| In order to reveal the relationship between the branch properties of the Pinus koraiensis plantation and thinning treatmemt,this study was conducted based on 4370 sets of branch analysis data obtained from 49 trees from plots with different thinning intensities(unthinned,10～20%,20%～30%,30～40%)in Linkou Forestry Bureau and the Dongjingcheng Forestry Bureau in Heilongjiang Province,and the influence of thinning on the branch properties was analyzed.Using R,the stand thinning factors(thinning intensity,TI,thinninng age,TA)are quantified,and the method of linear and non-linear mixed effects models are used to develope the models of the branch density,the maximum branch diameter and branch length of Pinus koraiensis plantation,and the adjusted coefficient of determination(Ra2),Akaike information criterion(AIC),Bayesian information criterion(BIC),log likelihood value(Log likelilood)and likelihood ratio test(LRT)are used to evaluate the models,and the fixed effect composition of the models are used to dynamically simulate the vertical distribution along the relative depth into crown(RDINC)of the branch properties of the Pinus koraiensis plantation with different thinning intensities and sizes.The results indicates:(1)The results of the non-linear mixed model of branch density based on thinning effects showed that the best fitting occurs when the plot effect acts on the natural logarithm of the relative depth into crown(lnRDINC),and the square of relative depth into crown(RDINC2),diameter at breast height(DBH)and the thinning intensity over thinning age(TI/TA),whose Ra2 was 0.7885,RMSE was 2.3952.The dynamic simulation of the vertical distribution of branch density through the optimal model showed that the branch density of Pinus koraiensis reaches the peak at about 35%from the top.The rate of survived branches in the lower canopy as well as the branch density increased with thinning intensity.But the branch density among different thinning age and tree size varies insignificantly.(2)The results of the linear mixed model of the maximum branch diameter based on thinning effects showed that the growth of the maximum branch diameter of the thinning plots was generally greater than that of the control plot,and the growth rate of the branch diameter of Linkou Forestry Bureau was significantly greater than that of Dongjingcheng Forestry Bureau.The best fitting occurs when the plot effect acts on the intercept,lnRDINC,RDINC2,and the height-to-diameter ratio(HDR),and the random effect variance-covariance structure was unstructured(UN),the error autocorrelation structure was the first-order autoregressive and moving average structure(ARMA(1,1)),whose Ra2 was 0.9243,RMSE was 0.1208.The dynamic simulation of the vertical distribution of the maximum branch diameter through the optimal model showed that the maximum branch diameter of Pinus koraiensis reaches the peak at about 55%from the top.The growth of the branch diameter increased with thinning intensity,while varying significantly among different thinning intensities,and reached the maximum when thinning intensity was high.(3)The results of the linear mixed model of the branch length based on thinning effects showed that cumulative growth of branch length showed significant increase with increasing branch age,and the cumulative growth of branch length in each thinned plot was significantly greater than that in the controlled ones generally,and the branch growth rate of Linkou Forestry Bureau is significantly greater than that of Dongjingcheng Forestry Bureau.The best fitting occurs when the plot effect acts on the RDINC2,lnRDINC,DBH and TI,whose Ra2 was 0.9606,RMSE was 0.1380.The dynamic simulation of the vertical distribution of the branch length through the optimal model showed that the branch length of Pinus koraiensis reaches the maximum at about 75%from the top.The growth of the branch length increased with thinning intensity,while varying significantly among different thinning intensities,and reached the maximum when thinning intensity was high. |
