The Change Rule And Prediction Model Of Heartwood Of Larch

Based on the data of 1179 discs and whorls of 49 trees from Korean larch(Larix olgensis)plantations in 7 plots from Mengjiagang forest farm in Jiamusi city of Heilongjiang Province.We analysed the change rule of the heartwood radius,heartwood area and heartwood area percentage of the Larix olgensis plantations.Then,a linear mixed effect model for the heartwood radius and heartwood area of Korean larch was established.And based on the beta distribution,a generalized linear mixed effect model for heartwood area percentage was constructed.Using SAS 9.3 software,the evaluation statistics such as AIC,BIC,Log Likelihood and Likelihood ratio test were used to compare different models.The results are as follows:1.The heartwood radius and heartwood area showed a gradual decrease as the tree height became larger in the longitudinal direction.The heartwood radius and heartwood area were larger in the base of the trunk.And the change of them was closely related to the change of the trunk.The variation trend of the heartwood radius was especially similar to the change of the trunk.Sapwood transformed to heartwood at a relatively stable rate when the tree reached a certain age or diameter.With the increasing of DBH,the heartwood radius and heartwood area gradually increased,and the relationship between them and DBH showed a positive correlation.With the increasing of the depth into tree of the disks,the heartwood radius and heartwood area gradually increased.With the increasing of tree height,the heartwood area percentage showed a decreasing trend.And it gradually increased with the increasing of DBH,xylem radius and cambial age.The interpolation method was used to calculate the height of heartwood,and the ratio of heartwood height to tree height could be calculated according to it.The length between the position heartwood disappeared and the tip of the tree varied from 0.92m to 4.32m.The height of heartwood could reach 49%-94%of tree height.And this proportion increased with the increasing of the tree height,DBH,tree age and crown width.2.We used stepwise regression analysis to establish the model of heartwood radius and heartwood area of Korean larch:HR=b1+b2DIT+b3DIT2+b4DBH,HA = b1 + b2DIT + b3DIT2 +b4DBH-DIT.Using the evaluation statistics,we compared the model of heartwood radius and heartwood area with plot effect and tree effect.The model comparison showed the prediction accuracy of the mixed model was better than the basic model.So in the application,the total heartwood radius and area can be predicted by the mixed model.3.In this study,we established a generalized linear mixed effect model for heartwood area percentage based on the beta distribution.In the best model selected,all parameters were significant.And the model had good simulation effect.The heartwood area percentage of larch plantation in this area can be estimated by this model.On the whole,the linear mixed effect model and generalized linear mixed effect model constructed by this research would be suitable for predicting the heartwood radius,heartwood area and heartwood area percentage for the study area.And it could provide theoretical basis for the future production and management and heartwood research of Korean larch plantations.This model is only applicable to the area studied in this article.But with the accumulation of data,it will be possible for us to further carry out the model related to heartwood in macro region.