呼伦贝尔沙地不同树龄樟子松对气候的响应

【目的】对呼伦贝尔沙地不同树龄樟子松年表的特点及其径向生长与气候因子的关系进行探讨,分析不同树龄樟子松对气候响应的差异性,为该地区沙地樟子松的年轮气候学和不同树龄组沙地樟子松的经营管理提供一定的理论依据。【方法】采用COFECHA、ARSTAN程序建立标准年表,利用呼伦贝尔沙地两个样地的樟子松(Pinus sylvestris var. mongolica)样芯,划分成3个不同树龄组,运用DendroClim2002进行标准年表与气候因子响应分析。【结果】从不同树龄组的年表统计特征值发现,平均敏感度(MS)相差不大,都含有较高的气候信号。不同树龄组的一阶自相关(AC₁)是逐渐递增的,不同树龄组的信噪比(SNR)和样本代表性(EPS)都以中龄组最高,老龄组最低。从响应分析的结果来看,低龄组对气温的敏感性最高,老龄组对降水的敏感性最强。中龄组受前一年6月、7月的降水和最低气温共同影响显著,与6月的平均气温也呈显著负响应,同时与前一年12月的降水呈显著负响应。【结论】呼伦贝尔沙地不同树龄组樟子松的径向生长受气候条件的响应不尽相同,老龄组树木的生长对前一年12月的降水最为敏感,达到响应系数的最高值,低龄组和中龄组的生长都出现了与6月气温之间的负响应关系,这些是否与全球变暖、大兴安岭地区气候暖干化趋势加强有关,还需要进一步的研究。

Age-dependent-tree-ring growth responses of Pinus sylvestris var.mongolica to climate in Hulunbuir sandy land

【Objective】Because Scotch pine(Pinus sylvestris)plays an important ecological role in windbreak,sand fixation and farmland protection and so on in the north of China,we discussed the characteristics of the chronology of its tree rings in different age-classes and the relationship between its radial growth and climate factors and analyzed the differences in its responses to climate,to provide a theoretical basis for the dendroclimatology and forest management of Pinus sylvestris var.mongolica under different age-classes.【Method】The COFECHA and ARSTAN programs were used to establish a standard chronology.Pinus sylvestris var.mongolica of 67 sample cores were obtained from two plots in Hulunbuir sandy land,China,and divided into three age-classes:young age trees-less than 55 years,13 cores;middle age trees-more than 55 years and less than 100 years(A55-100),36 cores;old age trees-more than 100 years(A100),18 cores.The standard chronology and climate factor responses were obtained using DendroClim 2002 analysis.【Result】Based on the statistical characteristic values of tree-ring-width chronologies under different age-classes,the results indicated that the mean sensitivity of the three age-classes was similar,responding to higher climate signals.The first-order autocorrelation(AC1)gradually increased in the different age-classes.Signal-to-noise ratio(SNR)and expressed population signal(EPS)were the highest in middle-aged trees,whereas the lowest values were found in old-aged trees.Our results showed that the sensitivity of radial growth in young-aged trees to temperature was the highest,whereas the old-aged trees were the most sensitive to precipitation.The middle-aged trees were more affected by the precipitation and minimum temperature in June and July of the preceding year;however,radial growth of the middle-aged trees in the area was significantly negatively correlated with the mean temperature in June and the precipitation in December.【Conclusion】The radial growth of Pinus sylvestris var.mongolica in different age-classes in Hulunbuir sandy land was affected by the climatic response.The growth of trees in old age was most sensitive to the precipitation in December of the previous year,reaching the highest value of response coefficient.The growth of both the young-and middle-aged trees exhibited a negative response to the temperatures in June.Thus,further research is needed to determine whether the climatic factors are related to global warming and the resulting warm and dry climate in Daxing’an Mountins,China.