Paul S. Johnson

Linking the ecology of natural oak regeneration to silviculture

The regeneration requirements of oaks (Quercus spp.) differ among species. Oaks differ in their ability to produce seed, germinate and, as for reproduction, to endure shade, drought, and other stresses. Under the low to moderate shade that characterizes the understories of their natural habitats, the xerophytic oaks depend heavily on their drought tolerance and capacity to die back and resprout repeatedly. Successful regeneration of xerophytic oaks depends largely on the long-term survival and accumulation of oak reproduction, which may span 2 or more decades. Some of this reproduction develops large roots in advance of final harvest, which thereby enhances long-term survival and the potential for rapid shoot growth after overstory removal. In the more nutrient- and moisture-rich ecosystems, seedling populations of indigenous oaks arising from a single cohort typically fall to near extinction within a few years. High mortality rates are related to seedling intolerance to shade and the prevailing low light intensities under the high stand densities and stratified canopies typical of those ecosystems. In the absence of natural disturbance or silvicultural intervention, oak reproduction beneath dense stands in rich ecosystems typically fails to accumulate over time and thus fails to form the large root systems necessary for competitive success after overstory removal. The required timing and intensity of silvicultural operations for regenerating oaks therefore depend on the ecosystem-specific population dynamics of each species. Knowledge of birth, death, and other population processes of oak reproduction within defined classes of ecosystems, as well as knowledge of periodicity in seed production are prerequisites to the development of ecologically sound silvicultural prescriptions and realistic predictive models for regenerating oaks.

Planting red oak under oak/yellow-poplar shelterwoods: a provisional prescription.

Presents a prescription for planting northern red oak on sites dominated by yellow-poplar using the shelterwood method.