five earlier studies. As one example of the expected results, it is predicted that species with small, thick leaves will decline less in abundance than species with broader and thinner leaves, because these characteristics were previously found to predict the sensitivity of plant species to water availability. This research is urgent because effects of the drought can only be quantified by intensive resampling of the five datasets in spring-summer 2014.This study will confirm or reject generalizable predictions about the attributes of terrestrial plant species and communities that render them more or less vulnerable to drought. Severe droughts are expected to worsen with climate change, and so this research may have great potential applications to prediction of plant community composition with climate change. Additionally, the research will involve a female postdoctoral researcher. At the principal study location, the researchers will continue contributing to an outreach program that provides field science learning opportunities to 500 K-12 students per year in an under-served area.