Stem growth per unit of leaf area: a measure of tree vigor.

The ratio of basal area growth to sapwood basal area is shown to correspond with stemwood-volume production per unit of leaf area. Analyzing 122 healthy Douglas-fir in one stand showed this ratio to be consistent among all but suppressed trees. Evaluating other stands suggests the ratio may be sensitive to environment and reflect competition. This ratio of tree vigor will aid silviculturists in determining optimum stocking or in maintaining a stand at a selected level of vigor. FOREST SCl. 26:112-117.