Shading affects date of budbreak in northern red, white, and shumard oak seedlings

摘要

During the spring of 1993 budbreak (initial elongation of the bud) was observed on 468 northern red, 357 white and 154 Shumard oak seedlings growing under 4 light levels - heavy, medium, and light shade and in full sunlight (30,50,70, and 100 percentof full sunlight, respectively). The average dates of bud break for the increasing light levels were: heavy shade -April 7; medium shade -April 9; light shade -April 11; and in the open (full sun) -April 14 . These findings indicate that bud-break patterns are significantly influenced by shading levels. Early bud-break under a canopy may help oak seedlings survive, however, when the canopy is removed, the buds continue to break early which may contribute to oak regeneration problems.