Health Assessment Of Ancient Trees In Beijing

As live cultural relics, ancient trees are both special resources and an essential part of history and economy record, they play an important role in the study of history, meteorology, and ancient gardens. The research analyzed the tree form, chemical and physical characteristics of soil and chemical properties of leaves through investigating the ancient trees. This dissertation established the ancient trees health rapid and precision evaluation index system, and applied different evaluation methods to evaluate health condition of ancient trees. Sampling sites of the research include the Qing Wang Tomb, Ming Dynasty Yong Tomb, the Fragrant Hill, Ditan Park and the places near North Second Ring Road. The tree species including platycladus orientalis, pinus tabulaeformis, pinus bungeana and sophora japonica. This study evaluated the ancient trees health in Beijing comprehensively for the first time, The selected evaluation indicators have guiding significance to the ancient trees health evaluation, and they will provide advice and reference for conservation and rehabilitation of ancient trees.The main results were as follows:(1) Morphology study was conducted on365old trees. It analyzed the characteristics of different tree species, regions and age levels. From different regions, the average tree height, year increment of new branch, diameter at breast height of ancient trees in Ditan Park are bigger, and trunk inclination, leaves sparse situation, dry branches, tree holes are lesser, the general growth condition of ancient trees in Ditan Park are the best. From different tree species, Pinus bungeana Zucc.ex Endl. has the greatest tree height, the least dry branches, the smallest trunk inclination and no tree holes, the white pink ancient trees lives best relatively. The first-grade ancient trees perform better than the second-grade. Physiological characteristics of64ancient trees randomly selected have been analyzed. Elements in leaves of different trees are different. Soil physical properties of Platycladus orientalis is the best and the soil chemical properties of Sophora japonica is the best. Soil physical and chemical properties in Ditan Park are the best than other regions. The soil physical and chemical properties of most first-grade ancient trees show poor level than the second-grade ones.(2) The selection of ancient trees health evaluation indexes including morphology evaluation indicator and precision evaluation indexes. Rapid evaluation indexes including damage degree of tree trunk, degree of leaves dense, trunk inclination, deadwood proportion, increment of new branch, abnormal fallen leaves proportion and bare root ratio. Fifteen indices were chosen as comprehensive evaluation indicators, which are trunk inclination, year increment of new branches, dead branches ratio, soil capillary porosity, soil capillary porosity, soil water content and soil bulk density, soil pH, soil organic matter content, soil available N content, soil available N content of soil available P content, leaf Ca content, total K content and total K content in leaves.(3) The research used rapid evaluation method, the weighted principal component analysis, gray clustering analysis and BP neural network to evaluate ancient trees’health status. Rapid method evaluated365trees’ health status, the results shows that proportion of sub-health ancient trees is60.89%, proportion of healthy trees is33.80%, and unhealthy trees accounted for5.31%, there is no dying trees. Using weighted principal component analysis (pca) sorted the trees bases on their health status. According to gray clustering analysis, there are22healthy trees,33sub-healthy trees,6unhealthy tree and3dying trees of the64trees. Thanks to BP neural network for modeling analysis, it verifies the consistency of rapid evaluation method and precision evaluation method.