%0 Research note
%T Parameter estimation of nonlinear growth models in forestry
%A Fekedulegn, Desta
%A Mac Siurtain, Mairitin P.
%A Colbert, Jim J.
%D 1999
%J Silva Fennica
%V 33
%N 4
%R doi:10.14214/sf.653
%U https://silvafennica.fi/article/653
%X Partial derivatives of the negative exponential, monomolecular,  Mitcherlich, Gompertz, logistic, Chapman-Richards, von Bertalanffy,  Weibull and the Richard’s nonlinear growth models are presented. The  application of these partial derivatives in estimating the model  parameters is illustrated. The parameters are estimated using the  Marquardt iterative method of nonlinear regression relating top height  to age of Norway spruce (Picea abies L.) from the Bowmont Norway Spruce  Thinning Experiment. Formulas that provide good initial values of the  parameters are specified. Clear definitions of the parameters of the  nonlinear models in the context of the system being modelled are found  to be critically important in the process of parameter estimation.