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

Abstract

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.