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


Jingfeng Xiao

Qianlai Zhuang

Beverly Law

Dennis Baldocchi

Jiquan Chen

Andrew Richardson

Jerry Melillo

Kenneth Davis

David Hollinger

Sonia Wharton

Ram Oren

Asko Noormets

Marc Fischer

Shashi Verma

David Cook

Ge Sun

Steve McNulty

Steven Wofsy

Paul Bolstad

Sean Burns

Peter Curtis

Bert Drake

Matthias Falk

David Foster

Lianhong Gu

Julian Hadley

Gabriel Katul

Marcy Litvak

Siyan Ma

Timothy Martin

Roser Matamala

Tilden Meyers

Russell Monson

William Munger

Walter Oechel

Kyaw Paw

Hans Schmid

Russell Scott

Gregory Starr

Andrew Suyker


+36 more
Publication Type:
Journal Article
Year of Publication:
Secondary Title:
Agricultural and Forest Meteorology


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.