EFFECT OF CROWN GROWING SPACE AND AGE ON THE GROWTH OF NORTHERN RED OAK

Cultural practices can be applied in even-age stands to reallocate site resources to selected crop trees. Precornrnercial thinning in sapling stands can increase diameter growth and improve species composition of trees in the main canopy. Commercial thinning in sawtimber stands also increases diameter growth of crop trees, improves residual stand quality, and removes trees that would die absent thinning. Silviculturists need quantitative information on the response of particular species to thinning treatments to meet specific management objectives. In this study, 7- to 80-year-old northern red oak (Quercus rubra L.) crop trees in unrnanaged, even-age central Appalachian stands were given various degrees of crown release. The response of released trees was compared to that of controls. Results of these individual trials, formerly published in numerous separate reports, are synthesized and combined with new information from more recent studies. Crown growing space, derived from the proportion of crown perimeter free-to-grow and distance to adjacent competing trees, is a significant independent variable that affects growth response. Crown growing space has a positive effect on dbh growth and crown expansion and a negative effect on height growth and length of clear stem. The impact of crown growing space d i s h e s with tree age, though sigmficant increases in dbh growth were observed for 80-year-old trees. Applications of crown release treatments might be usefbl in producing timber products, improving wildlife habitat, or in accelerating the development of old-growth and other desired stand conditions