玛纳斯河流域不同海拔树轮宽度年表特征及其对气候响应的对比分析

Characteristics of Tree-ring Width Chronologies and Their Response to Climate for Different Elevations in Manasi River Basin

利用位于玛纳斯河流域地区不同海拔高度的6个采样点的树木年轮宽度资料,建立其宽度年表,并分别将位于上树线区域的2个年表和下树线区域的3个年表合成,得到森林上树线年表(MNU)和下树线年表(MNL),将涝坝湾年表作为森林中部年表(MNM)。对比3个树轮宽度标准化年表的特征参数及年表对气候的响应,结果表明:(1)样本总体代表性、平均敏感度、信噪比、第一特征向量百分比随着海拔的升高而递减。(2)高频信息量随着海拔的升高而递减,而低频信息量随着海拔的升高而递增。(3)气温是制约森林上树线年表(MNU)的主要气候限制因子;而对于森林下树线年表(MNL)与森林中部年表(MNM)来说,降水起直接的正向影响作用,气温则发挥间接的反作用,均具有明确的树木生理学意义[1]。

Tree-ring cores taken from six sites at different elevations in Manasi River Basin were used to develop six tree-ring width chronologies. Combining the two chronologies of which located near the upper limit of the forest to create the MNU chronology and combining the three chronologies of which located near the lower limit of the forest to create the MNL chronology, while the LBW chronology was regarded as the MNM chronology. By comparing the parameters of the three standardization chronologies and their response to climate change ,the results indicated that：（1）express population signal （EPS）、mean sensitivity （MS）、signal-to-noise ratio （SNR） and Autocorrelation order 1 （AC1） decreased within increasing elevation.（2） The amount of high frequency information decreased and within increasing elevation and that of the low frequency information increased within increasing elevation.（3）Temperature was the main climatic limiting factor for the MNU chronology. For the MNL chronology and MNM chronology, the precipitation played a positive role and the temperature exerted indirect retroaction, and their correlation had obvious physiological significance.