Isotopic composition (δ13C, δ18O) in wood and cellulose of Siberian larch trees for early Medieval and recent periods

We related tree ring width (TRW) and isotopic composition (delta C-13, delta O-18) of wood and cellulose from four larch trees (Larix cajanderi Mayr.) to climate parameters. The material was sampled in northeastern Yakutia [70 degrees N-148 degrees E] for the recent (AD 1880-2004) and early Medieval (AD 900-1000) periods. During the recent period June, July, and August air temperatures were positively correlated with delta C-13 and delta O-18 of wood and cellulose, while July precipitation was negatively correlated. Furthermore, the vapor pressure deficit (VPD) of July and August was significantly correlated with delta C-13 of wood and cellulose, but VPD had almost no influence on delta O-18. Comparative analyses between mean isotope values for the (AD 900-1000) and (AD 1880-2004) periods indicate similar ranges of climatic conditions, with the exception of the period AD 1950-2004. While isotopic ratios in cellulose are reliably related to climatic variables, during some periods those in whole wood showed even stronger relationships. Strong positive correlations between delta O-18 of cellulose and Greenland ice-core (GISP2) data were detected for the beginning of the Medieval period (r = 0.86; p < 0.05), indicating the reliability of isotope signals in tree rings for large-scale reconstructions.