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TitreModelling tree ring cellulose ?18O variations in two temperature-sensitive tree species from North and South America
AuteurLavergne, A; Gennaretti, F; Risi, C; Daux, V; Boucher, E; Savard, M M; Naulier, M; Villalba, R; Bgin, C; Guiot, J
SourceClimate of the Past vol. 13, 11, 2017 p. 1515-1526,
Séries alt.Ressources naturelles Canada, Contribution externe 20182516
ÉditeurCopernicus GmbH
Documentpublication en série
Mediapapier; en ligne; numérique
ProgrammeSources, Géosciences environnementales
Diffusé2017 11 10
Résumé(disponible en anglais seulement)
Oxygen isotopes in tree rings (?18OTR) 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 in ?18OTR of two temperature-sensitive species of relevant palaeoclimatological interest (Picea mariana and Nothofagus pumilio) and growing at cold high latitudes in North and South America. In this first modelling study on ?18OTR 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 ?18OTR values, (2) identifying the physical processes controlling ?18OTR 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 ?18O of precipitation (?18OP) may need to be improved in the future, the resulting daily ?18OP values adequately reproduce observed (from weather stations) and simulated (by global circulation model) ?18OP series. The ?18OTR values of the two species are correctly simulated using the ?18OP estimation as MAIDENiso input, although some offset in mean ?18OTR levels is observed for the South American site. For both species, the variability in ?18OTR series is primarily linked to the effect of temperature on isotopic enrichment of the leaf 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 ?18OTR values is necessary to interpret the recorded climate signal more reliably. © 2017 Author(s).