Reconstruction of past precipitation δ18O using tree-ring cellulose δ18O and δ13C: A calibration study near Lac dʹAnnecy, France

Two sets of living oaks (Quercus R.) growing under different hydrological situations were sampled near Lac dʹAnnecy, France. The stable isotope composition of the latewood cellulose was analysed in terms of oxygen and carbon isotopic composition for the period 1971–2001 and compared to the nearby monthly meteorological (temperature, relative humidity) and isotopic composition of precipitation records. A linear regression shows that 60% of the cellulose oxygen isotopic composition inter-annual variations are due to changes in precipitation isotopic composition and relative humidity. The small slope between cellulose versus precipitation oxygen isotopic composition suggests a significant contribution of local continental recycling and questions the common assumption that vapour oxygen isotopic composition is at equilibrium with precipitation isotopic composition in Europe during the growing season. Finally, the combined use of tree-ring oxygen and carbon isotopic composition records enables to account for leaf water enrichment due to stomata stress and to provide a reconstruction (R2 = 0.64) of the summer precipitation isotopic composition.