Minimum tree size and interpretation of stand structure in uneven-aged northern hardwoods

Uneven-aged management of northern hardwoods frequently relies on diameter distributions in evaluating and controlling stand structure. However, the minimum tree diameter used to analyze diameter distributions varies among studies and may affect the interpretation of distribution shapes and, subsequently, stand structure. It has been suggested that the use of larger minimum diameters in the construction of these distributions would cause rotated sigmoid stand structures to exhibit a negative exponential distribution shape. To test this hypothesis, we constructed diameter distributions using minimum diameters of 3.0 and 13.0 cm for seven northern hardwood stands. Differences in distribution shape were observed only in unmanaged stands, in which three distribution shapes classified as rotated sigmoid using a 3.0-cm minimum diameter were classified as increasing-q when the 13.0-cm minimum diameter was used.