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用 f_(1·3)=q_2~2计算材积,只适应于树干形状近似抛物线形,即 r=1的树木,对形状各异的树木进行计算,往往精度低,偏差大,从而给科学研究和林业调查带来许多困难。为了提高立木材积的计算精度,1985—1990年,笔者开展了此项研究。通过对13个树种,121株解析木、伐倒木资料的计算分析,找出了用树高、中径、胸径确定树干曲线指数 r,进而用 f_(1·3)(r)=(1/(r+1))(H/(H-1.3))~r 公式计算胸高形数的方法。并验证得出:用 f_(1·3)(r)计算立木材积,精度高,偏差小,能适用于各种用材树种。同时,编制出了胸高形数表,用此表查找胸高形数,简而易行,可加快树木材积计算速度,提高计算精度。
Calculating the volume with f_ (1 3) = q_2 ~ 2 is only suitable for trees whose trunk shape is approximate parabola, that is, r = 1. Calculating trees with different shapes tends to have low precision and large deviations, And forestry investigation brings many difficulties. In order to improve the calculation accuracy of standing timber volume, from 1985 to 1990, the author carried out this research. Through the calculation and analysis of 13 tree species and 121 tree species, we found out the tree trunk curve index r with tree height, diameter and DBH, then use f 1 3 r = 1 / (r + 1)) (H / (H-1.3)) ~ r formula method for calculating the height of the chest. The results show that: Using f_ (1.3) (r) to calculate stand volume, high precision, small deviation, can be applied to a variety of timber species. At the same time, the preparation of the chest height table, using this table to find the chest high number, simple and easy to speed up the calculation of the volume of trees and improve the calculation accuracy.