森林生态效益的线性联立方程组模型的研究

摘要/Abstract

摘要： 在森林生态效益似乎不相关模型的基础上,分析众多生态效益中的相互依存和从属关系,引入内生变量Y₁、Y₂作为另一个生态方程的自变量,构造联立方程组模型.该模型比较深入地刻画了在森林生态效益因变量集中,以森林涵养水源效益为主导,与其它生态效益间的支配关系.从森林生态效益自身规律出发,构造联立方程组结构参数矩阵B和Γ,根据其中隐含的参数间约束条件,生成线性限制方程HA=L,是确保本森林生态效益联立方程组模型成功的关键.特别是对森林生态效益因变量与自变量非线性关系的分析,为森林生态效益联立方程组模型的构造奠定科学基础.本模型是过度可识别且误差结构矩阵不是对角矩阵的联立方程组模型.用三步最小二乘估计法的Matlab程序,得森林涵养水源、森林固土、森林保肥和森林防风固沙效益联立方程组模型,平均精度可达80%以上.由此估计出全国2000年的森林涵养水源生态效益量为4 227×10⁸t;森林固土效益量为3.9×10⁸t;森林保肥效益量为4.7×10⁸t;森林防风固沙量为22.8×10⁸t.

关键词: 森林生态效益, 联立方程组, 过度可识别, 三步最小二乘估计

Abstract: Based on the similar irrelative model of forest ecological benefits,the study analyzed the subordinate relations of numerous ecological benefits,and introduced end genetic variables Y₁ and Y₂ as the independent variables of another ecological equation to construct consociation equation set model.Leading from the forest's water absorption benefits,it deeply depicted the dependent and subordinate relations between the forest ecological benefits dependent variable set.Staring from the basic rule of forest ecological benefits,constructed the consociation equation set structure parameters matrix B and Γ restricted by parameter to get linear limit equation HA=L,which is the key to the forest ecological benefits consociation equation set.Especially,the study on the non-linear relation of forest ecological benefits dependent and independent variable was the foundation of forest ecological benefits consociation equation set.The model was excessiveness identified and error structure matrix,not cross matrix.The forest absorbing water and stabling soil and keeping fertilizer and defending sand benefits estimate equations were gotten through the three steps least square estimation method with Matlab program,and the average precision was morn than 80%.From this method,the whole country forest absorbing water benefit was estimated as 4.7×10⁸ t,forest fixing soil benefits was 39×10⁸ t,forest keeping fertilizer benefit was 4.7×10⁸ t and defending sand benefits was 22.8 ×10⁸ t.

Key words: Forest ecological benefits, Consociation equation set, Excessiveness identification, Three steps least square estimatation

中图分类号:

S718.5

郎奎建. 森林生态效益的线性联立方程组模型的研究[J]. 应用生态学报, 2004, (8): 1323-1328.

LANG Kuijian. Linear consociation equation set model of forest ecological benefits[J]. Chinese Journal of Applied Ecology, 2004, (8): 1323-1328.

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