THE POSSIBILITIES AND LIMITATIONS OF SILVICULTURAL TREATMENT IN PLANTATIONS IN SOUTH AFRICA

The methods employed in the construction of new metric volume and percentage utilization tables for Eucalyptus grandis, based on 1 378 sample trees are described. Most of the complicated volume calculations were executed on a computer. Because of this, the formula for a frustum of a cone was used to calculate volumes of log sections. The logarithmic volume equation was used for the construction of the general volume table. It was found that bark thickness had a significant effect on the variation of tree volume. Therefore, volume tables for various bark thickness classes have been prepared in addition to a general table for average bark thickness. The relationship between breast height diameter and the percentage of the total volume to 2 inches tip represented by a given tip diameter class can be explained satisfactorily by regression of the probit transformation of the percentage volume on a polynomial of the reciprocal of breast height diameter. For metric conversion, the tip diameter class was introduced as an additional variable and the relationship was expressed by one equation for all the tip diameter classes combined. Imperial as well as metric equivalents of all equations established are given.