Responses of Picea meyeri to Climatic Factors Revealed by Tree Ring Isotopes and Water Use Efficiency on Luya Mountain of North-Central China

Along with tree ring width, carbon isotopes are also good proxies for climate change. Water use efficiency (WUE) can be calculated more quickly and accurately based on carbon isotopes. In this study, according to the principle of dendroclimatology, the sequence of delta C-13 and WUE of tree rings of Picea meyeri are built. Pearson correlation analysis and multiple regression analysis are used to explore the response of carbon stable isotopes of Picea meyeri to climate change, which revealed the relationship between delta C-13 of Picea meyeri and climatic factors. Based on delta C-13, we calculated the WUE of Picea meyeri and analyzed its response to climate change. The main conclusions are as follows: (1) The delta C-13 of Picea meyeri decreases year-by-year from 1957 to 2020, in the range from -23.89 parts per thousand similar to-21.67 parts per thousand, and the average value is -22.67 parts per thousand. The water use efficiency of Picea meyeri increases in the range from 17.26 similar to 61.31, with an average of 39.45. (2) The delta C-13 of Picea meyeri is negatively correlated with temperature, which has the highest correlation with the temperature of the growing season (c5-c9), and its coefficient is higher than that of the mean temperature of each month. (3) There is a significant positive correlation between WUE sequence and temperature. Meanwhile, due to the effect of precipitation and temperature, the Picea meyeri is subject to drought stress to some extent. Above all, temperature is the main climatic factor affecting the delta C-13 and WUE of Picea meyeri on Luya mountain.