Age-and-Vigor Classes in Relation to Timber Marking

Classified growth tables designed to guide timber marking are presumed to indicate growth possibilities after cutting. The biological characteristics of each tree class are presumed to be the cause of rapid or slow growth. Experience in the Southwest points to much confusion between cause and effect. Large crowns have been regarded as necessary for rapid growth, whereas they are really an effect of the same factor that produces rapid bole growth, namely, soil moisture as determined by ground space.