RECONSTRUCTION OF THE COMPETITIVE DYNAMICS OF MIXED OAK FORESTS
Open Access
- Author:
- Heggenstaller, Dan James
- Graduate Program:
- Forest Resources
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 03, 2010
- Committee Members:
- Eric Zenner, Thesis Advisor/Co-Advisor
Eric Zenner, Thesis Advisor/Co-Advisor - Keywords:
- oak regeneration
competition
stem analysis
stand dynamics
oak - Abstract:
- Oaks are some of the most ecologically and economically important tree species in the eastern United States. Regeneration of oak-dominated stands has been problematic in this region, where young stands are often dominated by competitors such as red maple, sweet birch and black cherry. In some cases, young oaks may be eliminated early in stand development by these faster growing competitors, resulting in new stands where oak is only a minor component. Other evidence suggests oaks are able to persist, and eventually emerge as canopy dominants over these competitors. The goal of this study was to determine how the height growth dynamics of oaks and non-oak competitors differed during early stand development. Six oak-mixed hardwood stands in the Appalachian Plateau and Ridge and Valley regions of Pennsylvania were selected for this study. Each stand was systematically sampled to locate dominant and subordinate oaks with at least two adjacent non-oaks (red maple, sweet birch, and black cherry) of equal crown class. In each stand, 20 such neighborhoods were randomly selected for the study. Each tree cluster was mapped, and stem cross-sections were collected and aged every meter from below the root collar to the top of each tree to determine height growth patterns. Most oaks were found to have root systems older than their above ground stems, suggesting that these trees were seedling or sapling sprouts. Dominant chestnut oaks in the Ridge and Valley were never more than 1 meter shorter than neighboring red maple and 0.5 meters shorter than neighboring sweet birch. Chestnut oaks in the Ridge and Valley that fell further behind became subordinate and are not likely to survive much longer. On the Appalachian Plateau, dominant northern red oaks were never more than 2 meters shorter than black cherry and red maple, and 1.5 meters shorter than sweet birch. No northern red oaks that were more than 1 meter shorter than sweet birch or red maple at age 20 became dominant by age 30. In general, oaks that were significantly behind at age 15 were likely to become subordinate by age 30, implying release treatments must occur early (age 10-15), before oaks become overtopped.