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A Log Volume Formula for Exporters
Authors: J.C. EllisPublication: New Zealand Journal of Forestry, Volume N.Z.J.For. 2011, Issue N.Z.J.For. 56(3) 2011, pp 20-26, Nov 2011
Publisher: New Zealand Institute of Forestry
Abstract: This paper shows that the volume estimate of export logs would be more accurate using a taper value in the 3D formula than volumes derived from the presently used Japanese Agricultural Standard. The 3D formula with a taper term based on small-end diameter and length was derived and tested on a data set of 9163 radiata pine logs measured between 2003 and 2010. Tests showed no error trends on log length or diameter, and the total volume was estimated to be within -0.1% of the 3D volume. Two further data sets, collected between 1946 and 1980, were used to test the formula on sectionally measured logs from older age classes and un-thinned stands. Overall the formula showed a small volume bias of +1.1% on 35281 radiata pine logs, and a bias of +4.3% on 5733 Douglas fir logs. Although some error trends were evident, the volume estimates were satisfactory over the range of export log dimensions. It is shown that the new (2D) formula shows less volume bias and smaller error trends on diameter and length than the JAS and Chinese National formulae.