秦岭中西部油松径向生长对气候因子的响应差异研究

Different responses of radial growth of Pinus tabuliformis to climate in the middle and western Qinling Mountains

在气候变暖背景下,树木径向生长对气候因子的响应会随区域干湿变化而有所差异。秦岭属于气候敏感区和生态脆弱区,南北气候特征差异明显,分析气候变化背景下树木径向生长对气候因子及干旱事件的响应,对准确预测未来气候变化对树木生长的影响至关重要。为探究该地区不同干湿环境下油松对气候因子及干旱事件响应的特点及差异,共采集秦岭中西部南北坡共4个样点的油松树轮样芯,利用树木年轮生态学的方法,分析各地油松年表与气候因子之间的关系,通过计算抵抗力、恢复力、恢复弹力等指标探究树木径向生长对干旱事件的应对能力,结果表明:1)在西部和北坡的3个样点,油松径向生长主要与前一年7—9月、当年5—7月的气温呈显著负相关,与当年5月降水呈显著正相关,在中部南坡油松径向生长主要与当年2—4月、9月气温呈显著正相关,与当年4月降水呈显著负相关;2)生长季气温升高所引发的水分亏缺,是研究区西部和北坡油松径向生长受限制的主要原因,且中部南坡油松生长受气温和干旱因子的制约要明显弱于其它3个样点;3)西部北坡油松对干旱的抵抗能力、恢复能力及恢复弹力均弱于西部南坡及中部北坡油松。在未来对研究区树木的管理与保护工作中,应更加关注西部北坡树木生长状况,中部树木则无需进行过多的人工干预。

In the context of global warming, the responses of tree radial growth to climate factors usually vary with the regional dryness and wetness. Qinling Mountains is located in a climate-sensitive and ecologically fragile region, whose north slope and south slope show different climatic characteristics. It is essential for accurately predicting the impact of climate change on tree growth by analyzing the response of trees radial growth to climate factors and drought events in the context of climate warming. In order to explore the response of the radial growth of Pinus tabuliformis in the Qinling Mountains to climatic factors and drought events in different moisture conditions, we collected tree-ring cores at four sampling sites on the south and north slopes of middle and western Qinling Mountains. We analyzed the relationships between the chronology of Pinus tabuliformis and climate factors at different sites by using the method of dendroecology. Indices, e.g. resistance, recovery, and resilience, were defined and used to explore the coping capacity of radial growth to drought events. Our results indicated that: 1) in western and north slope Qinling Mountains, the radial growth of Pinus tabuliformis was negatively correlated with mean temperature from July to September in the previous year and that from May to July in the current year, and was also positively correlated with monthly total precipitation in May. On the south slope of middle Qinling Mountains, Pinus tabuliformis was positively correlated with mean temperature from February to April, monthly mean temperature and mean minimum temperature in September in the current year. Pinus tabuliformis was also negatively correlated with monthly total precipitation in April. 2) The main factor restricting the radial growth of Pinus tabuliformis in the western and north slopes of the study area was the water deficit caused by the increased temperature in the growing season. The limiting effects of temperature and drought on the radial growth of Pinus tabuliformis in the south slope of middle Qinling Mountains were significantly weaker than those at the other three sampling sites. 3) Pinus tabuliformis in the north slope of Qinling Mountains showed lower resistance, recovery and resilience to drought events than trees on the south slope of western Qinling Mountains and on the north slope of middle Qinling Mountains. In the future management and protection for the trees in the study area, more attention should be paid to the growth of the trees on the north slope of the western Qinling, and the trees in the middle Qinling do not require excessive manual intervention.