DISSERTATION RESEARCH: Exploring the Impacts of Long-Term Warming on Arctic Soils: Linking Microbial Communities with Seasonal Biogeochemical Dynamics.

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

The total soil organic carbon (SOC) in the northern permafrost zone is estimated to be more than twice as much C as is in the atmosphere. The accumulation of this SOC is driven by the cold climate limiting decomposition. Climate models predict that the Arctic will warm over the next century, therefore accelerating microbial decomposition of SOC is one of the most significant potential greenhouse gas release feedbacks from terrestrial ecosystems to the atmosphere. Winter snow cover and spring thaw are particularly important in influencing decomposition. Few studies, however, have explored how long-term warming will affect the seasonality of soil biogeochemical dynamics. To address this knowledge gap, this research project uses a greenhouse experiment initiated in 1988 at the Toolik, AK Long Term Ecological Research site to explore the consequences of long-term warming on Arctic soil microbial dynamics and nutrient cycling through repeated sampling across seasons and soil horizons. Bacterial and fungal communities? DNA will be studied, to characterize phylogenetically how different organisms respond to long-term warming across seasons and soil horizons. This work is being used to develop and parameterize a mechanistic model of tundra soils? responses to warming. Broader impacts: The data and model that grows from them are part of a multi-institute collaborative effort supported by the Arctic System Science Program's ?Changing Seasonality in the Arctic System initiative.? The model directly links the structure and activity of the Arctic microbial community to C and nutrient cycling, increasing our ability to predict how biogeochemical cycling in this system will respond to rapid climate warming. Additionally, any pyrosequencing-derived sequences generated through this project will be added into the NIH GenBank database. In addition to scientific collaborations, this project will foster the development of several students in the biogeochemical sciences, including two female undergraduates and a minority high school student, as well as supported participation in several science outreach projects targeted to the local K-12 community. The NSF DDIG grant will enhance the completion of a doctoral dissertation by a female scientist, as well as promoting continued outreach efforts in global change science education and cross-disciplinary research.