Linear simultaneous equations models of stand growth based on the permanent sample plots

To describe the factor relations of the two periods permanent sample plots (PSP) in continuous forestry survey, the paper analyzed the stand growth variables based on the observation materials in the years of 1990 and 1994.And then it introduced standard site index and linear transform according to the Borders model.Stand growth simultaneous equations model cluster (YB+xΓ=ε) was constructed based on the dominant tree species after an interval of five years.The model parameter matrices (B and Γ) were un-bias estimation.The simultaneous models were recognizable and their error structure matrices were not diagonal.The equations of stand basal area and volume in 1994 was an implicated function of the standard site index, stand age and initial basal area.The paper described the subordination and dependent relationship between the two periods PSP stand factors.Through the model external-test, the average precision of volume model was over 90% and the estimation precision of stand net growth was over 80%.The simultaneous models were well adaptive to estimate discrete data of stand yield and could describe the natural stand growth theoretically.