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6.11 Individual Tree Equations
Authors: A D Gordon, M van der ColffPublication: NZIF Forestry Handbook, Volume Section 6 – Data collection and projection, pp 11, Dec 2023
Publisher: New Zealand Institute of Forestry
Abstract: Stem volume and taper are both expressions of the change in the diameter of the stem from the base to the tip of the tree. The volume of an individual tree depends on its taper: the more rapid the taper, the less the volume. Traditional mensuration focussed on the prediction of total stem volume, but as systems for yield prediction improved, new methods of predicting taper (hence log volume and end diameters) were developed. To reconcile the inconsistent predictions from independent volume and taper systems, "compatible" taper equations were developed in which part of the system is conditioned to ensure the inherent relationship between volume and taper is not violated. The fact that, with a little care, volume can be derived analytically from a taper equation, has been used more recently to simplify and improve the solution, leading to the development of "composite" equations which simultaneously predict diameter over- and under-bark, volume over- and under-bark and bark thickness. The fact that, with a little care, volume can be derived analytically from a taper equation, has been used more recently to simplify and improve the solution, leading to the development of "composite" equations which simultaneously predict diameter over- and under-bark, volume over- and under-bark and bark thickness.