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    秦岭不同年龄太白红杉径向生长对气候因子的响应

    Age-dependent radial growth responses of Larix chinensis to climatic factors in Qinling Mountains, northwestern China

    • 摘要: 秦岭地区是我国最为典型的太白红杉温带针叶林分布区,也是受全球气候变化影响最为显著的地区之一。已有的研究已经显示树木的生理特征会随着树木年龄发生变化,这可能会造成与树木生长有关的气候信号随时间改变。为探索该区不同年龄太白红杉树木径向生长对气候变化的响应差异,本研究运用树木年轮气候学传统方法,研究了不同年龄太白红杉年表特征及其与气候因子的关系,以期揭示年龄因素对年表的潜在影响。结果表明:1)不同年龄太白红杉径向生长对气候因子的响应存在差异,老龄组太白红杉年表较中、低龄组年表对气候因子的响应更加敏感,更适合用于年轮气候学研究;2)响应函数分析表明,老龄组太白红杉年表对生长季早期和春季温度以及春季降水更加敏感,而幼龄组太白红杉年表与各月气候变量均未表现出显著相关关系。综上所述,太白红杉年轮宽度与气候变化的响应模式受年龄因素影响,高龄年轮年表对气候响应的敏感性更高,包含更多的气候信息。该研究结果为全球变暖背景下秦岭高山林线太白红杉林的合理经营管理及该区域气候重建提供了一定的基础数据。

       

      Abstract: Qinling Mountains, located in northwestern China, is the most typical distribution area of temperate coniferous forests, and is also one of the most significant areas affected by global climate change. Several studies have demonstrated that tree physiological characteristics undergoes changes with age. This may cause growth-related climate signals to vary over time. To explore this age-dependent effect, in this study, we tested the consistency of climate-growth responses in tree-ring series from L.chinensis trees of different age classes in relation near the alpine timberline in Qinling Mountains, a total of 240 tree-ring cores were sampled in the Aoshan, second peak of Qinling Mountains. In the concentrated distribution area of the upper limit, L. chinensis was grouped into three age classes: trees younger than 40 years (young age class, YAC), trees of 41-80 years of age (middle age class, MAC) and trees older than 81 years (old age class, OAC). Residual chronologies of the three age classes were built to analyze the climate-growth relationships using correlation and response functions. The results were as follows:1)differing among the three age classes, the chronology of old age class was more sensitive to climate change than the others, which was suitable for dendroclimatological analysis. 2)Response function analyses indicated that early growing season, early spring temperature and spring precipitation were the principal factors limiting its growth in the old age classes. However, there was no significant correlation between young age classes and all climate variables. Overall, the effects of age on the response of tree-ring width of L. chinensis to climate change, and the results of this study confirmed that the climate signal was maximized in older trees. Our study provides some basic data for the rational management of L.chinensis forest in relation near the alpine timberline in Qinling Mountains and the climate reconstruction in the region.

       

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