Comparison of stand density measures in even-aged regrowth eucalypt forest of southern Tasmania

Abstract

Most of the existing measures of density of even-aged forests are estimates of the degree of approach of a stand to a "maximum density" condition. The measures differ in the way in which these estimates are made. The definition of maximum density may vary with forest type and the purpose for which the measure of density is to be used. In the present work, 17 different density measures are computed for sets of thinned and unthinned stands of regrowth eucalypt forest in southern Tasmania. The various measures are all presented in mathematically equivalent forms so that the relationships between them can be easily seen. Stands at maximum density are defined as those undergoing substantial and continuing competition-induced mortality. This contrasts with much other work in which "normal" stands are considered to be at maximum density. Reasons for the different approach to maximum density with the present forest type are discussed. The 17 density measures are found to fall into four groups (i) stand basal area itself, (ii) other measures based on sums of tree diameters, (iii) measures based on sums of tree volumes, and (iv) measures based on sums of tree heights. Many of the more complex measures are shown to have little appreciable difference from their simpler counterparts in the way they represent density.