Soil carbon and greenhouse gases in restored mountain meadows
Meadows in the Sierra Nevada are strong sinks of soil carbon. Yet a century of disturbance has resulted in incised stream channels, dry soil, and a loss of soil carbon. Recently, the state of California passed Cap-and-Trade legislation. Therefore, the California Air Resources Board and the Department of Fish and Wildlife wanted to know if restoration of meadows increases soil carbon storage, and if that stored carbon could be used to pay for the restoration work using the carbon marketplace. We are working with partners at Plumas Corporation, CalTrout, the University of California, Merced, and many more to address these questions. Between 2015 and 2018, we will assess soil carbon and greenhouse gas dynamics in mountain meadows before and after restoration, unrestored comparison meadows, and meadows that were restored up to 15 years ago. We will consider whether soil methane or nitrous oxide fluxes contribute to or offset increased soil carbon sequestration potential. We hope to generate models that can predict changes in soil carbon in restored meadows.
Rates and mechanisms of soil methane dynamics in arid environments
Methane is the second-most important greenhouse gas contributing to climate change. Anaerobic microbial activity in wet soils produces methane, but specialized microbes in well-drained soils actually consume it. Though arid and semiarid soils cover one-third of the Earth's land surface, we know very little about the mechanisms that control methane uptake in very dry soils. The goal of this research is to assess rates of methane uptake in dry soils, and identify the mechanisms that control methane uptake. We hope to peel back the surface of a very dark hole in aridland biogeochemistry by combining field and laboratory studies to assess methane fluxes in the Great Basin.
Tropical biogeochemistry: nitrogen fixation, secondary succession, and global change
Is this general enough? I'm fascinated by plant-soil feedbacks in tropical forest, and especially in secondary forest, which is becoming a major fraction of remaining tropical forest. Secondary forest isn't second-rate: in fact, it could be critical to the biogeochemical functioning of the remaining forested regions in the tropics. Understanding how these forests function and change is going to be a major concern for many developing countries in the years to come, as land use change intensifies. To date, this tropical research has been the product of collaborations begun during my postdoctoral research with my mentor Cory Cleveland, his Ph.D. student (and my former undergraduate assistant) Megan Nasto, and his former postdocs Sasha Reed and Silvia Alvarez. But this list leaves off so many other stellar, brilliant folks, so be sure to ask me about how great my fellow tropical ecologists are!
Plant-soil feedbacks and restoration of old fields in Nevada
Large swathes of lowlying land in Nevada has been used for alfalfa production since the turn of the 20th century. In some regions, this land is being taken out of production. Effectively reverting these former alfalfa fields to native vegetation may require understanding the dramatic changes a century of alfalfa production has had on the soil. In this research, we are attempting to identify the soil characteristics that are most likely to be associated with restoration success and identify what the effect of restoration is on the resistance and resilience of soil processes.
Effect of piñon-juniper fuels management on vegetation and soils in the Great Basin
In the central Great Basin, an effort to improve sagebrush habitat has required the harvest of piñon and juniper trees. Typically, the tree material is either masticated or lopped and scattered on site. We seek to quantify the effects that these slash treatments have on the soil microenvironment and the success of existing and emergent vegetation.