适于GlobalAllomeTree国际数据平台的标准化中国主要树种树高-胸径方程研建

Construction of A Standardized Height-diameter Equation for the Main Tree Species in China Suitable for the GlobalAllomeTree International Data Platform

GlobalAllomeTree作为共享异速方程的国际网络平台,逐渐受到全球高度关注。当前,为促进该项国际合作,针对当前该平台缺乏中国主要树种生长异速方程的现状,系统性更新标准化中国主要树种树高-胸径方程。由于树冠和下部灌木及草丛遮挡,树高相对于胸径测量具有一定的难度,因此需要使用数学工具进行计算。选取了36个树种为材料构建树高-胸径关系方程,以全国主要树种的二元材积模型、各地区一元材积表为基础材料,以取样径阶为1 cm间隔所生成1692组树高-胸径数据作为建立方程样本,1238组外业调查数据为验证样本。建模结果表明:36个主要树种的1692组树高-胸径数据建立的全国通用性树高-胸径方程拟合相关系数(R2)为0.801,方程拟合结果较好,说明可以通过测定胸径,带入树高(H,m)-胸径(D,cm)方程(H=aDb)预估树高;对36个主要树种的树高-胸径方程进行拟合,决定系数R2值均大于0.916,平均误差(ME)、平均绝对误差(MAE)和均方根误差(RMSE)相对较小,方程整体精度较高,可广泛推广;将外业采集的1238组树高-胸径数据,根据36个主要树种树高-胸径方程拟合公式及参数估计值a、b进行方程精度验证,方程预测的平均相对误差为16.86%,在误差允许范围内,并且模型形式规范,可为GlobalAllomeTree平台用户提供科学参考。

GlobalAllomeTree is an international network platform that shares differential equations,which has gradually received high global attention.Currently,aiming at the lack of growth differential equations for major tree species in China on this platform,this study updated the standardized tree height-diameter relationship equation for major tree species in China.Due to the canopy and lower shrubs and grass cover,the measurement of tree height relative to diameter at breast height(DBH)is difficult,so mathematical tools need to be used for regression calculations.36 tree species were selected as materials to construct a tree height-diameter relationship equation.Based on the binary volume model of major tree species in China and the one-dimensional volume table of each region,1692 sets of tree height-diameter data generated with a sampling diameter order of 1 cm interval were used as equation samples,and 1238 sets of field survey data were used as validation samples.The modeling results showed as followed:the correlation coefficient(R2)of the national universal tree height-diameter equation fitting based on 1692 sets of tree height diameter data from 36 main tree species was 0.801,indicating that the equation fitting results were good,so the tree height can be estimated by measuring the diameter at breast height(H,m)-diameter at breast height(D,cm)square H=aDb;using the equation to fit 36 main tree species,the results showed that the determination coefficients(R2)of the tree height-diameter at breast height equation for 36 main tree species were all greater than 0.916,and the values of mean error(ME),mean absolute error(MAE),and root mean square error(RMES)were relatively small.The overall accuracy of the equation was high,which could be widely promoted;using 1238 analytical tree data collected from field work,the accuracy of the equation was verified based on the fitting formulas and parameter estimates a and b of the tree height diameter equation for 36 main tree species.The results showed that the average relative error of the equation prediction was 16.86%,within the allowable range of error,and the model format was standardized.Above results provided scientific reference for users of the GlobalAllomeTree platform.