Abstract

Stand models for mixed species stands based on static yield functions, transition matrices and difference equations are not satisfactory in many instances. Quite often they do not adequately incorporate information on species composition. A new model form is proposed which relates the increment in biomass or growing stock to present species composition. Proportions of the growing stock in the various species are incorporated into a regression-type model as predictors with the use of a class of Scheffe's canonical polynomials. Since the species composition can exist under different stocking levels, the initial stocking levels become process variables (cornell 1981) . Stand top height can be used as a self-calibrating variable to account for productivity variations in different stands