森林资源二类调查系统抽样2种样地调查方法的比较与分析

Comparison and Analysis on Two Kinds of Sample Plot Survey Methods of Systematic Sampling in the Forest Inventory for Planning and Design

以贵州省锦屏县第四次森林资源二类调查系统抽样为例,对角规点抽样的标准表法和圆形样地每木检尺的二元立木材积表法进行了比较和分析。结果表明:角规样地与圆形样地对总体蓄积抽样精度分别为90.28%,90.38%,均达到规定的精度要求(≥90%),总体蓄积估计值仅相差1.63%;角规样地检尺样木株数较少,外业工作量相当于圆形样地的40%左右,抽样效率较高;角规样地对大部分林分公顷株数、公顷断面积、公顷蓄积的抽样估计偏低。小班蓄积采用角规辅助调查的标准表法,总体蓄积采用圆形样地每木检尺的二元立木材积表法进行抽样控制的方法是可行的。

This paper took systematic sampling as an example in the fourth forest inventory for planning and design in Jinping County of Guizhou Province,and the point sampling with angle gauge ＆volume standard table and circle-shaped sample tally ＆two-way tree volume table were compared and ana-lyzed.The results showed that the precisions of the volume estimates from the point sampling with angle gauge and circle-shaped sample tally were respectively 90.28%and 90.38%,exceeding 90% which is the precision standard of the technical specification for the forest inventory in Guizhou.The difference of total forest stand volume between two forest inventories was only 1.63%;The sample tree of the point sampling with angle gauge was less,but more efficient than the circle-shaped sample tally in sampling, and the load of field work of the former was about 40% of the latter;the number of trees per hectare, cross-sectional area at breast height of per hectare and hectare volume were lower than the circle-shaped sample tally in the precisions of estimates.Subcompartment volume cruise with angle gauge ＆volume standard table,systematic sampling with circle-shaped sample tally＆two-way tree volume table are appli-cable in the sampling control of total volume.