杨梅人工林相容性单株生物量模型构建

  目的  构建杨梅Myrica rubra一元相容性单株生物量模型，为杨梅人工林可持续经营及生物量精确估测提供理论依据。   方法  基于48株杨梅标准木实测数据，在以地径、树高、冠幅为自变量建立独立单株生物量模型基础上，运用非线性误差变量模型法，对浙江仙居县杨梅人工林相容性单株生物量模型进行研究。   结果  拟合出的独立单株生物量模型中，以地径(x₁)为自变量的幂函数模型决定系数为最大，叶片生物量(y₁)、枝干生物量(y₂)、根系生物量(y₃)及总生物量(y₀)模型分别为y₁=0.004x₁2.795、y₂=0.003x₁3.048、y₃=0.002x₁3.141和y₀=0.010x₁2.995。以地径、树高、冠幅构建的3个相容性单株生物量模型拟合效果均较好，其中又以地径为自变量的模型决定系数和预估精度最大，模型最优，相关参数c₀、b₀、r₁、r₂、r₃和r₄分别为0.084 0、2.162 7、0.780 0、0.779 9、0.224 3和0.204 5。随地径、树高和冠幅增大，叶片、枝干、根系生物量的分配规律基本相似，枝干、根系生物量占总生物量的比例呈上升趋势，叶片生物量则逐渐下降。各组分生物量随杨梅林龄增大从大到小快速演变为枝干、根系、叶片。   结论  在运用杨梅一元相容性单株生物量模型进行估算时，以地径为自变量的幂函数模型决定系数最大，且模型决定系数和预估精度最大。地径是最适合用于估算杨梅生物量的变量。 图1表4参31

Construction of compatible individual tree biomass model of Myrica rubra plantation

  Objective  The purpose is to construct an individual tree biomass model of Myrica rubra, so as to provide a theoretical basis for sustainable management and accurate biomass estimation of M. rubra plantation.   Method  Based on the data of 48 M. rubra samples and the independent individual tree biomass model established with ground diameter, tree height and crown breadth as independent variables, the compatible individual tree biomass model of M. rubra plantation in Xianju County of Zhejiang Province was studied by using the nonlinear error variable model.   Result  The power function model with ground diameter (x₁) as independent variable had the maximal R2, and the models of leaf biomass (y₁), branch biomass (y₂), root biomass (y₃) and total biomass (y₀) were y₁=0.004x₁2.795, y₂=0.003x₁3.048, y₃=0.002x₁3.141 and y₀=0.010x₁2.995 respectively. The model with ground diameter as independent variable had the maximal R2 and accuracy, and the relevant parameters of c₀, b₀, r₁, r₂, r₃ and r₄ were 0.084 0, 2.162 7, 0.780 0, 0.779 9, 0.224 3 and 0.204 5 respectively. The distribution law of leaf, branch and root biomass was basically similar with the increase of ground diameter, tree height and crown width. The proportion of branch and root biomass in the total biomass was increasing, while the leaf biomass was gradually decreasing. With the increase of stand ages, the biomass of each component evolved rapidly to branches, roots, and leaves in descending order.   Conclusion  When using the individual tree biomass model of M. rubra with unitary compatibility for estimation, the power function model with ground diameter as independent variable has the largest determination coefficient and estimation accuracy. Ground diameter is the most suitable variable for estimating M. rubra biomass. Ch, 1 fig. 4 tab. ref. 31]