Crown class dynamics of oaks, yellow-poplar, and red maple after commercial thinning in appalachian hardwoods: 20-Year results

Abstract

Silvicultural strategies are often planned to favor the growth and survival of desired species until they reach a competitive position in the upper canopy. Once desired species reach the upper canopy, they can persist and provide a variety of benefits for decades. Later, they can serve as a source of natural regeneration for sustaining species composition. Although information is available for promoting desired advance seedlings in the understory of mature stands and culturing desired saplings in the upper canopy of young stands, additional information is needed on promoting desired species at mid-rotation, when the stand first reaches commercial size classes. Crown class transition rates for a total of 2, 668 white and chestnut oaks, northern red oak, scarlet and black oaks, yellow-poplar, red maple, blackgum, and black birch were observed for 20 years in a 53-year-old central Appalachian mixed-hardwood stand. Treatments included three residual stand densities after commercial thinning and an unthinned control. In general, the thinning treatments reduced mortality, increased crown class retention rates of codominant trees, and increased the ascension rates of trees in the intermediate crown class. After thinning, codominant trees exhibited the crown class stability of dominant trees, and intermediate trees exhibited greater survival and ascension to the upper canopy compared with unthinned controls. Very few suppressed trees improved canopy position in thinning treatments; however, thinning did tend to reduce mortality of these trees. Crown class transition rates are presented to help forest managers understand how commercial thinning treatments can affect the composition of the upper canopy in the latter stages of stand development. © 2009 by the Society of American Foresters.