Study On The Stand Structure And The Model Of The Timber-produced Rate Of Timber Assortments Of The Large Diameter Timber Plantation Of Pinus Massoniana In Eastern Sichuan

Pinus massoniana is one of the fundamental timber species in southern China.Although the cultivation of Pinus massoniana doesn’t need very high quality soil and environment,its growth cycle is very long,especially the large diameter Pinus massoniana,which will be cultivated for a longer period of time.Knowing the stand structure of the large diameter Pinus massoniana and building the model of the timber-produced rate of timber assortments of the large diameter Pinus massoniana plantations can provide a theoretical basis for operators to develop correct forest management measures in order to increase the yield of target timber assortment,obtain higher economic benefits,protect forest resources effectively,maximize the protection and use of resources and gain higher ecological benefits at the same time.With different site conditions,different ages,different densities and different management intensity,the representative standards were set up in the Pinus massoniana plantation in eastern Sichuan,which were selected as many as possible followed the typical sampling method.There are 50 representative standards and each covers an area of 20m×20m.The data of 1627 wood with each wood gauging,220 wood and 24 analysis trees was collected.The data of 1627 wood with each wood gauging was used to build and test the required basic model.The data of 220 wood and 24 analysis trees was used to construct and test the binary volume model and the binary ground diameter tree volume model.The data of 220 wood was used to fit and test the taper equation,and the basic model was used to compile the material yield rate table and the construction and test of each material yield rate model.The results are as follows:（1）The diameter distribution and tree height distribution of Pinus massoniana plantation tested by Chi-square obeyed the Weibull distribution in the eastern Sichuan region.（2）According to the data law,a variety of models were selected for fitting.the coefficient of determination（R²）and the sum of squared residuals（RSS）were used to select the optimal DBH height model=1.571_1.3^0.750（84）,DBH ground diameter model（85）,ground diameter tree height model（86）,under（over）bark diameter model（87）,binary volume model（88）and binary ground diameter tree volume model（89）on the basis of（88）model and（89）model.The purpose was to compile a suitable binary volume table and binary ground diameter tree volume table for the Pinus massoniana plantation in the eastern Sichuan region.（3）The nonlinear regression analysis of the wood data was carried out by SPSS 20.0software.Iterative method was used to fit the four taper equations.After comparing the residual sum of squares（RSS）,residual mean square error（MRS）,residual Standard deviation（S）and determination coefficient（R²）,the measured values of the test sample and the estimated values obtained by the equation were used to calculate the average relative error（E）,the average relative error absolute value（RMA）and the pre-measure of each of the taper equations.The accuracy（P）was evaluated for practicability,and the optimal taper equation（90）of Pinus massoniana in eastern Sichuan was selected eventually.（4）The table showing the timber-produced rate of various timber assortments of Pinus massoniana in the eastern Sichuan region was compiled,and the model of the timber-produced rate of various timber assortments was fitted.The test sample measured value,the timber-produced rate table and the estimated value of the timber-produced rate equation were used to calculate the average relative error（E）,the average relative error absolute value（RMA）,and the estimated accuracy（P）to perform accuracy test.The result shows that the compiled timber-produced rate table of timber assortments of Pinus massoniana can be applied to the eastern region of Sichuan.The optimal models（91）to（94）of two-dimensional timber-produced rate of various timber assortments were selected,and the optimal models（95）to（98）of one-dimensional timber-produced rate of various timber assortments were selected.（5）The table showing the timber-produced rate of ground diameter timber assortments of Pinus massoniana in the eastern Sichuan region was compiled,and the model of the timber-produced rate of the various timber assortments ground diameter was fitted.The test sample measured value and the timber-produced rate table and the timber-produced rate equation estimated value were used to calculate the average relative error（E）,the average relative error absolute value（RMA）,and the estimated accuracy（P）to perform accuracy test.The result shows that the compiled timber-produced rate table of ground diameter timber assortment of Pinus massoniana can be applied to the eastern Sichuan region.The optimal models（99）to（102）of two-dimensional ground diameter timber-produced rate of various timber assortments were selected,and the optimal models（103）to（106）of one-dimensional ground diameter timber-produced rate of various timber assortments were selected.In dealing with deforestation,illegal logging,and forest rights disputes in forestry production practices,it is often necessary to estimate the economic value of the logging.Then,the ground diameter volume table plays an important role.However,the ground diameter volume table can only be used to estimate the volume of the felled wood,and it is impossible to know the amount of material produced.The yield of each material is different,and its economic value is also different.Therefore,based on the estimation of the felled wood product,constructing the model of the ground diameter timber-produced rate can estimate the output of each timber assortment further and estimate its economic value more accurately,which has a great practical significance in the practice of forestry production.On the other hand,understanding the stand structure of the large diameter timber of Pinus massoniana and establishing the model of the timber-produced rate of timber assortments of the large diameter timber plantations of Pinus massoniana can predict the yield of large diameter timber of Pinus massoniana,which plays an important role in developing correct forest management measures for operators.