Intellectual merit: Globally, the diversity of plants and animals is highest in regions where rainfall and solar energy are abundant, which yields high rates of carbon capture via photosynthesis termed primary productivity. This project will analyze a previously unexamined aspect of this pattern, namely, how productivity affects the degree to which plants are specialized on different soils, which can drive the variation in species composition among different locations. In productive climates, this project will test the hypothesis that plant communities on different soils will be highly distinct because intensified competition leads to narrower soil niches, whereas in colder or more arid climates less distinctiveness of plant communities across soil boundaries is predicted. These predictions will be tested by comparing plant communities on chemically unusual soils such as serpentine, limestone, and dolomite, to those on nearby normal soils, across gradients of high to low rainfall in California and the Ozarks. To better understand the mechanisms for the observed patterns, experimental manipulations of rainfall and plant competition in neighboring serpentine and non-serpentine plant communities in California will be conducted. This research is important because plant species and communities endemic to particular soils are important contributors to global botanical diversity. Our results will help understand how climate controls plant diversity, plant community composition, and the degree to which plant communities are affected by biological invasions.
Broader impacts: A graduate student from an underrepresented group and several undergraduates will be trained with this award. Data will be made available to researchers, agency scientists, and nonprofit environmental groups through the data archives of the Knowledge Network for Biocomplexity (knb.ecoinformatics.org) and the UC Natural Reserve System Data Registry.
Globally, climate-drtiven productivity (abundant rainfall and solar energy) is the strongest predictor of plant and animal diversity. A little understood aspect of this pattern is that productivity is associated with high beta diversity, or differentiation of species composition among adjacent communities. We found that for Californian plants, higher productivity (rainier climates) led to higher beta diversity by causing greater specialization of plant species to either fertile nonserpentine or infertile serpentine soils. Ciommunities on infertile soiis were dominated by species with 'stress-tolerant' functional traits regardless of climate. Fertile soils were dominated by similar (stress tolerant) species in drier climates but by species with 'stress-intolerant' traits in wetter climates, thus creating greater functiional as well as species distinctiveness in wetter climates. Watering experiments in a single location confirmed that water availability interacts with soil fertility, via plant traits and competition, to determine the level of beta diversity between adjacent communities. This project trained Barbara Fernandez, a Latina, who is now a NSF and UC President's Postdoctoral Fellow, and Brian Anacker as doctoral students. It also trained Rachel Olliff, who is now a graduate student at UC Berkeley and an NSF Graduate Fellow, and many other (>20) undergraduate student assistants and interns . It assisted in the career development of Ellen Damschen, a recently tenured assoiciate professor at University of Wisconsin. It created a database of plant functional traits and commuinity data that have been used by >10 other researchers so far. It created an irrigation system that is now being used for studies of climate change. Finally, it contributed to KIDS (Kids Into Discovering Science), a program that brought >300 fifth grade students and their teachers to the McLaughlin UC Reserve to experience field science and natural history.
