Point-Sampling and Line-Sampling: Probability Theory, Geometric Implications, Synthesis.

摘要

Foresters concerned with measuring tree populations on definite areas have long employed two well-known methods of representative sampling. In list or enumerative sampling the entire tree population is tallied with a known proportion being randomly selected and measured for volume or other variables. In area sampling all trees on randomly located plots or strips comprising a known proportion of the total area are selected and measured for volume or other variables. List or enumerative sampling is commonly used in timber sales employing sampletree measurement, and area sampling in timber reconnaissance. Each method, in its simplest valid form, operates to give every tree in the studied population an equal chance of being selected. A class of trees, therefore, can expect to be sampled in proportion to the frequency of trees in that class, and the frequency of a single tree is one. Modifications of the above two techniques are usually designed to avoid sampling an identical proportion of trees in every class, since many classes are of slight interest but great frequency.