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Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-93
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
24 Jul 2017
Review status
This discussion paper is a preprint. A revision of this manuscript was accepted for the journal Climate of the Past (CP) and is expected to appear here in due course.
Modelling tree-ring cellulose δ18O variations of two temperature-sensitive tree species from North and South America
Aliénor Lavergne1, Fabio Gennaretti1, Camille Risi2, Valérie Daux3, Etienne Boucher4, Martine M. Savard5, Maud Naulier6, Ricardo Villalba7, Christian Bégin5, and Joël Guiot1 1Aix Marseille Université, CNRS, IRD, Collège de France, CEREGE, ECCOREV, Aix-en-Provence, France
2Laboratoirede Météorologie Dynamique, IPSL, UPMC, CNRS, Paris, France
3Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ, 91191 Gif-sur-Yvette, France
4Department of Geography and GEOTOP, Université du Québec à Montréal, Montréal, Canada
5Geological Survey of Canada, Natural Resources Canada, 490 rue de la Couronne, QC, G1K9A9, Canada
6Institut de Radioprotection et de Sureté Nucléaire (IRSN), PRP-ENV, SERIS/LRTE, Saint-Paul-lez-Durance, France
7Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales, IANIGLA-CONICET, Mendoza, Argentina
Abstract. Oxygen isotopes in tree-rings (δ18OTR) are widely used to reconstruct past climates. However, the complexity of climatic and biological processes controlling isotopic fractionation is not yet fully understood. Here, we use the MAIDENiso model to decipher the variability of δ18OTR of two temperature-sensitive species of relevant paleoclimatological interest (Picea mariana and Nothofagus pumilio) and growing at cold high-latitudes in North and South America. In this first modelling study on δ18OTR values in both northeastern Canada (53.86° N) and western Argentina (41.10° S), we specifically aim at: (1) evaluating the predictive skill of MAIDENiso to simulate δ18OTR values, (2) identifying the physical processes controlling δ18OTR by mechanistic modelling and, (3) defining the origin of the temperature signal recorded in the two species. Although the linear regression models used here to predict daily δ18O of precipitation (δ18OP) may need to be improved in the future, the resulting daily δ18OP values adequately reproduce observed (from weather stations) and simulated (by global circulation model) δ18OP series. The δ18OTR values of the two species are correctly simulated using the δ18OP estimation as MAIDENiso input, although some offset in mean δ18OTR levels is observed for the South American site. For both species, the variability of δ18OTR series is more likely linked to the effect of temperature on isotopic enrichment of the leaf water rather than on the isotopic composition of the source water. We show that MAIDENiso is a powerful tool for investigating isotopic fractionation processes but that the lack of a denser isotope-enabled monitoring network recording oxygen fractionation in the soil-vegetation-atmosphere compartments limits our capacity to decipher the processes at play. This study proves that the eco-physiological modelling of δ18OTR values is necessary to interpret the recorded climate signal more reliably.

Citation: Lavergne, A., Gennaretti, F., Risi, C., Daux, V., Boucher, E., Savard, M. M., Naulier, M., Villalba, R., Bégin, C., and Guiot, J.: Modelling tree-ring cellulose δ18O variations of two temperature-sensitive tree species from North and South America, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-93, in review, 2017.
Aliénor Lavergne et al.
Aliénor Lavergne et al.
Aliénor Lavergne et al.

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Short summary
Tree-rings are long-term recorders of past climate variations but the origin of the climate signals imprinted is difficult to interpret. Here, using a complex model we show that the temperature signal recorded in tree-rings from two species from North and South America is likely related to processes occurring at the leaf level. This result contribute to the quantitative interpretation of these proxies for their future exploitation for millennium-scale climate reconstructions.
Tree-rings are long-term recorders of past climate variations but the origin of the climate...
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