Latitudinal patterns of magnitude and interannual variability in net ecosystem exchange regulated by biological and environmental variables |
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| Authors: | WENPING YUAN YIQI LUO ANDREW D RICHARDSON RAM OREN SEBASTIAAN LUYSSAERT IVAN A JANSSENS REINHART CEULEMANS XUHUI ZHOU THOMAS GRÜNWALD MARC AUBINET CHRISTIAN BERHOFER DENNIS D BALDOCCHI JIQUAN CHEN ALLISON L DUNN JARED L DEFOREST DANILO DRAGONI ALLEN H GOLDSTEIN EDDY MOORS J WILLIAM MUNGER RUSSELL K MONSON ANDREW E SUYKER GREGORY STARR RUSSELL L SCOTT JOHN TENHUNEN SHASHI B VERMA TIMO VESALA STEVEN C WOFSY |
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| Institution: | Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA,;Complex Systems Research Center, University of New Hampshire, Durham, NH 03824, USA,;Nicholas School of the Environment and Earth Sciences, PO Box 90328, Duke University, Durham, NC 27708, USA,;Department of Biology, University of Antwerpen, Universiteitsplein 1, B-2610 Wilrijk, Belgium,;Institute of Hydrology and Meteorology, Technische Universität Dresden, Pienner Str. 23, D-01737 Tharandt, Germany,;Unitéde Physique, Facultédes Sciences Agronomiques de Gembloux, B-50 30 Gembloux, Belgium,;Department of Environmental Science, Policy, &Management, University of California, Berkeley, CA 94720, USA,;Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, USA,;Department of Physical and Earth Sciences, Worcester State College, 486 Chandler Street, Worcester, MA 01602, USA,;Department of Environmental and Plant Biology, Ohio University, Athens, OH 45701, USA,;Department of Geography, Indiana University, Bloomington, IN 47405, USA,;Alterra, PO Box 47, 6700 AA Wageningen, The Netherlands,;School of Engineering and Applied Sciences, Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA,;Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA,;School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68583, USA,;Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA,;USDA Agricultural Research Service, 2000 E. Allen Road, Tucson, AZ 85719, USA,;Department of Plant Ecology, University of Bayreuth, Universitaetstrasse 30, 95440 Bayreuth, Germany,;Department of Physics, PO Box 64 FIN-00014, University of Helsinki, Finland |
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| 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. |
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| Keywords: | ecosystem respiration eddy covariance gross primary production interannual variability latitudinal pattern net ecosystem exchange |
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