桉树生物量估算模型及与IPCC法的对比分析

Allometry Equations for Estimating Eucalyptus Tree Biomass and Comparison with IPCC Method

为构建适用于区域桉树人工林生物量异速生长方程,收集整理桉树林的生物量文献数据,拟合测树因子(胸径和树高)与地上、地下和单株生物量间的回归关系。结果表明:单自变量模型中,基于胸径因子的方程拟合优度高于树高因子。双自变量模型中,树高因子的添加仅对单株生物量拟合优度提高了0.7%～1.5%。模型的预测值与实测值的比较及相容性分析表明,方程lnW=-2.833+2.301ln D+0.352 1lnH对地上生物量预测效果最优,精度达94.6%;方程lnW=-5.175+0.939ln D^2H对地下生物量预测效果最优,精度达66.8%;方程lnW=-2.960+0.896ln DH^2对单株生物量预估效果最优,精度达95.5%。分量模型与单株模型相容性较好。桉树人工林BCEF和R的平均值分别为0.634 1(n=65,SD=0.132)和0.205 6(n=76,SD=0.089)。IPCC法对林分生物量估算精度高于异速生长方程,达到95.3%。因此,建议采用IPCC生物量估算参数法进行区域尺度桉树人工林生物量估算。

In order to construct allometric equations for large scale Eucalyptus plantations,biomass data were obtained from published papers and subject to meta-analysis to obtain regression relationships of various factors with aboveground,belowground and total-tree biomass.The results showed that a single independent variable equation based on DBH performed better than one based on tree height.In double independent variable models,the use of tree height in combination with DBH only improved the R2 of total-tree biomass by 0.7%to 1.5%,but did not improve correlations obtained with other component equations.Verification analysis of predicted and measured values of the models showed that the equation lnW=-2.833+(2.301*lnD)+0.3521*lnH has the best predictive ability for aboveground biomass with an accuracy of 94.6%,while lnW=-5.175+0.939*lnD^2H has the best predictive ability for underground biomass with a correlation of 66.8%,and lnW=-2.960+0.896*lnDH^2 has the best predictive ability for total-tree biomass with a correlation of 95.5%.The derived component model was comparable with total-tree biomass model.The means of BCEF(Biomass Conversion and Expansion Factor)and R(Root:shoot Ratio)were 0.634(n=65,SD=0.132)and 0.206(n=76,SD=0.089),respectively.The accuracy of the forest biomass estimation by the IPCC method was higher than that of the allometric equation,which was 95.3%.Therefore,it is recommended to use the IPCC(Intergovernmental Panel on Climate Change)method for estimating the biomass of Eucalyptus plantations on regional scales.