利用削度方程编制巨尾桉材种出材率表的研究

Compiling the Ratios and Assortments of Merchantable Timber Volumes of Eucalyptus grandis×E.urophylla Using Taper Equations

以云南省临沧市双江县138株巨尾桉人工林造材样木为研究材料,分编表样本103株,检验样本35株,选择国内外常用的8个削度方程作为备选方程,根据编表样本的造材数据,应用SPSS软件进行非线性回归分析拟合削度方程参数,根据国内现行材种出材率表编制技术规程的相关要求,以离差平方和、相关指数和一定高度树干直径实测值与削度方程估计理论值之间的偏差、绝对偏差、相对均方差和平均相对偏差作为评价指标进行对比分析,结果表明:备选的8个削度方程中d/D=[(H-h)/(H-1.3)]^(f(D,H,h))拟合精度最高,相关指数(R^(2))为0.97957,适用于作为编制巨尾桉材种出材率表的最佳削度方程。在确定编表削度方程的基础上,建立树干去皮与带皮直径回归方程和树皮率回归方程,进行理论造材、以编表样本数据编制材种出材率表,根据材种出材率表编制技术规程的技术要求,分别进行编表精度检验和使用精度检验。编表精度检验的结果表明,巨尾桉一元出材率表主要材种胶合板原木平均系统误差为-0.06%,造纸原木平均系统误差为2.80%,经济材平均系统误差为1.43%;二元出材率表主要材种胶合板原木平均系统误差为-0.72%,造纸原木平均系统误差为1.12%,经济材平均系统误差为0.24%,各项检验指标均在误差范围内。以35株检验样本的造材数据主要材种出材率实测值与编表理论值进行置信椭圆F-检验的结果表明,胶合板原木、造纸原木、经济材的F-统计量分别为1.99、0.18和0.73,均小于F_(0.01)(2,32)的临界值5.34。研究结果表明,以d/D=[(H-h)/(H-13.)]^(f(D,H,h))为模型进行理论造材,可以编制精度较高的巨尾桉材种出材率表。

Taking 138 sample trees of plantation grown Eucalyptus grandis×E.urophylla from Shuangjiang County,Lincang City,Yunnan Province as the research materials,103 samples were tabulated and 35 samples were tested.These samples were evaluated using 8 selected taper equations commonly used in China and other countries.SPSS software was then used to perform nonlinear regression analyses to fit taper equation parameters based on data collected from the sample trees,and then compare results to current domestic yield tables.The deviation,absolute deviation,relative mean variance and average relative deviation between the correlation index and the measured values of tree diameters at certain heights and the theoretical values of cutting equations were compared and analyzed as evaluation indicators.Results showed that among the 8 alternative taper equations,the equationd/D=[(H-h)/(H-3.1)]^(f(D,H,h))provided the highest accuracy and correlation index(R^(2))of 0.97957,revealing it to be suitable for compiling the best taper equation for a E.grandis×E.urophylla species yield table.In order to determine the taper equation table,establish a regression equation of bark diameter and bark proportion,carry out theoretical timber production,a species timber yield table was compiled based on the sample data obtained.The results of the table compilation accuracy test showed that the average system error of the main wood plywood logs of E.grandis×E.urophylla was-0.06%,the average system error of pulp logs was 2.80%,and the average system error of economic logs was 1.43%;The average system error of the main types of plywood logs in the lumber rate table was-0.72%,the average system error of pulp logs was 1.12%,and the average system error of economical logs was 0.24%.All inspection indicators were within the error range.The results of the confidence ellipse F-test with the actual measured value of the main species yield and the theoretical value of the compiled table of the material data of 35 test samples show that the F-statistics of plywood logs,pulp logs,and economic logs are 1.99,0.18 and 0.73 respectively,all of which were smaller than the critical value of 5.34 for F_(0.01)(2,32).The results of the study show that,by using the variable parameter taper equationd/D=[(H-h)/(H-3.1)]^(f(D,H,h))as a model for theoretical lumber production,it is possible to compile a high-precision E.grandis×E.urophylla lumber yield table.