Study On Structural Characteristics And Adjustment Techniques Of Quercus Mongolica Secondary Forest In Daxing’ Anling

Taking Quercus mongolica secondary forest in Daxing’anling of Inner Mongolia as the research object,this thesis studied the diameter distribution characteristics of Q.mongolica secondary forest by setting fixed sample plots and using skewness coefficient and kurtosis coefficient.Four distribution functions,namely Weibull distribution,Gamma distribution,Logistic distribution and Normal distribution,were used to fit and test the diameter distribution law of Q.mongolica secondary forest,and the most suitable one to describe the diameter distribution of Q.mongolica secondary forest was selected.The age structure and dynamic changes of Q.mongolica population were analyzed by combining diameter class structure,static life table,survival curve and alive curve,and the spatial distribution pattern of Q.mongolica population was studied by point pattern method.In order to provide some scientific reference for the sustainable management and accurate improvement of forest quality of Q.mongolica secondary forest in Daxing’anling in the future,the structural adjustment scheme of Q.mongolica secondary forest was put forward.The main results are as follows:(1)The diameter structure of Q.mongolica secondary forest in Daxing’anling presented an irregular inverse “J” distribution,with an average diameter of 10.2cm and a diameter range of 5.0cm-35.7cm.The fitting effect of Gamma distribution function on the diameter distribution of Q.mongolica secondary forest was better,followed by Logistic distribution and Normal distribution,and the fitting effect of Weibull distribution was worse.(2)The age structure of Q.mongolica population showed an increasing trend,in which the number of individuals in age classes I and II(small trees)accounted for 46% of the total number of individuals in all age classes,the number of individuals in age classes III and IV(medium trees)accounted for 32% of the total number of individuals,and the number of individuals in age classes V,VI and VII(large trees)accounted for 22% of the total number of individuals.The results showed that the young individuals of Q.mongolica secondary forest were sufficient,while the big trees were relatively small.The number of new individuals would decrease with the increase of age,and the intraspecific competition would continue to increase.(3)The survival curve of Q.mongolica population was close to Deevey II(straight line),and the change curves of mortality and disappearance rate were basically the same.With the succession of the community,the individual of Q.mongolica tended to mature gradually,which led to the intensification of intraspecific competition and the increase of population mortality.Time series analysis showed that the population of Q.mongolica will show a stable growth trend in the next 2,4 and 6 years.(4)The number density of Q.mongolica in the sample plot is small > medium > large.The population of Q.mongolica shows aggregation distribution as a whole,which is mainly affected by small-diameter and medium-diameter trees.Small trees and middle trees,small trees and big trees,middle trees and big trees are not related,which shows that different age classes of Q.mongolica are independent of each other,which is conducive to the stable growth of Q.mongolica population.(5)According to the current situation of Q.mongolica secondary forest,three methods of artificial promotion of natural regeneration,forest tending and artificial replanting were put forward to optimize and adjust the structure of Q.mongolica secondary forest.The purpose is to construct the existing stand into a "multi-layer,different age,mixed" stand,so as to improve the stand structure,increase the stand quality and promote the succession of Q.mongolica secondary forest.