Latitudinal patterns of magnitude and interannual variability in net ecosystem exchange regulated by biological and environmental variables

Authors

Wenping Yuan, University of OklahomaFollow
Yiqi Luo, University of Oklahoma
Andrew D. Richardson, University of New HampshireFollow
Ram Oren, Duke University
Sebastiaan Luyssaert, University of Antwerpen, Belgium
Ivan A. Janssens, University of Antwerpen, Belgium
Reinhart Ceulemans, University of Antwerpen, Belgium
Xuhui Zhou, University of Oklahoma
Thomas Grünwald, Technische Universität Dresden, Germany
Marc Aubinet, Faculte´ des Sciences Agronomiques de Gembloux,
Christian Berhofer, Technische Universität Dresden, Germany
Dennis D. Baldocci, University of California, Berkeley
Jiquan Chen, University of ToledoFollow
Allison L. Dunn, Worcester State College, MA
Jared L. DeForest, Ohio University
Danilo Dragoni, Indiana University
Allen H. Goldstein, University of California, Berkeley
Eddy Moors, Alterra, The Netherlands,
J. William William Munger, Harvard University
Russell K. Monson, University of Colorado
Andrew E. Suyker, University of Nebraska-LincolnFollow
Gregory Starr, University of Alabama,
Russell L. Scott, USDA Agricultural Research Service, Tucson, AZ
John Tenhunen, University of Bayreuth, Germany
Shashi Verma, University of Nebraska - LincolnFollow
Timo Vesala, University of Helsinki, Finland
Steven C. Wofsy, Harvard University

Date of this Version

2009

Comments

Published in Global Change Biology (2009) 15, 2905–2920, doi: 10.1111/j.1365-2486.2009.01870.x

Abstract

Over the last two and half decades, strong evidence showed that the terrestrial ecosystems are acting as a net sink for atmospheric carbon. However the spatial and temporal patterns of variation in the sink are not well known. In this study, we examined latitudinal patterns of interannual variability (IAV) in net ecosystem exchange (NEE) of CO₂ based on 163 site-years of eddy covariance data, from 39 northern-hemisphere research sites located at latitudes ranging from ~29°N to ~ 64°N. We computed the standard deviation of annual NEE integrals at individual sites to represent absolute interannual variability (AIAV), and the corresponding coefficient of variation as a measure of relative interannual variability (RIAV). Our results showed decreased trends of annual NEE with increasing latitude for both deciduous broadleaf forests and evergreen needleleaf forests. Gross primary production (GPP) explained a significant proportion of the spatial variation of NEE across evergreen needleleaf forests, whereas, across deciduous broadleaf forests, it is ecosystem respiration (Re). In addition, AIAV in GPP and Re increased significantly with latitude in deciduous broadleaf forests, but AIAV in GPP decreased significantly with latitude in evergreen needleleaf forests. Furthermore, RIAV in NEE, GPP, and Re appeared to increase significantly with latitude in deciduous broadleaf forests, but not in evergreen needleleaf forests. Correlation analyses showed air temperature was the primary environmental factor that determined RIAV of NEE in deciduous broadleaf forest across the North American sites, and none of the chosen climatic factors could explain RIAV of NEE in evergreen needleleaf forests. Mean annual NEE significantly increased with latitude in grasslands. Precipitation was dominant environmental factor for the spatial variation of magnitude and IAV in GPP and Re in grasslands.