Study On Health Diagnosis Of Reserve Resources Of Platycladus Orientalis And Sabina Chinensis

Reserve resources of ancient trees refer to trees aged 50-100 years,which is an important part of ancient tree resources.Health diagnosis is an important part of health management of ancient trees and their reserve resources,including tree health evaluation and habitat quality evaluation.Through health diagnosis,the problems and hidden dangers existing in the health of ancient trees and their reserve resources can be found in time,which provides a scientific basis for targeted health management measures.In this paper,the reserve resources of Platycladus orientalis and Sabina chinensis were selected as the research objects,and the health and habitat quality of the reserve resources of P.orientalis and S.chinensis in Huangdiling,Ganling and North Campus of Northwest A & F University were investigated.The appropriate health evaluation factors were selected,and the health diagnosis technology system of the reserve resources of P.orientalis and S.chinensis was established.The relationship between the trunk water content and the accuracy of TRU tree radar tree trunk air decay detection was studied.The main results are as follows :(1)The principal component analysis method was used to screen out 8 indexes,such as leaf loss degree,branch loss degree,crown type,DBH,branch and leaf density,adjacent wood shading,trunk inclination degree and trunk damage degree.The weight of each index was determined,and the health evaluation index system of P.orientalis and S.chinensis reserve resources was established.K-means clustering method was used to determine the threshold of health status classification,and the health status of ancient tree reserve resources was divided into three grades,namely health,sub-health and unhealthy.(2)The health evaluation index system of Platycladus orientalis and Sabina chinensis reserve resources was applied to evaluate the health of 23 P.orientalis and 189 S.chinensis reserve resources in the north campus of Northwest A & F University,and 19 P.orientalis were found to be sub-healthy,1 healthy and 3 unhealthy;94 strains of S.chinensis in sub-health,92 healthy,3 unhealthy.(3)The tree stability and habitat quality(growth space,soil physical and chemical properties)of the reserve resources of Platycladus orientalis and Sabina chinensis in an unhealthy state were evaluated.The tree stability assessment was risky,mainly manifested as empty decay in the trunk and the empty decay rate was less than 30 %,which was mild empty decay.The evaluation results of habitat quality were poor and poor,respectively.The main manifestations were that the growth space of Platycladus orientalis and Sabina chinensis reserve resources was limited,the soil compaction was high,the aeration was poor,the N and P elements were relatively scarce,and the soil organic matter content was low.(4)Based on the results of health evaluation,stability evaluation and habitat evaluation,the factors leading to tree health damage were diagnosed,and the protection and restoration measures of unhealthy Platycladus orientalis and Sabina chinensis reserve resources were put forward,including soil improvement,tree support,dry rot prevention and pruning treatment.(5)The moisture content of standing tree trunk has an effect on the radar detection results,and the moisture content of tree trunk in different months is different.The moisture content of tree trunk in December is the lowest,and the moisture content of tree trunk in March is the highest.When the moisture content of tree trunk is lower,the empty decay results of tree trunk measured by TRU are more accurate.Therefore,in order to reduce the influence of seasonal variation of tree trunk moisture content on TRU detection accuracy,the highest detection accuracy is in December,which is the best time for detection.