ALBERT

Description: Stable isotope ratios from tree rings are important proxies of past climate variations. We have access to a calendar-dated wood material from wood collected at glacier forefields and peat bog sites located in the Alps. They are of two species, larch (Larix decidua) and cembran pine (Pinus cembra). All the wood samples were collected at high altitudes in the Swiss and Tyrol Alps, they cover the whole Holocene period and belong to the Eastern Alpine Conifer Chronology Dataset (Nicolussi et al., 2009; doi:10.1177/0959683609336565). We analysed the δ13C, δ18O and δ2H isotope ratios of alpha cellulose obtained from blocks of 5 annual rings from 203 trees. Cellulose was extracted following the modified Jayme-Wise method (Boettger et al., 2007; doi:10.1021/ac0700023). The isotopes values were determined using conventional Isotope Ratio Mass Spectrometry (Isoprime 100) coupled to a pyrolysis unit (HEKAtech GmbH, Germany), which is similar to the previously used TC/EA (for technical details see (Leuenberger 2007). This approach was extended to measurements of non-exchangeable hydrogen of alpha-cellulose using the on-line equilibration method (Filot et al., 2006 (doi:10.1002/rcm.2743); Loader et al., 2015(doi:10.1021/ac502557x)). The results are reported in per mil (‰) relative to the Vienna Pee Dee Belemnite (VPDB) for carbon and to Vienna Standard Mean Ocean Water (VSMOW) for hydrogen and oxygen (Coplen 1994; doi:10.1351/pac199466020273). For all the δ13C values after 1000 CE we applied the factor described in Leuenberger (2007; doi:10.1016/S1936-7961(07)01014-7) to correct for the δ13C depletion of CO2 caused by the Industrial Revolution from about 1850 onwards (Leuenberger, 2007).