a quantitative measure of tree stocking, expressed either relatively as a coefficient, taking normal numbers, basal area or volume (from yield table data) as unity, or absolutely, in terms of number of trees, total basal area, or volume, per unit area, more precisely, a measure of the degree of crowding of trees within stocked areas, commonly expressed by various growing-space ratios - of crown length to tree height; crown diameter to d.b.h., or crown diameter to tree height; or of stem (triangular) spacing to tree height