PRINCIPAL INVESTIGATOR: Stan D. Wullschleger
PARTICIPATING STAFF: Charles T. Garten, Robin L. Graham, Melanie A. Mayes, Wilfred M. Post, Chris W. Schadt
PROJECT START DATE: October 1999
PROJECT END DATE: September 2011
SPONSOR: US DOE, Office of Science, Biological and Environmental Research
PARTNERS: Argonne National Laboratory, Boise State University , National Renewable Energy Laboratory, Ohio State University, Pacific Northwest National Laboratory, Texas A&M University , USDA Land Management & Water Conservation Research Unit, University of California-Davis
PROJECT WEBSITE: http://csite.eds.ornl.gov
PROJECT DESCRIPTION
The Carbon Sequestration in Terrestrial Ecosystems (CSiTE) project conducts research to acquire fundamental knowledge that underpins the implementation of soil carbon sequestration. Research is based on the premise that identifying and understanding the basic mechanisms controlling sequestration across managed and unmanaged ecosystems is fundamental to developing approaches for enhancing carbon capture and long-term storage in soils. The goal is to discover and characterize links among physical, chemical, and biological processes that influence (1) how quantity and quality of plant biomass input, including those derived from genotypic variation, influence soil carbon storage; (2) how soil structural properties control carbon lifetimes in managed storage pools; (3) how microbial communities respond to litter inputs and how community function influences stabilization of soil carbon; and (4) how humification chemistry and intrasolum carbon transport processes are influenced by soil chemical and physical characteristics.
Knowledge gained from field and laboratory studies is used to refine our representation of processes in models, which are then used to generate new hypotheses in a highly iterative manner. Integration of research is achieved by coordinating research conducted both in the laboratory and at two field sites where land-use practices, experimental manipulations, or chronosequences afford opportunities to observe how climate, soil, and land-use impacts on soil carbon and understand the system-level consequences of potentially implementing sequestration strategies over relevant temporal and spatial scales. Project participants represent a multi-lab collaboration among plant, microbial, and soil scientists at ORNL, Argonne National Laboratory, Boise State University , National Renewable Energy Laboratory, Ohio State University, Pacific Northwest National Laboratory, Texas A&M University , USDA Land Management & Water Conservation Research Unit, and University of California-Davis .
SIGNIFICANCE
Results from CSiTE experiments will contribute to the development of sustainable technologies to enhance carbon sequestration and quantify the potential of these technologies for mitigating climate change. Furthermore, because CSiTE utilizes switchgrass and poplar ecosystems managed for cellulosic biomass production as a testbed, CSiTE research findings will have immediate relevance to the scientific advancement of an important technology for mitigating climate change – bioenergy.
INTERESTING FINDINGS
Soil carbon is regulated by the balance between inputs and outputs. Roots are a significant input of organic matter to soils, but they also regulate output by stimulating microbial activity through the release of easily degradable exudates such as sugars, amino acids and organic acids. The interaction between these opposing processes, and the resulting contribution of inputs and outputs to soil carbon accumulation are uncertain. Scientists at ORNL, the University of Tennessee, and Boise State University used controlled additions of root exudates to microcosms to ascertain how labile carbon inputs regulate decomposition of harder to degrade soil and litter carbon sources and shape soil microbial communities that drive decomposition. Results show that labile soil carbon inputs can regulate decomposition of more recalcitrant organic matter by controlling the activity and relative abundance of fungi and bacteria. This result supports the “priming” theory that has suggested these labile inputs affect decomposition by providing fuel that jump starts the microbial community, which then allows them to use more of the harder to degrade soil and litter carbon sources. Future work will investigate how different types of root-specific compounds alter soil organic matter decomposition, what the role of microbial abundance versus community structure is in these processes, and how different types on perturbations may influence these patterns across ecosystems.
