At least one third of the Earth's land experiences regular drought, and climate models suggest droughts will be more frequent and intense in the future. However, the biological processes that occur in ecosystems during the dry periods have generally only been studied by inference after studying what happens after rains return. Yet, important and surprising processes can occur during the dry season. For example, during the dry coastal California summer, soils of the grasslands are dry and the plants are dead, but the population size and mass of several important groups of soil microbes increase, even though their activity is apparently very limited. This unforeseen circumstance appears to result from a combination of the unique drought survival physiology of microorganisms, as well as disconnections in the very thin films of water that occur in dry soils that limit the diffusion of food they eat but also limit the movement of their predators. This project will evaluate changes in populations of key soil microbes through the dry summer in contrasting coastal California ecosystems (grassland, woodland, and chaparral), the physical and biological factors that regulate them, the dynamics of other related soil ecological processes, and their collective impacts on whole-ecosystem dynamics.
The docent program at the Sedgwick Reserve is the key element of the outreach program. The scientists of this project will run regular in-the-field training sessions for the docents and provide up-to-date materials on soils generally and on the results of this specific research project. Over 800 K-12 students and 100 adults have already visited the project site. In addition, both graduate and undergraduate students will be trained during this research.
