西藏云杉立木生物量与材积相容性模型研建

利用2011年实测的西藏天然云杉立木生物量与材积数据,采用非线性度量误差联立方程组、分段建模方法,构建了云杉立木地上生物量与树干总材积、地下与地上生物量相容性模型,以及生物量与材积换算、根茎比模型,并分析对比建立的立木地上生物量与材积相容性整体模型与分段模型效果。结果表明:1)将胸径<5cm的幼树与>5cm林木一起进行整体建模,建立的一元和二元立木生物量整体模型预估值在12cm以下径阶产生明显偏差;2)选取合适的分段位置(D=10cm),采用分段建模方法建立的一元立木地上生物量分段模型各径阶偏差明显减小,二元分段模型无系统性偏差;3)研究建立的一元、二元立木地上生物量和材积相容性分段模型的总相对偏差均在±2.5%以内、预估精度均>91.2%,地下生物量分段模型预估精度也>92%。建立的分段模型可用于西藏云杉立木生物量和材积的估计。

Establishment of Compatible Single-Tree Biomass and Tree Volume Models for Spruce in Tibet

Based on measured data of single-tree volume and biomass of spruce occurring in Tibet in 2011,all the compatible models of above-ground biomass and tree volume,below-ground biomass and above-ground biomass,and biomass conversion models and ratio models of root and stem were constructed by using the nonlinear metric error-in-variable simultaneous equations and segmented modeling approach,and the fitting effect between integral models and segmented models were analyzed and compared.The results showed that 1) when the one-and two-variable-based integral models which were established by considering young spruce trees with DBH smaller and bigger than 5 cm to estimate the biomass of living trees were applied to the trees with DBH less than 12 cm,significant deviations were found.2) Based on the observation that all the sample data were divided into two sections around an appropriate DBH diameter,i.e., D =10 cm,segmented modeling method was adopted for the prediction of the biomass of living trees,from which the deviation of one-variable-based models was obviously reduced,and no obvious systematic deviation was found in two-variable-based models.3) The total relative deviations of one-or two-variable-based single- tree biomass equations established by using segmented modeling method was within the range of 2.5%,and the estimated precision was above 91.2%,the prediction precision of the below-ground biomass models was more than 92%,indicating that the single-tree biomass equations established by using segmented modeling method could be used to estimate the biomass and volume of spruce in Tibet.