长白山北坡不同海拔红松径向生长-气候因子关系对气温突变的响应

树木径向生长受复杂环境的影响。为预测气候变化背景下未来红松(Pinus koraiensis)径向生长动态变化,在长白山北坡采集3个海拔梯度(745、1134、1280 m)红松树轮样芯,运用树木年轮学研究方法,分析不同海拔红松径向生长-气候因子关系对气温突变的响应差异。结果表明:(1)通过对采样点附近气象站气温数据的M-K检验发现,年均温在1987年发生显著突变;(2)低海拔红松径向生长主要受当年生长季6—7月降水的影响,中、高海拔红松径向生长主要受当年7月平均最低气温的影响;(3)气温突变以后,低海拔红松径向生长-气候因子关系较为稳定,中海拔红松径向生长对前一年11月降水量的响应关系发生显著改变,高海拔红松径向生长对当年5月降水量的响应关系发生显著改变。因此,气温突变背景下,低海拔红松树轮年表更适用于区域气候重建等研究。同时随着气温持续升高,低海拔红松径向生长可能呈现下降趋势,中、高海拔红松径向生长可能呈现先增加后下降的趋势。

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.