STABLE ISOTOPES IN TREE RINGS AS PROXIES FOR WINTER PRECIPITATION CHANGES IN THE RUSSIAN ARCTIC OVER THE PAST 150 YEARS

We present results from an analysis of tree ring width and stable carbon and oxygen isotopes in tree ring cellulose of Siberian Spruce collected from remote forest islands in the northwestern Russian tundra. Ring width is often considered a proxy for summer temperatures. The aim of this pilot study was to test whether stable isotopes can provide additional information about climate during the growth of trees in this extreme environment. Comparison of delta C-13 and delta O-18 with observed meteorological data shows that there is a link between stable isotopes and winter precipitation. This may be explained by the strong influence that snow exerts on the isotopic composition of soil moisture during spring and early summer, when the new cellulose is formed. Our results show that winter precipitation in the study area was increasing from 1865-1900, and thereafter decreasing until similar to 1930. The 1960-1980 period was again rather humid, followed by a drying trend until 1990. The study highlights the potential of stable carbon and oxygen isotopes in tree rings as proxies for winter precipitation.