An Expression of Diameter Distribution for Unbalanced, Uneven-Aged Stands and Forests

From an analysis of records from more than 1,000 acres of northern hardwoods in the Northeast, a method was developed for expressing the size distribution of unbalanced, uneven-aged stands. The expression is based upon the finding that quotients between number of trees in successive4-inch dbh classes plotted over the midpoints between dbh classes form an ascending straight line. A given diameter distribution can be expressed by the slope b and intercept a of this linear relationship; conversely, these terms can be used to construct given diameter distributions for anygiven stand density. The slope b is highly correlated with a, percent distribution of basal area by size groups, and numbers of trees per acre; hence, b serves as a useful basis for segregating northern hardwood stands into structural groups that reflect differences in those characteristics.Preliminary information indicates that this expression may be applicable under stand conditions other than those included in this study.