点抽样误差来源的研究

利用计算机模拟角规、角规观测和每木实测的方法,进行了不同角规常数的点抽样试验比较。结果表明:点抽样估计林分断面积是无偏的,而估计林分每公顷株数效率不高。点抽样的偏差主要是因漏计、角规常数选择不当,林缘效应等原因引起的。同时,还就如何防止点抽样产生偏差的技术措施提出了一些建议。

Study on Source of Error in Point Sampling

This paper compares three methods——computerized simulativevariable plot,angle counting,criusing and tally.An experiment of point sampling with different basal area factors (F) was conducted.The results indicated that it is unbiased to estimate basal area of stand but inefficient when estimating stems per hectare by point sampling.The bias in estimation results from lower counting of trees,unsuitable F,the effect of forest border or ect..Further,this paper presents several technical suggestions on how to prevent bias when using point sampling.