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| Titel |
A simple, single-substrate model to interpret intra-annual stable isotope signals in tree-ring cellulose |
| VerfasserIn |
J. Ogée, M. M. Barbour, L. Wingate, D. Bert, A. Bosc, M. Stievenard, C. Lambrot, M. Pierre, T. Bariac, R. C. Dewar |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250020812
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| Zusammenfassung |
| High-resolution intra-annual measurements of the carbon and oxygen stable isotope
composition of cellulose in annual tree rings (δ13Ccellulose and δ18Ocellulose, respectively)
reveal well-defined seasonal patterns that could contain valuable records of past climate and
tree function. Interpreting these signals is nonetheless complex because they not only record
the signature of current assimilates, but also depend on carbon allocation dynamics within the
trees. Here, we present a simple, single-substrate model for wood growth containing only 12
main parameters. The model is used to interpret an isotopic intra-annual chronology collected
in an even-aged maritime pine plantation growing in the South-West of France, where
climate, soil and flux variables were also monitored. The empirical δ13Ccellulose and
δ18Ocellulose exhibit dynamic seasonal patterns, with clear differences between years and
individuals, that are mostly captured by the model. In particular, the amplitude of
both signals is reproduced satisfactorily as well as the sharp 18O enrichment at the
beginning of 1997 and the less pronounced 13C and 18O depletion observed at
the end of the latewood. Our results suggest that the single-substrate hypothesis
is a good approximation for tree ring studies on Pinus pinaster, at least for the
environmental conditions covered by this study. A sensitivity analysis revealed that, in
the early wood, the model was particularly sensitive to the date when cell wall
thickening begins (twt). We therefore propose to use the model to reconstruct time
series of twt and explore how climate influences this key parameter of xylogenesis. |
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