Scaling of Teak (Tectona grandis) Logs by the Xylometer Technique: Accuracy of Volume Equations and Influence of the Log Length

The accuracy of ten methods of scaling (Smalian, Huber, Newton, Neloïd, paraboloid, cone, paracone, cylinder, truncated cone and truncated Neloïd) was evaluated on logs of 0.5, 1, 2 and 3 m cut to different heights of 27 teak trees. For this purpose, the volumes estimated by the ten formulas were compared with real volumes obtained by the technique of xylometer. The results obtained showed that the method of Huber was more efficient to calculate the volume of logs throughout the stem when the length was 0.5 m. For the other length logs, it was also the best formula when the logs came from the base of the stem. The formulas of Newton and Smalian gave in the center and top of the stem, in the case of 1 m and 2 m logs, relatively similar results and were better than other methods of scaling. As might be expected, the dendrometric method (cylinder, paraboloid, Neloïd, cone) gave worse results regardless of the length of logs considered. With logs of 0.5, 1, 2 and 3 m long, truncated forms of cone and Neloïd could also be used without significant errors in estimating the volume of teak logs. The model scaling obtained for the entire tree expresses the logarithm of the volume against the logarithm of the diameter and the logarithm of height.