Based on cross-dating tree ring age from Tianmu Mountain, Zhejiang Province, theδD of each tree ring nitrocellulose was measured and then theδ D annual time series was established. Using meteorological data from Tianmu Mountain Observatory, the responds ofδ D of tree ring to climatic factors were analyzed. The results suggest that theδ D time series of the tree ring correlates well with climatic conditions, primarily with precipitation of the second half of each year, average annual air temperature and average annual maximum air temperature. The reconstructed maximum winter air temperature by theδ D of tree ring is in good correlation with local instrumental data. The low-frequency variations of reconstructed mean maximum air temperature of the winter in Tianmu Mountain corroborate with the temperature change in a large special scale. Tianmu Mountain is located in winter monsoon sensitive zone, thus the influence of winter temperature on tree growth is quite obvious. The results in this paper suggest thatδ D of tree ring is an effective proxy for winter temperature in non-limited regions.
The annual series of δ13C were measured in tree rings of three Cryptomeria fortunei disks （OF-1, OF-2, and OF- 3） collected from West Tianmu Mountain, Zhejiang Province, China, according to cross-dating tree ring ages. There was no obvious decreasing trend of the δ13C annual time series of CF-2 before 1835. However, from 1835 to 1982 the three tree ring δ13C annual series exhibited similar decreasing trends that were significantly （P ≤ 0.001） correlated. The distribution characteristics of a scatter diagram between estimated δ13C series of CF-2 from modeling and the atmospheric CO2 concentration extracted from the Law Dome ice core from 1840 to 1978 were analyzed and a curvilinear regression equation for reconstructing atmospheric CO2 concentration was established with R2 = 0.98. Also, a test of independent samples indicated that between 1685 and 1839 the reconstructed atmospheric CO2 concentration .using the δ13C series of CF-2 had a close relationship with the Law Dome and Siple ice cores, with a standard deviation of 1.98. The general increasing trend of the reconstructed atmospheric CO2 concentration closely reflected the 10ng-term variation of atmospheric CO2 concentration recorded both before and after the Industrial Revolution. Between 1685 and 1840 the evaluated atmospheric CO2 concentration was stable, but after 1840 it exhibited a rapid increase. Given a longer δ13C annual time series of tree rings, it was feasible to rebuild a representative time series to describe the atmospheric CO2 concentration for an earlier period and for years that were not in the ice core record.
Based on cross-dating tree rings from the Tianmu Mountain, Zhejiang Province, the tree rings α-cellulose δ13C time series was measured. By spectrum analysis, the variation of tree-ring δ13C sequence shows a quasi periodicity of 4.4 years, which is coincident with the standard cycle of El Nino. After removing the long-term decrease trend of the δ13C variation related to atmospheric CO2 concentration, the response of the δ13C to climate elements was analyzed using meteorology data from a nearby weather station. The results suggest that there is a distinct relativity between high-frequency variation of tree ring δ13C series and seasonal climate parameters, e.g. temperature and precipitation, with a significant time-lag effect. In addition, the high frequency also reflects the strength change of the East Asian Monsoon. The multiple regression method was employed to reconstruct the historical climate, and to analyze the climate change and trend in the last 160 years in the northern Zhejiang Province.
