Natural Resources, School of

 

Authors

B. E. Law, 328 Richardson Hall, College of Forestry, Oregon State University, Corvallis, OR 97331-5752, USA
E. Falge, Pflanzenökologie, Universität Bayreuth, 95440 Bayreuth, Germany
L. Gu, ESPM, University of California, Berkeley, CA 94704, USA
D. D. Baldocchi, ESPM, University of California, Berkeley, CA 94704, USA
P. Bakwin, NOAA/OAR, Climate Monitoring and Diagnostics Laboratory, 325 Broadway, Boulder, CO 80303, USA
P. Berbigier, INRA Centre de Bordeaux, Unite de Bioclimatologie, BP 81, 33833 Villenave d’ornon Cedex, France
K. Davis, Department of Soil, Water, and Climate, University of Minnesota, St. Paul, MN 55108, USA
A. J. Dolman, Alterra, P.O. Box 47, 6700 AA Wageningen, The Netherlands
M. Falk, Atmospheric Science Group, LAWR, UC Davis, 122 Hoagland Hall, Davis, CA 95616, USAFollow
J. D. Fuentes, Department of Environmental Science, University of Virginia, Charlottesville, VA, USA
A. Goldstein, ESPM, University of California, Berkeley, CA 94704, USA
A. Granier, Centre de Recherces de Nancy, Unite Ecophysiologie Forestieres, Equipe Bioclimatologie, 54280 Champenoux, France
A. Grelle, Department of Ecology and Environmental Research, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden
D. Hollinger, USDA Forest Service, 271 Mast Road, Durham, NH 03824, USA
I. A. Janssens, Department of Biology, University of Antwerpen, Wilrijk, Belgium
P. Jarvis, Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, King’s Buildings, Edinburgh EH9 3JU, UK
N. O. Jensen, Risoe National Laboratory, DK-4000 Roskilde, Denmark
G. Katul, School of the Environment, Duke University, Box 90328, Durham, NC 27708-0328, USA
K. Mahli, Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, King’s Buildings, Mayfield Road, Edinburgh EH9 3JU, UK
G. Matteucci, Department of Forest Environment and Resources, University of Tuscia, I-01100 Viterbo, Italy
T. Meyers, NOAA/ARL Atmospheric Turbulence and Diffusion Division, 456 South Illinois Avenue, Oak Ridge, TN 37831-2456, USA
R. Monson, Department of Environmental, Population, and Organismic Biology, University of Colorado, Campus Box 334, Boulder, CO 80309, USA
W. Munger, Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
W. Oechel, Department of Biology, San Diego State University, San Diego, CA, USA
R. Olson, Environmental Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
K. Pilegaard, Plant Biology and Biogeochemistry Department, Risoe National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark
K. T. Paw U, Atmospheric Science Group, LAWR, UC Davis, 122 Hoagland Hall, Davis, CA 95616, USA
H. Thorgeirsson, y Department of Environmental Research, Agricultural Research Institute, IS-112 Reykjavik, Iceland
R. Valentini, Department of Forest Environment and Resources, University of Tuscia, I-01100 Viterbo, Italy
Shashi Verma, University of Nebraska - LincolnFollow
T. Vesala, Department of Physics, University of Helsinki, P.O. Box 9, FIN-00014 Helsinki, Finland
K. Wilson, NOAA/ARL Atmospheric Turbulence and Diffusion Division, 456 South Illinois Avenue, Oak Ridge, TN 37831-2456, USA
S. Wofsy, Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA

Date of this Version

October 2002

Comments

Published in Agricultural and Forest Meteorology 113 (2002) 97–120.

Abstract

The objective of this research was to compare seasonal and annual estimates of COM2 and water vapor exchange across sites in forests, grasslands, crops, and tundra that are part of an international network called FLUXNET, and to investigating the responses of vegetation to environmental variables. FLUXNETs goals are to understand the mechanisms controlling the exchanges of CO2,water vapor and energy across a spectrum of time and space scales, and to provide information for modeling of carbon and water cycling across regions and the globe. At a subset of sites, net carbon uptake (net ecosystem exchange, the net of photosynthesis and respiration) was greater under diffuse than under direct radiation conditions, perhaps because of a more efficient distribution of non-saturating light conditions for photosynthesis, lower vapor pressure deficit limitation to photosynthesis, and lower respiration associated with reduced temperature. The slope of the relation between monthly gross ecosystem production and evapotranspiration was similar between biomes, except for tundra vegetation, showing a strong linkage between carbon gain and water loss integrated over the year (slopes = 3.4 g CO2/kg H2O for grasslands, 3.2 for deciduous broadleaf forests, 3.1 for crops, 2.4 for evergreen conifers, and 1.5 for tundra vegetation). The ratio of annual ecosystem respiration to gross photosynthesis averaged 0.83, with lower values for grasslands, presumably because of less investment in respiring plant tissue compared with forests. Ecosystem respiration was weakly correlated with mean annual temperature across biomes, in spite of within site sensitivity over shorter temporal scales. Mean annual temperature and site water balance explained much of the variation in gross photosynthesis. Water availability limits leaf area index over the long-term, and inter-annual climate variability can limit carbon uptake below the potential of the leaf area present.

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