Stem Diameter

Abstract

Stem diameter declines progressively from the base of the stem, as the tree tapers. So, a standard convention has been adopted in forestry to make a basic measurement of tree stem diameter at breast height. This is defined as being 1.3 or 1.4-m vertically above ground from the base of the tree. The height used varies in different countries (and, in America, is actually defined in imperial units as 4 ft 6 in); the difference is generally ignored when results from different countries are compared. If the tree is growing on sloping ground, breast height is measured from the highest ground level at the base of the tree. Loose litter and debris at the base of the tree should be brushed aside before making the measurement of breast height. Of course, stem diameters may be measured also at heights along the stem other than breast height; reasons for doing so are discussed in Sect. 5.3.4.