天山北坡中东部高海拔树轮宽度年表的建立

Development of the Tree-ring Width Chronologies in the High-elevation Regions in the Middle and East Tianshan Mountains

通过对天山北坡中东部高海拔的几个树木年轮采样点样本的研究,建立了天山北坡中东部高海拔树木的一系列树木年轮宽度的可靠年表,其中最长差值年表为321年。差值年表间的相关分析和主成分分析显示,不同树种之间树木生长存在很大的差异。不同树种的标准年表(STD)的均方差都比差值年表(RES)的大,而平均敏感度都较差值年表(RES)的小,说明差值年表(RES)保留的高频振荡信息要比标准年表(STD)多;偏度系数几乎都偏向大于均值的一方,而天山云杉的差值年表峰度系数变化更趋平缓;六个采样点共同区间上的各项指标几乎都是差值年表(RES)值高于标准年表(STD)值,说明天山北坡中东部高海拔的不同树种中差值年表(RES)均含有较高的环境信息。这些树木年轮宽度年表特征将为今后本地区的树木年轮生态学研究奠定基础。

In this paper, the tree-ring cores collected from six sites in three high-elevation regions （i.e., Miquan, Mori and Barkol） in the middle and east Tianshan Mountains, an arid and semi-arid region in northwest China, during the period from September to October 2002, are used to develop six tree-ring width chronologies using standard dendrochronological methods. The tree-ring cores were collected from the trees of Picea schrenkiana Fiseh growing at four high-elevation sites in Miquan and Mori and of Larix sibiriea Ledb growing at two high-elevation sites in Barkol. More than twenty trees were drawn at breast height, and two cores were drawn from each tree in different directions. The sampling cores were mounted in wooden strips, sanded to 600 grits until resolving late-wood boundaries. At last the measured rings were checked using Cofacha software and line plots. The results show that all the average correlation coefficients （R） between sample series and master series at six sampling sites exceed 0.6. Picea schrenkiana Fisch from Mori A and B are regarded as the superior conditions from mean ring-width （R.W.）, mean sensitivity （M.S.） and lose-ring ratios of these results. The measured and crossdated ring-width series from each tree is standardized. A chronology is developed for each site. In order to develop the reliable chronologies, we take samples of subsample signal strength above 0.8 （i.e. sss≥0.8） as the beginning for developing the chronologies. Thus, these chronologies are extended to the year of 2002, and the longest chronology has 321 years in all dependable chronologies. The results of correlation and principal component （PC） analysis in all dependable chronologies show that the tree growth among tree species makes a great deal of difference. The statistical results of the chronologies in different tree species show that the standard deviations of the standardized chronologies are higher than those of the residual chronologies, but the mean sensitivity of the residual chronologies is high. Most of the statistics in the common interval analysis at six sampling sites are higher in the residual chronologies than that in the standard chronologies, which reveal that the residual chronologies of some sampling sites of different tree species at high-elevation regions in the middle and east Tianshan Mountains contain more environmental information than the corresponding standard chronologies. These conclusions are important for the tree-ring research in arid and semi-arid areas.