Oxygen and carbon isotopic record of climatic variability in tree ring cellulose (Picea abies):: An example from central Switzerland (1913-1995)

Stable isotopic data from terrestrial records spanning the last century provide an unique opportunity to test and calibrate how these systems respond to recent climatic change. Here we present an annual oxygen and carbon isotope record covering the period from 1913 to 1995 measured in tree ring cellulose of spruce trees (Picea abies) from central Switzerland. We compare these results with historical low- and high-frequency instrumental data. The isotopic data show high-frequency and spectral correlations, although long-term trends appear to be dissimilar. Our approach also uses constructed time series of these isotopic data with the different climate variables and demonstrates that not all parameters affect the record in the same manner. Additionally, we tested the trees' ability to record the isotopic composition of precipitation and thus changes in temperature and atmospheric circulation. Over the last 23 years, changes of up to 2 parts per thousand in the delta(18)O value of precipitation have been recorded in the nearby Bern Global Network for Isotopes in Precipitation station, and our tree ring isotopic record shows similar changes as a result of moisture uptake during the growing season. Naturally, all biologic systems react differently to environmental perturbations, and correlation with other records will provide a means to validate how well these systems reflect actual climatic changes.