天水麦积山油松树轮宽度对气候变化的响应及其机制

The response and mechanism of Pinus tabulaeformis tree-ring width to climate change in Maijishan Mountain,Tianshui,China

为研究气候变化背景下天水麦积山风景名胜区1980—2019年油松径向生长与气候因子响应模式的变化及机制,利用树轮气候学方法和Vaganov-Shashkin模型,研究了气温突变前后天水麦积山油松的气候响应和生长过程。结果表明:(1)麦积山气温于1997年发生突变,突变后气温显著高于突变前。1980—1997年和1998—2019年油松与气候因子响应变化呈相关性下降(5月气温)、上升(10月气温、降水,7月降水,12月气温)和震荡(6月降水、7月气温)3种模式。(2)气候显著变暖使春秋季油松生长热量供应更加充足,生长季显著延长;夏季油松生长受到高温影响和水分胁迫。(3)油松生长与气候因子响应模式的变化主要是气候变暖和生长季的变化引起,如果气温持续上升其响应模式可能进一步变化,类似的变化过程可能也在其他油松生长区存在。

In recent decades,an unusual reduction in forest radial growth and temperature sensitivity has been widely observed in the northern high latitudes.Several studies have also suggested that unstable and nonlinear relationships exist between tree growth and its climatic drivers at mid-latitudes and even globally.However,this relationship remains poorly understood,particularly in the mid-latitudes.The climate response and growth process before and after the temperature abrupt change were investigated using dendroclimatological methods and the Vaganov-Shashkin model in order to research the variations and mechanisms of response of radial growth of Pinus tabulaeformis to climate factors in Maijishan Mountain,Tianshui,during 1980-2019.The findings revealed that:(1)According to the Mann-Kendall test,temperature changed abruptly in 1997 and then increased significantly.During 1980-1997 and 1998-2019,there were three patterns of response in radial growth to climate factors revealed in the variation in correlation with climatic factors:decline(Temperature in May),increase(Temperature and precipitation in October,precipitation in July and temperature in December),and fluctuation(Precipitation in June and temperature in July).(2)The Vaganov-Shashkin model estimated chronologies are significantly correlated with the measured tree-ring chronologies before and after the abrupt change(P<0.05).According to simulation results,significant climate warming resulted in more abundant heat supply for growth in spring and autumn,thereby significantly extending the growing season and potentially causing a change in response patterns in May and October.Furthermore,summer high temperatures and water scarcity impacted growth,potentially leading to a change in response patterns in July.(3)The change in response patterns to climate factors is primarily caused by climate warming and the lengthening of the growing season.If the climate continues to warm,the response patterns are expected to change,even more,and similar behavior may exist in other areas where the species is found.