Conditional flux analysis and stable isotopes
Matthias J. Zeeman1, Alexander Knohl1, Nina Buchmann1, Patrick Sturm1, Christoph Thomas2
1 ETH Zurich, Switzerland
2 Oregon State University, USA
2 Oregon State University, USA
P39 in Poster presentations
We propose to investigate to what extend conditional flux analysis can benefit from the addition of stable isotope information. Stable isotopes have been recognized for their potential as process tracer, and could add an extra dimension to the conditional flux concept, which aims at directly quantifying component fluxes and identifying their sources. Differences in 13C abundance in carbon dioxide can be used to distinguish assimilation or respiration sources, whereas the 18O abundance expresses differences in water exchange, for instance between canopy and soil. Lending to recent advances in measurement technology, stable isotopes can now be measured at high temporal resolutions (10Hz) required for commonly applied micrometeorological methods such as the eddy-covariance technique, or related conditional flux methods. We will present current ideas on how the conditional flux method, as recently proposed by Thomas et al. (2008) to perform daytime flux partitioning at the ecosystem level, can be refined by stable isotope analysis (13C and 18O) of carbon dioxide as additional dimension for identification of fluxes.
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