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系统抽样是森林抽样的基本方法,是各种抽样方法的基础。系统抽样标准误通常借用随机抽样公式计算。由于样本单元分布较均匀,系统抽样精度常较随机抽样高。据文献报道,在林分比较整齐,即在一定范围内差异较小的森林中作等距离抽样配置时,标准误的估计约偏高30％。因此,在无偏差的条件下,由于系统抽样用随机抽样公式高估了标准误,结果必然加大抽样工作量。为解决这个问题,我们于1973年在东方红和迎春林业局进行了利用相邻
System sampling is the basic method of forest sampling and is the basis of various sampling methods. The systematic sampling standard error is usually calculated by random sampling formula. Due to the uniform distribution of sample units, the sampling precision of the system is often higher than that of random sampling. According to the literature, when the stands are relatively neat, that is, the equidistant sampling arrangement in the forest with a small difference within a certain range, the standard error is estimated to be about 30% higher. Therefore, under the condition of no deviation, due to the overestimation of standard errors by random sampling of system sampling, the sampling workload will inevitably increase. To solve this problem, we carried out in 1973 in Dongfanghong and Yingchun Forestry Bureau using adjacent