考虑竞争因子的长白落叶松枝条大小混合效应模型OA

To explore the effects of diverse stand conditions on the branches of Larix olgensis,a total of 3 472 sets of branch ana-lytical data from 48 stem analysis trees of planted L.olgensis in Mengjiagang Forest Farm,Heilongjiang Province,were utilized.Stepwise regression was adopted to construct mixed-effects models for branch length(LB)and branch basal diam-eter(DB)of L.olgensis incorporating competition factors.Fixed-effect prediction plots of the optimal mixed models were generated to analyze the correlations between stand conditions and branch dimensions of individual trees.The results showed that the branch length mixed-effects model containing the Hegyi competition index(IC)and the sum of basal area of trees larger than the target tree per hectare(LBA)with tree sample identity as the random effect achieved the best fitting performance(R2=0.664,ERMS=0.421).Meanwhile,the basal diameter mixed-effects model incorporating height-diame-ter ratio(RHD)with tree sample identity as the random effect exhibited optimal fitting results(R2=0.560,ERMS=0.374).According to the fixed-effect prediction plots derived from mixed models,both branch length and basal diameter increased with rising relative crown depth into branch(CRDIN)and larger tree diameter at breast height(HDB).Additional-ly,trees with longer crown length(LC)possessed thicker branch basal diameters.Branch length was negatively correlated with Hegyi competition index and LBA,while branch basal diameter showed an inverse relationship with RHD.L.olgensis individuals with dominant status within stands exhibited superior branch growth potential.