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Non-pooled oak stable isotopes reveal enhanced climate sensitivity compared to ring widths

Michal Rybníček*, Tomáš Kolář, Alexander Ač, Jan Balek, Eva Koňasová, Miroslav Trnka, Otmar Urban, Ulf Büntgen

*Corresponding author:

ABSTRACT: Multi-centennial to millennial-long oak ring width chronologies from living and relict wood are frequently used for climate reconstructions, but the amount of explained hydroclimatic variation remains relatively small. Although stable carbon and oxygen isotopic ratios (δ13C and δ18O values) in tree rings may offer enhanced climate sensitivity, our understanding of their paleoclimatic sensitivity is still limited by the general lack of well-replicated and high-resolution datasets. Here, we assess the temperature, precipitation and drought signal of annual δ13C, δ18O values and tree-ring width (TRW) measurements from 21 oaks that were growing under different ecological settings in the Czech Republic. Compared to the overall low climate sensitivity of TRW, the δ13C and δ18O chronologies reveal significant positive and negative correlations with March–August mean temperature and hydroclimate (p <0.051901-2018), respectively. Additional tests on the effect of sample size demonstrate robust climate sensitivity of the isotopic chronologies when non-pooled alpha cellulose from the latewood of at least six individual oaks was used. Our study suggests that oak stable isotopes are possibly the best high-resolution paleoclimatic proxy for the central European lowlands, as well as any other temperate habitat where the species has been used historically as construction timber, and where traditional tree-ring parameters, such as TRW, tend to fail.