Response of the relationship between radial growth and climatic factors to abrupt change of temperature along an altitudinal gradient on the northern slope of Changbai Mountain,Northeast China
The radial growth of trees is affected by complex environment. To predict the radial growth dynamics of Pinus koraiensis in the context of climate change,tree ring cores of P. koraiensis were collected from sampling sites at different elevations (745 m a. s. l.,1134 m a. s. l.,and 1280 m a. s. l.) on the northern slope of Changbai Mountain. Using a dendrochronological method,we investigated the variability in the responses of radial growth to climatic factors and the temporal stability of the responses at different elevations. The results from the Mann-Kendall test showed that an abrupt change in annual mean temperature occurred in 1987. Tree growth at the low elevation was mainly influenced by the precipitation that occurred in June and July,whereas tree growth at the middle and high elevations was mainly affected by the mean minimum temperature of July. After the abrupt change in temperature,the growth-climate relationship was relatively stable at the low elevation; however,the response of radial growth to precipitation during November of the previous year at the middle elevation and to precipitation that occurred in May at the high elevation changed significantly. Therefore,in the context of an abrupt change in temperature,the chronology of P. koraiensis at low elevations is more suitable for the study of regional climate reconstruction. However,when the temperature continued to rise,the radial growth of P. koraiensis showed a downward trend at the low elevation,whereas at the middle and high elevations,tree growth first increased and then decreased.