Mid-rotation Patterns of Change in Developing Mixed-oak Stands
Open Access
- Author:
- Stein, Benjamin Silas
- Graduate Program:
- Forest Resources
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 05, 2012
- Committee Members:
- Kim C Steiner, Thesis Advisor/Co-Advisor
- Keywords:
- oak
red maple
competition
stand dynamics
mid-rotation - Abstract:
- Oak species (Quercus spp.) are becoming less prevalent in the Eastern forest landscape that they formerly dominated. One apparent reason for the decline in oaks is the increase in competition from more mesophytic species such as red maple (Acer rubrum L.). Characteristics of red maple’s growth and development give it an advantage over oak species following harvest resulting in a transition from an oak-dominated composition to a mixed or red maple-dominated composition. However, there is uncertainty about whether red maple can sustain an initial advantage in density and abundance through the entire stand rotation. In this study, we examine the composition of 46 formerly oak-dominated stands in central Pennsylvania, across three main physiographic regions. Prior to harvest, the stands had an average of 80% of their basal area in oak species, and oak made up over 45% of the basal area in every stand. We used data from these stands measured an average of 24.7 years (range 21-33) following clearcut harvest and, again, an average of 37.8 years (range 35-43) after harvest to study the changes in composition and structure. Of particular interest was the interaction occurring between the major oak species and their primary competitor, red maple. Between the two measurements, oak’s relative basal area increased by 6.8, 4.6 and 0.5 % in the Blue Ridge, Ridge and Valley and Appalachian Plateau regions, respectively. Red maple, on the other hand, decreased 5.2, 0.3, and 12.7 %, respectively. The relative density of the oak group increased 20.8, 9.3, and 1.6%, respectively, while red maple relative density decreased 2.1% in the Blue Ridge and increased 4.2 and 6.8% in the Ridge and Valley and Appalachian Plateau, respectively. The oak species averaged an 11.4, 5.6, and 2.0% increase in proportion of upper canopy occupied by its stems. Conversely, red maple experienced a 9.4, 2.4, and 18.9% decrease in the proportion of upper canopy occupied by its stems. Despite red maple’s tendency to dominate stands following harvest there is evidence to support a shift in the growth of oak species and a decline in red maple that occurs decades after harvest. The change in composition and structure of the stands is a movement towards pre-harvest conditions which were predominantly oak. The cause of these changes appears to be differences in inherent growth characteristics; however, it is unlikely that many of these stands will regain the dominance expressed prior to harvest.