广西主要树种立木生物量模型的研建

Modeling of Standing Tree Biomass for Main Species of Trees in Guangxi Province

在广西境内收集杉木、马尾松、桉树、硬阔类、软阔类等树种333株,按收获法进行生物量测定,分别树种采用W=c1×Dc2,W=c1×(D2H)c2,W=c1×Dc2×Hc3模型进行地上部分生物量拟合,并采用加权回归估计消除模型的异方差,利用部分有根部生物量测定的样本,分别树种建立地下与地上生物量回归模型,获得平均根茎比参数。结果表明:1)采用W=c1×Dc2×Hc3结构建立地上生物量模型,具有较高的精度;2)通过加权回归后,地上生物量模型精度略有降低,但模型稳定性增强;3)主要树种地上生物量模型的决定系数R2均达到0.93以上,总相对误差(TRE)和平均系统误差(MSE)均控制在±1%以内,平均预估精度基本在94%以上,结合平均根茎比参数,可在一定径级范围内用于广西主要树种生物量估测。

A total of 333 trees from China fir, masson pine, eucalyptus, Hard broad-leaf and soft broad- leaved species growing in Guangxi province were collected and their biomass was measured by harvest method. Three equations, W=c1×Dc^2,W=c1×（D2H）c^2,W=c1×Dc^2×Hc^3 and W = cl x Dc2 x Hc3 , were applied to above-ground biomass （AGB） fitting of each tree-species group, and the heteroscedasticity of equations was eliminated by weighted-regression. Roots biomass of some tree samples were employed to model the equations of root-to-shoot ratios. The results showed that ： （ 1 ） the precision of AGB model based on W=c1×Dc^2×Hc^3was higher; （ 2 ） weighted regression slightly decreased the precision of AGB equations, but enhanced the stability of equations; （3） determination coefficients of AGB equations were greater than 0. 9 ,and the total relative error （TRE） and mean systematic error （MSE） were basically controlled within ＋ 1% ,then the estimate precision of biomass equations was about 94%. Therefore,combing with the equations of root-to-shoot ratios, these above-ground biomass equations were suitable to estimate the biomass of the major tree species of Guangxi in a certain range of diameter at breast height （DBH） class.