In much of the eastern United States, oaks are declining, while generalist species such as red maple (Acer rubrum) are on the rise in historically oak-dominated forests. This shift is in part attributable to changing land use, including the suppression of low-intensity fire (which oaks are adapted to exploit) and the regrowth of formerly cleared lands (where disturbance-adapted, fast-growing species often outcompete oaks). Increased deer browsing pressure and spongy moth outbreaks may also contribute to this shift.
Conventional efforts to promote oak regeneration, such as prescribed burns and clearcutting, seem to be decreasingly effective. Adding to the challenge, most oak-related research and management has occurred on public land, while eastern oak forests are primarily privately owned. Because private forestlands are managed with a wide range of goals and techniques, silvicultural treatments meant for relatively large, centrally managed public forests may not be feasible on private lands, even though private owners’ management choices affect more of the landscape.
In a 2024 study published in the Journal of Environmental Management, researchers from University of Missouri, the U.S. Fish & Wildlife Service, and the U.S. Forest Service examined how management choices on public and private lands could change the long-term ecological trajectory of an oak-dominated forest in southeastern Ohio. The research team used a forest landscape model called LANDIS PRO to simulate 150 years of forest growth on 2.1 million hectares in the southern Appalachian Mountains, using species-specific traits including seed dispersal, survival, and shade-tolerance to predict shifts in forest composition and structure over the course of many generations. The model was “spatially explicit,” meaning it replicated the actual distribution of public and private ownership (as well as species composition and forest structure) across the landscape. In this case, about 80 percent of the forest was privately owned.
In the first of four model runs, both public and private forests experienced “business-as-usual” management, based on current forestry practices. In the second, both were managed using alternative approaches to encourage oak regeneration. For private forests, this meant doubling the amount of forest being actively managed each decade, changing selection practices to cut out maples and to preserve oaks, and preventing “high grading,” the selective removal of the most valuable trees in the forest (often mature oaks). For public forests, it meant using repeated shelterwood harvests and supplemental thinnings to remove maples from the midstory and to create an open, oak-dominated canopy. In the third and fourth scenarios, management was mixed, with one ownership type using the alternative approach and the other experiencing business as usual.
Under the business-as-usual scenario, oaks gradually declined across the entire landscape, while maples experienced a remarkable 400-percent increase in total basal area (a proxy for biomass). By contrast, with alternative management across the entire forest, oaks remained dominant even though maples made smaller gains in overall basal area at the expense of other species. Most notably, while alternative management on public lands alone failed to prevent a broad, regional oak decline, alternative management on only private lands succeeded in preserving oak dominance across the landscape – a result that reflects that, although the private land treatment was less intensive, it treated much more land. While alternative public land management’s relative importance increased during the 150-year timeframe as its silvicultural system matured, private forests in the model were always more important than public forests for influencing oak abundance.
While this finding is significant, the authors also note that they made several assumptions. First, they assumed all private landowners would be willing to make major changes to their forest management practices, although research indicates private landowners are often unwilling or unable to bear the “economic burden associated with implementing oak-promoting management” that reduces or eliminates the harvest of valuable oak timber. Second, they assumed an unchanged, early-2000s climate through the year 2160, simplifying the modeling process but omitting climate change, which is a major driver of forest change.
The effects of this omission are hard to gauge. Warming may make some parts of the eastern United States drier, benefiting drought-tolerant oaks, but scientists expect the Northeast to become wetter, favoring mesophilic species such as red maple. All told, the forests of the future may look stranger and more surprising than our models can suggest.