基于树木年轮学的古树树龄估算——以敦煌市香水梨为例

树龄是古树鉴定的唯一标准。本研究采用树轮年代学方法调查敦煌市莫高镇窦家墩村四组(原杨家园子)梨园中最老的香水梨树的树龄。因老梨树均腐朽中空,调查同时采集不同树龄的香水梨树样芯,建立树木径向生长生理年龄曲线,据此估算缺失段的树轮数。结合准确树轮计数,复原香水梨树树龄。结果表明: 梨园13棵老香水梨树的平均树龄为(280±35)年。由此证明,《敦煌志》中记载的古梨树是真实存在的。按树龄来说,该批梨树至少为三级古树,应妥善保护。本研究为解决敦煌市古梨园存留争议提供了详实的科学依据。

Age estimation of ancient trees based on dendrochronology: A case study of Pyrus ussuriensis in Dunhuang City,China

Age is the sole criterion for identifying ancient trees. Dendrochronology was used to examine the age of the old trees of Pyrus ussuriensis in the Fourth group of Doujiadun Village (formerly Yangjiayuanzi), Mogao Town, Dunhuang City. As all the old pear trees had been decayed and hollow, we collected cores of P. ussuriensis of different ages to establish the age-related curve of tree radial growth, and estimated the number of tree rings in the missing segment. Combined with accurate count on tree rings, the age of P. ussuriensis was restored. The results showed that the average age of the 13 old pear trees in the orchard was (280±35) years, presenting further evidence for the record about old pear trees in Dunhuang Zhi. These old trees could be classified as the third-class ancient tree according to tree age, and should be properly protected and preserved. This study provided a detailed scientific basis to resolve the dispute over the conservation of ancient P. ussuriensis in Dunhuang City.