Construction Of The Additivity Model System Of Heartwood,Sapwood And Bark For Pinus Koraiensis Plantation

In this paper,103 artificial Pinus koraiensis plantation trees were selected under different forest conditions in each region and processed by Windendro 2003 annual rings image analysis system to obtain 2977 discs data from Mengjiagang Forest Farm,Dongjingcheng and Linkou Forestry Bureau in Heilongjiang Province of northeastern China.Analyze the growth and development laws of heartwood,sapwood,and bark.Combine 10 typical taper models and create taper models for diameter outside bark（DOB）,heartwood diameter（HD）,sapwood width（SW）,and bark thickness（BT）,then compare and select the best base model.On the above basis,we use the seemingly unrelated regression（SUR）method in the PROC MODEL of SAS software to establish an additive model system for the taper equations of DOB,HD,SW,and BT.The system included dummy variables for the region,and a comprehensive evaluation of the model.The models were then evaluated by coefficient determination(R²_adj),root mean square error（RMSE）,Akaike information criterion（AIC）and Bayesian information criterion（BIC）.Finally,the heartwood,sapwood,and bark volume were predicted by numerical integration.The results of this study showed:（1）The analysis of the growth patterns of heartwood,sapwood,and bark showed that the growth of heartwood,sapwood,and bark was mainly related to tree diameter at breast height（DBH）and tree height,followed by height to diameter ratio,crown width,crown length,and tree age,which also had some influence on the growth of heartwood,sapwood,and bark.DOB,HD,SW,and BT all tended to decrease with increasing tree height,while DOB and HD followed the same trend,and SW and BT changed more steadily.The cambium age influenced the age of the heartwood and sapwood,and the linear regression equation revealed a heartwood formation rate of 0.61-0.71 for different areas and grades of wood,as well as a heartwood initiation age of 2.3-3.9 years.Pinus koraiensis plantation heartwood gradually disappears at a relative height of about 0.8.The maximum height of heartwood（HHD）has a strong linear correlation with tree height,and the DBH and tree age also have some influence on the HHD,based on this result,a linear regression model containing only tree height as the HHD model.（2）The results of the additivity model system based on different regions showed that the taper model developed by Kozak（2004）can be used as the optimal basic model for the DOB,HD,SW,and BT.The additivity model system is built using the individual fitting method,the total amount control method,and the three deformations of the total amount control method,all based on the optimal taper model.The five additivity model systems got better prediction effects,and the prediction precision was more than 98%.After a thorough analysis,the total amount control approach was chosen as the best additivity model system.And in the optimal additivity model system,incorporate regions as dummy variables into the model.The additive model system with dummy variables improved the prediction ability in varying degrees,especially the prediction precision of HD model and SW model.（3）The predicted results for heartwood,sapwood,and bark wood volume indicate that the volume measured by the model’s numerical integration and the volume measured by the segmented summation has a strong correlation.Diameter outside bark volume（DOB＿V）,heartwood volume（HD＿V）,sapwood volume（SW＿V）,and bark volume（BT＿V）all had R²values of 0.97,0.95,0.94,and 0.86,respectively.Numerical integration can be used to measure the volume of heartwood,sapwood,and bark wood for better results.The additivity model system with dummy variables not only has high prediction accuracy but also satisfies the additivity logic DOB,HD,SW and BT,which provides a basis for accurate estimation of heartwood,sapwood and bark volume of P.koraiensis.