Simulation of Diameter Growth and Mortality in Regrowth Eucalypt Forest of Southern Tasmania

Author: West P. W.  

Publisher: Society of American Foresters

ISSN: 0015-749X

Source: Forest Science, Vol.27, Iss.3, 1981-09, pp. : 603-616

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Abstract

A single-tree, distance-independent simulation model to predict future diameter in unthinned, 20- to 80-year-old, even-aged regrowth eucalypt forest in southern Tasmania is described. The forest consists of pure and mixed-species stands of Eucalyptus obliqua, E. regnans, intermediates between these two species, and E. globulus. Regression equations relating diameter increments of individual trees of the various species to tree and stand parameters are determined. A regression equation to predict the probability of death of individual trees of a stand at any particular age is described; this function is used to simulate mortality as a stochastic process. Generalized least squares regression was used to compute these regression equations and the use of this technique is discussed. The diameter increment and mortality functions are tested by simulating growth of an independent set of test stands over periods varying from 3 to 21 years. The accuracy of estimates of future basal area and stocking of stands from these simulations is determined. The simulated and actual diameter distributions of the stands are shown to not differ significantly. Forest Sci. 27:603-616.