Comparison of Optical Dendrometers for Prediction of Standing Tree Volume

Abstract

Abstract Enhanced sets of compatible stem profile equations were used with data collected from felled and standing pine trees to calculate tree volumes to various top merchantability limits. Standing trees were measured with the Criterion 400 Laser, Tele-Relaskop, and Wheeler Pentaprism. These measurements were used to compare accuracies of the optical dendrometers for the measurement of tree dbh and height and the prediction of tree volume from stem profile equations. The Criterion 400 Laser was more accurate for dbh and total height measurement than was the Tele-Relaskop or the Wheeler Pentaprism, but the accuracy differences are not significantly different in a practical sense. Mean percent differences in dbh measurement translated, in absolute units, to -0.05, +0.20, and -0.34 in. of the mean tree dbh for the Criterion 400, Tele-Relaskop, and Wheeler Pentaprism instruments, respectively. Mean percent differences in total height measurement translated, in absolute units, to 0.5, 1.6, and 1.7 ft, respectively, of the average tree height and were not practically different. The combined measurement data for dbh and dob16, indicated the Tele-Relaskop would produce more reliable volume results than the other instruments if the dendrometer measurements were used with form class volumes. Profile equations developed with felled-tree data produced the most consistent estimates of merchantable height and cubic foot volume to specified merchantable top limits. In general, the Criterion 400 produced the smallest mean differences in standing tree measurements and profile equation predictions of merchantable height and cubic foot volume. However, the Tele-Relaskop produced the most consistent tree measurement and profile prediction trends. The Wheeler Pentaprism was the least accurate of the three dendrometers. South. J. Appl. For. 23(2):100-107.