Direct Sampling for Stand Density Index

A direct method of estimating stand density index in the field, without complex calculations, would be useful in a variety of silvicultural situations. We present just such a method. The approach uses an ordinary prism or other angle gauge, but it involves deliberately “pushing the point” or, in some cases, “pulling the point.” This adjusts the usual limiting distances in prism sampling to match the limiting distances required for sampling with a specified stand density factor (SDF). The estimate of stand density associated with a point is just the number of trees tallied times the SDF; no diameter measurements are needed. We give guidelines on choosing an SDF on the basis of expected stand characteristics and equations for calculating the limiting distances and the amount of “push.” Field implementation of the resulting method is extremely fast and simple.