American Geophysical Union Become an AGU Member
Subscribe to AGU Journals		 AGU Home AGU Publications

Read Full Article (file size: 1044910 bytes)    Cited by

GLOBAL BIOGEOCHEMICAL CYCLES, VOL. 17, NO. 2, 1070, doi:10.1029/2002GB001995, 2003

Partitioning net ecosystem carbon exchange into net assimilation and respiration using 13CO2 measurements: A cost-effective sampling strategy

J. Ogée

Laboratoire des Sciences du Climat et de l'Environnement, Commissariat à l'Energie Atomique-Saclay, Gif/Yvette Cedex, France


P. Peylin

Laboratoire de Biogéochimie Isotopique, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Pierre et Marie Curie, Paris, France


P. Ciais

Laboratoire des Sciences du Climat et de l'Environnement, Commissariat à l'Energie Atomique-Saclay, Gif/Yvette Cedex, France


T. Bariac

Laboratoire de Biogéochimie Isotopique, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Pierre et Marie Curie, Paris, France


Y. Brunet

Bioclimatologie, Institut National de la Recherche Agronomique-Bordeaux, Villenave d'Ornon, France


P. Berbigier

Bioclimatologie, Institut National de la Recherche Agronomique-Bordeaux, Villenave d'Ornon, France


C. Roche

Laboratoire de Biogéochimie Isotopique, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Pierre et Marie Curie, Paris, France


P. Richard

Laboratoire de Biogéochimie Isotopique, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Pierre et Marie Curie, Paris, France


G. Bardoux

Laboratoire de Biogéochimie Isotopique, Centre National de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Pierre et Marie Curie, Paris, France


J.-M. Bonnefond

Bioclimatologie, Institut National de la Recherche Agronomique-Bordeaux, Villenave d'Ornon, France


Abstract

The current emphasis on global climate studies has led the scientific community to set up a number of sites for measuring the long-term biosphere-atmosphere net CO2 exchange (net ecosystem exchange, NEE). Partitioning this flux into its elementary components, net assimilation (F A ), and respiration (F R ), remains necessary in order to get a better understanding of biosphere functioning and design better surface exchange models. Noting that F R and F A have different isotopic signatures, we evaluate the potential of isotopic 13CO2 measurements in the air (combined with CO2 flux and concentration measurements) to partition NEE into F R and F A on a routine basis. The study is conducted at a temperate coniferous forest where intensive isotopic measurements in air, soil, and biomass were performed in summer 1997. The multilayer soil-vegetation-atmosphere transfer model MuSICA is adapted to compute 13CO2 flux and concentration profiles. Using MuSICA as a “perfect” simulator and taking advantage of the very dense spatiotemporal resolution of the isotopic data set (341 flasks over a 24-hour period) enable us to test each hypothesis and estimate the performance of the method. The partitioning works better in midafternoon when isotopic disequilibrium is strong. With only 15 flasks, i.e., two 13CO2 nighttime profiles (to estimate the isotopic signature of F R ) and five daytime measurements (to perform the partitioning) we get mean daily estimates of F R and F A that agree with the model within 15–20%. However, knowledge of the mesophyll conductance seems crucial and may be a limitation to the method.

Received 27 September 2002; accepted 3 March 2003; published 20 June 2003.

Index Terms: 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 1615 Global Change: Biogeochemical processes (4805); 4805 Oceanography: Biological and Chemical: Biogeochemical cycles (1615).

Read Full Article (file size: 1044910 bytes)    Cited by

Citation: Ogée, J., P. Peylin, P. Ciais, T. Bariac, Y. Brunet, P. Berbigier, C. Roche, P. Richard, G. Bardoux, and J.-M. Bonnefond (2003), Partitioning net ecosystem carbon exchange into net assimilation and respiration using 13CO2 measurements: A cost-effective sampling strategy, Global Biogeochem. Cycles, 17(2), 1070, doi:10.1029/2002GB001995.