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Coupling the effects of management and climate on carbon and water fluxes in the forests of the eastern U.S. and the Peoples Republic of China
PARTNERS: University of Toledo Landscape Ecology and Ecosystem Science Lab, Members of the U.S.-China Carbon Consortium
SUMMARY: Carbon dioxide emissions from natural and anthropogenic sources are thought to contribute to warmer climate and more frequent extremes in temperature and precipitation. The increased variation in climate may alter ecosystem carbon exchange dynamics by stimulating respiration and suppressing assimilation, leading to lower long-term carbon sequestration. Likewise, carbon stocks in managed forests are vulnerable to climate- and disturbance-induced release of CO2. The disturbance of soil by machinery, increased aeration because of drainage and plowing, and altered moisture regime may expose soil carbon pools that in a natural system could be considered long-term storage, making them available for microbial decomposition. Eddy covariance offers a monitoring tool that can detect changes in carbon exchange at ecosystem to landscape level, and over a wide range of time scales – from individual weather events of a few days to decade-long systematic shifts in climate. Furthermore, the high frequency of measurements (ecosystem net carbon, water and energy budgets are typically calculated at 30-minute intervals, 365 days a year) allows inference of the mechanisms behind the changes in carbon and water exchange. Coupled with traditional Forest Inventory and Analysis (FIA) datasets, eddy covariance measurements provide a powerful tool to assess ecosystem health, their capacity to store and release carbon, and validate large-scale biogeochemical circulation models and remote sensing products.
The primary goal of this study is to assess the causal relationships between management or disturbance regimes and the environmental controls of biosphere-atmosphere exchange of carbon and water. The overall objective is to measure and model the coupling effects of forest management and changing climate on CO2 and H2O fluxes in eastern forests of the U.S. and China. This study would be among the first to provide strong quantitative information concerning carbon exchange at disturbed ecosystems over their successional stages. Results learned from three new flux sites will be compared with data from eight other existing sites toward a synthesis of decoupling the effects of climate and management. These results will further advance current management efforts in the region and the world, where carbon credits are seriously being considered in resources management. The duration for this research study is estimated at five to ten years and will result in several publications and conference presentations with international significance.
EFETAC'S ROLE: Researchers have expanded investigations into carbon, water, and nutrient cycling and interactions in the coastal plain, building on the record of these Forest Service-supported flux sites. Funding for the new work comes from Department of Energy, and several grants have been submitted to the National Science Foundation. Researchers also collaborate with a number of people from Virginia Tech, University of Florida, Environmental Protection Agency, University of North Carolina-Chapel Hill and other Forest Service branches by providing long-term ground truthing at physiological, ecosystem, and hydrologic levels to various satellite validations, land surface models, and regional upscaling efforts.
STATUS: Ongoing
PROGRESS: Results from this project show (1) that soils may be losing carbon, i.e., long-term sequestration comes into question, and (2) that current productivity levels are water-expensive, i.e., with more frequent or more severe droughts in the future, their ability to sequester carbon can be dramatically reduced. Although these aspects have not been quantified on a national scale (efforts are underway, though), the impacts on forest productivity and carbon sequestration potential are far greater than any insect outbreak or disease could cause.
Recent publications that discuss the results of this study:
Domec, J.C., J.S. King, A. Noormets, E.A. Treasure, M.J. Gavazzi, G. Sun, and S.G. McNulty. 2010. Hydraulic redistribution of soil water affects whole stand evapotranspiration and net ecosystem carbon exchange. New Phytologist New Phytologist 187:171-183. (PDF)
Domec, J.C., A. Noormets, J.S. King, G. Sun, S.G. McNulty, M.J. Gavazzi, J.L. Boggs, and E.A. Treasure. 2009. Decoupling the influence of leaf and root hydraulic conductances on stomatal conductance and its sensitivity to vapor pressure deficit as soil dries in a drained loblolly pine plantation. Plant, Cell & Environment 32:980-991. (PDF)
Noormets, A., M.J. Gavazzi, S.G. McNulty, J.C. Domec, G. Sun, J. King, and J. Chen. 2010. Response of carbon fluxes to drought in a coastal plain loblolly pine forest. Global Change Biology 16:272-287. (PDF)
Sun, G., A. Noormets, M. Gavazzi, S.G. McNulty, J. Chen, J.C. Domec, J.S. King, D.M. Amatya, and R.W. Skaggs. 2010. Energy and water balance of two contrasting loblolly pine plantations on the Lower Coastal Plain of North Carolina, USA. Forest Ecology and Management 259:1299-1310. (PDF)
A slideshow that describes this study is available.
Many additional papers and presentations have also been produced as part of this project.
LINKS:
University of Toledo Landscape Ecology and Ecosystem Science Lab
U.S.-China Carbon Consortium (USCCC)
CONTACT: Asko Noormets, North Carolina State University Department of Forestry and Environmental Resources, anoorme@ncsu.edu or 919-515-7040
Updated December 2011
