柴达木盆地东缘祁连圆柏轮宽序列标准化的方法研究

利用在青海柴达木盆地东缘山地获取的大量祁连圆柏树轮资料,对拟合并去除树木生长趋势即标准化方法进行探讨,提出了一种总体曲线方法.该方法用包含完整树木髓心、并且在40～60年间达到生长顶峰的树轮资料拟合柴达木盆地东缘祁连圆柏的总体生长趋势曲线,并用广义的负指数函数来描述树木自茎的次生生长开始以来的径向生长过程.用相同的树轮资料建立估算缺失轮数的最初径向生长模型,其方差解释量高达90.9%.建立年表时包含髓心的样芯认定生理年龄为1年,不包含髓心的样芯用最初径向生长模型估算缺失轮数,然后全部样芯用生长趋势曲线对应部分进行去趋势标准化.该方法对建立可靠、准确的长年表有重要意义,所建年表比用传统负指数函数方法建立的年表保留了更多的低频变化信息.

Standardization of Qilian Juniper Ring-width Series in the Eastern Margin of the Qaidam Basin

Standardization of tree-ring data is one of the most important procedures in dendroclimatology.We used abundant Qilian juniper(Sabina przewalskii Kom) tree-ring samples along the eastern margin of the Qaidam Basin to approximate the growth trend to generate a total growth trend curve.We used samples that contained complete pith reaching to a growth culmination in 40-60 years to estimate the total growth trend curve,and then employed the generalized negative exponential function to fit the curve.Usually,most sample cores cannot reach the tree pith for various reasons and it is difficult to determine the trees' cambial ages.An empirical model of initial radial growth(IRG) was developed to estimate the number of rings missing from the pith based on the same tree-ring data and the IRG model explained 90.9% of the variance.When constructing the chronology,the cambial age of the first ring from the pith is regarded as 1 year.Then the ages of the rings in samples without piths were determined by the estimated numbers of missing rings in the cores.Standardization was accomplished by dividing each tree-ring series by the corresponding values of the total growth trend curve.The chronologies developed by this method can preserve more low-frequency variability.This method helps to construct more reliable tree-ring width chronologies.