A test of the delayed oak dominance hypothesis at mid-rotation in developing upland stands

Abstract Red maple often dominates tree regeneration following the harvest of upland oak stands in eastern North America. An open question is whether the oak component of the new stands will eventually reassert dominance (delayed oak dominance hypothesis) or whether red maple will succeed as a major, new overstory component on these sites (red maple dominance hypothesis). We examined changes between the 3rd and 4th decades of growth (mean interval 13 years) in 46 stands on formerly oak-dominated sites in the Blue Ridge (BlRi), Ridge and Valley (RiVa), and Appalachian Plateau (ApPl) physiographic provinces of the central Appalachians. Almost without exception, the new stands in their 4th decade (mean age 38 yrs) had less oak and more red maple than did their predecessors. All ApPl stands had failed to develop a substantial component of oak early in stand development, and most were dominated by red maple in their 4th decade. Most BlRi stands had become dominated by oak by their 4th decade, and changes between the 3rd and 4th decades show that oak is progressively becoming more dominant by displacing the relatively minor component of red maple that remains. The success of oak was generally intermediate in the RiVa, where red maple retained an approximately co-equal position of dominance with oak between the 3rd and 4th decades and in some stands advanced in dominance against oak. We suggest a nuanced interpretation of delayed oak dominance as an emergent and contingent property of individual trees and their neighborhoods. Both this and red maple dominance accurately describe developmental trajectories that are co-occurring in most of our stands, with one predominating over the other depending upon physiographic region and site-related characteristics. In general, development favored oaks where growth rates were slower and where species composition was more xerophytic. Red maple was favored on better sites, where delayed oak dominance appears to be a longer and ultimately less successful process.