Evaluating behaviors of factors affecting the site index estimate on the basis of a single stand using simulation approach
2008
Ni, Chengcai | Liu, Chunmei
Height observations H1 and H2 present on the right- and left-hand sides of site index models, respectively. The error terms associated with H1 and H2, along with parameter estimate errors, affect the estimate of the site index. Projection error variance (PEV), in a projection from A1 to A2, consisted of four components associated with H1, H2, the covariance of H1 and H2, and the parameter estimate errors. In this study, behaviors of these components were investigated via simulations on the basis of six equations derived from the Lundqvist-Kerf and the Hossfeld IV functions. Simulation results showed that projection interval, projection direction, and selected site-dependent parameter influenced PEV and its components. PEVs of backward and forward projections with the same projection interval lengths were remarkably different if the underlying model was anamorphic. With increasing projection interval length, the PEV of forward projections monotonically increased to a certain value, whereas the PEV of backward projections decreased to zero after reaching a maximum.
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