Integrated Stand Growth Model (ISGM) and Its Application

The Integrated Stand Growth Model (ISGM) is a prototype for pure even-aged stand which includes several nonlinear simultaneous equations: 1) basal area growth model; 2) self-thinning model; 3) dominant tree height growth model or site index curves; 4) relationship between average tree height and dominant tree height; 5) form height model and density index definition; basal area formula; stand volume formula. A new parameter estimation method of two-stage error-in-variable model (TSEM) for nonlinear simultaneous equations is used to estimate the parameters of ISGM to ensure the parameter estimation is unbiased and all the variables in the equations are compatible. The ISGM can be used to simulate pure even-aged stand growth with different values of site index, stand density, different thinning methods, and to draw a stand density control chart with the ForStat software (in Chinese) and in the Capsis platform (in English). The parameter estimation and simulation method are given in this paper.