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一个林区一般都生长着几个甚至几十个树种的林木。在具体林分中,有的为纯林,有的则为混交林。为调查立木材积,一般都编制地方性一元材积表。这种材积表又可分两种:一种是多树种混合材积表,如过去东北地区用的针叶树材积表和阔叶树材积表;另一种是分别树种编制的单一树种材积表。前者简便,但误差较大。如根据我们的分析,在直径相同时,榆树的材积仅为山杨材积的77.6%,黑桦材积仅为枫桦材积的79.8%;后者精度较高,但由于表格过多,容易造成混乱而出现错误。因此,在一个林区范围内,有必要编制出一套具
A forest area generally grows with a few or even dozens of tree species. In the concrete stands, some are pure forests, while others are mixed forests. In order to investigate the stand volume, a local one-dimensional volume chart is generally prepared. This volume table can be divided into two kinds: one is a multi-species mixed volume table, such as the northeastern region used in the past, the coniferous volume table and broad-leaved tree volume table; the other is a separate species compiled single tree volume table. The former is simple, but the error is larger. According to our analysis, when the diameter is the same, the volume of the elm is only 77.6% of the volume of the aspen and the volume of the black birch is only 79.8% of the volume of the maple and birch; the latter has high precision but is easily confused due to too many forms An error occurred. Therefore, in a forest area, it is necessary to compile a set of tools