Assessing net ecosystem carbon exchange of U.S. terrestrial ecosystems by integrating eddy covariance flux measurements and satellite observations

TitleAssessing net ecosystem carbon exchange of U.S. terrestrial ecosystems by integrating eddy covariance flux measurements and satellite observations
Publication TypeJournal Article
Year of Publication2011
AuthorsXiao, Jingfeng, Zhuang Qianlai, Law Beverly E., Baldocchi Dennis D., Chen Jiquan, Richardson Andrew D., Melillo Jerry M., Davis Kenneth J., Hollinger David Y., Wharton Sonia, Oren Ram, Noormets Asko, Fischer Marc L., Verma Shashi B., Cook David R., Sun Ge, McNulty Steve, Wofsy Steven C., Bolstad Paul V., Burns Sean P., Curtis Peter S., Drake Bert G., Falk Matthias, Foster David R., Gu Lianhong, Hadley Julian L., Katul Gabriel G., Litvak Marcy, Ma Siyan, Martin Timothy A., Matamala Roser, Meyers Tilden P., Monson Russell K., J. Munger William, Oechel Walter C., U. Paw Kyaw Tha, Schmid Hans Peter, Scott Russell L., Starr Gregory, Suyker Andrew E., and TORN MARGARET S.
JournalAgricultural and Forest Meteorology
Volume151
Pagination60 - 69
Date Published1/2011
ISSN01681923
Keywordscarbon sink, disturbance, drought, eddy covariance, interannual variability, MODIS, net ecosystem carbon exchange, U.S.
Abstract

More accurate projections of future carbon dioxide concentrations in the atmosphere and associated climate change depend on improved scientific understanding of the terrestrial carbon cycle. Despite the consensus that U.S. terrestrial ecosystems provide a carbon sink, the size, distribution, and interannual variability of this sink remain uncertain. Here we report a terrestrial carbon sink in the conterminous U.S. at 0.63 pg C yr-1 with the majority of the sink in regions dominated by evergreen and deciduous forests and savannas. This estimate is based on our continuous estimates of net ecosystem carbon exchange (NEE) with high spatial (1 km) and temporal (8-day) resolutions derived from NEE measurements from eddy covariance flux towers and wall-to-wall satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the U.S. terrestrial ecosystems could offset a maximum of 40% of the fossil-fuel carbon emissions. Our results show that the U.S. terrestrial carbon sink varied between 0.51 and 0.70 pg C yr-1 over the period 2001–2006. The dominant sources of interannual variation of the carbon sink included extreme climate events and disturbances. Droughts in 2002 and 2006 reduced the U.S. carbon sink by \~{}20% relative to a normal year. Disturbances including wildfires and hurricanes reduced carbon uptake or resulted in carbon release at regional scales. Our results provide an alternative, independent, and novel constraint to the U.S. terrestrial carbon sink.

DOI10.1016/j.agrformet.2010.09.002