Taper curves (i.e., functions describing the shape of a tree stem) can be used for conveniently computing the volume of a tree stem, using volume integrals, but they are not very commonly used in ecological research. The curves and their volume integrals are particularly convenient for computing the volume of snapped trees, where the shape of the stem (taper) is determined by the tree diameter and the height of the tree before snapping, and the volume is computed from the base of the tree to the snapping height (or any other point along the stem). Same functions can be used to compute the volume of a fallen part of a snapped tree just as easily.
We’ve written an easy-to-use R-script for several tree species in regions we are working in, based on previously published taper curves: Scots pine, Norway spruce, and birch in Finland, as well as black spruce and balsam fir in Quebec, Canada. Take a look at the script here.