Objective Trying to explain the response of Chinese fir (Cunninghamia lanceolata) provenances to various climatic factors by analyzing the correlation between stable carbon isotope value in the cellulose of Chinese fir and the climatic factors.

Method The δ¹³C value of cellulose of 30 provenances was extracted and measured from the experimental forest farm of Chinese fir in Liuzhou, Guangxi. The δ¹³C value, the tree ring, the precipitation, the mean temperature, the minimum air temperature, the maximum air temperature, the mean relative humidity, the minimum relative humidity, the sunshine hours and the humidity index in the current year, the first year and the first two years were analyzed.

Result The variation range of δ¹³C value of tree ring of different Chinese fir provenances during 1987—2013 was -20.997‰－-25.910‰, showing strong first-order autocorrelation, the correlation coefficient was 0.181-0.866. The δ¹³C value of tree ring of different Chinese fir provenances was significantly and positively correlated with the mean temperature, the maximum temperature and the minimum temperature (p<0.05), and positively correlated with sunshine hours. There was a significantly negative correlation between the δ¹³C value and the mean and minimum relative humidity (p<0.01), but no obvious correlation with the precipitation and wetness index. The results of stepwise regression analysis showed that 26 out of the 30 Chinese fir provenances had linear relationship with the minimum relative humidity of the current year.

Conclusion The minimum relative humidity is the dominant climatic factor affecting the δ¹³C value of cellulose in the tree ring of Chinese fir provenances, which has little dependence on the precipitation. The response of δ¹³C in Chinese fir tree ring to climate factors has obvious lag effect. The study may provide reference for the cultivation and management of Chinese fir.