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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.
Copyright 2003 by the American Geophysical Union.
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