| Taking Pinus koraiensis plantation of Linkou Forestry Bureau in Northeast China as the research object,the plots were divided into four grades according to different thinning intensities(heavy thinning:plant number intensity 65%,accumulation intensity 43%,medium thinning:plant number intensity 50%,accumulation intensity 28%,and light thinning:plant number intensity 40%,accumulation intensity 18%).Three evaluation factors for growth situation,stem shape and branching conditions,including height mean increment,DBH mean annual increment,crown diameter ratio,ratio of height to diameter,tree tapering,Bifurcation ratio,loose knot ratio,natural ability of self-thinning,lateral branch number(>1.5cm),Index of branch diameter,average base diameter of branches were used as the evaluation indicators for Pinus koraiensis form quality.Analytic Hierarchy Process(AHP)was used as the main analysis method to establish the hierarchy structure model and evaluation index system of Pinus koraiensis plantations,and comprehensively evaluate the form quality of the Pinus koraiensis plantations under different thinning intensities.The highest comprehensive form quality score of 73.427 was obtained for medium thinning,which showed the best form quality that the quality evalution grade is Ⅱ,68.114 for heavy thinning with grade Ⅲ,59.150 for light logging with grade Ⅳ,and 43.432 for the control group with grade V.The control group had an comprehensive form quality score of 43.432 with gradeV.The habitat of reserved trees in canopy closure Pinus koraiensis plantations can be improved by proper thinning,among which,the form quality of trees reflected by medium thinning is the best,followed by heavy thinning and the least by light thinning.The tree stem condition has the greatest influence on the Pinus koraiensis form quality.The character index of judgment matrix can be concluded that accounts for about 65.5%of the proportion,which can provide a theoretical basis for the evaluation of the tree form quality of Pinus koraiensis plantations and other coniferous and broad-leaved species in Northeast China,as well as local production and thinning of Pinus koraiensis plantation. |
