用干形测定单株立木材积的再研究

单株立木材积的测定对林业生产和科学研究工作有着重要的作用,主要的方法是通过测定胸径、树高、上部直径或上部直径的高度来计算干形指数,然后计算材积。因不同的方法所用上部直径不同。所以本文用5个树种的解析木,分别对较常见的5种测定方法的测定精度进行了研究。得出的结论为：高径比大的树种,3／4形点法精度较高;高径比中等的树种,√0.5形点法、胸高形率法精度较高;高径比小的树种,绝对形率法、望高法精度较高。或者说：高径比越大,上部直径测定点相对越低。

RE-STUDY ON METHOD FOR A SINGLE TREE`S VOLUME BY MENSURATING TREE`S FORM

The mensuration of single tree's volume has important role in forestry production and research. The main methods is to compute the shape index of the tree trunk by mensurating tree's chest high diameter,upper diameter or height of upper diameter, then compute the tree's volume. Because every method use the different upper diameter, this paper using analytic trees of 5 kind trees study the precision of 5 common methods. The result is as follows: the precision of zhangmingtie method is higher when the ratio of height and chest high diameter is greater; the precision of Xuzenxiang method and Schifer method is higher when the ratio of height and chest high diameter is medium; The precision of Pressler method and Jonsion method is higher when the ratio of height and chest high diameter is smaller.the greater ratio of height and chest high diameter, The lower measuring point of upper diameter is.