The Estimation of Stem Taper Curve from the Radial Information at Three Locations on the Stem

摘要

This paper presents a method that the stem taper curve of standing tree can be estimated with a considerable precision without the taper table. The stem taper curve used is 3 degree polynomials that is stated an effective equation. The parameters of this e-quation are generally decided by the least squares method from diameter measured values at several or many locations on the stem, but can be decided by the simultaneous equations or the least squares method in mathematical stand point if the diameter measured values on the three optional locations can be obtained. Then about which locations on the actual stem to select as diameter measurement for finding out more approximated stem taper curve to the actual stem taper curve from three diameter measured values is studied in this paper. Data used here are the diameter measured values at each location on the stem in sample trees sampled from the stands of Pinus sylvestris var. mongolica. The estimation of best stem taper curve by the least squares method using the radial information at nine locations ( Method -I ), and of stem taper curve using only the radial information at three locations ( Method -II ) from these data were carried out. As a result, it is suggested that the combinations of radialinformation of six kinds are effective from the precision compared with that of Method- I . Moreover, it is suggested that three combinations among these radial information, i.e. ,(r_(1.3), r_(0.3), r_(0.7), (r_(1.3), r_(0.4), r_(0.7) and (r_(1.3), r_(0.4), r_(0.8)) are more effective than remaining three combinations.