Timber management practices conducted on Duke Forest are designed to provide a diverse set of ecological and economic benefits. These include the establishment and maintenance of demonstration/research areas and the protection of other resource features. Current annual harvesting levels are approximately 1000 MBF (thousand board feet) of pine and 180 MBF of mixed hardwood timber. Revenue generated through the sale of forest products is used to support Forest operations and staff.
Timber on the Duke Forest consists of a mosaic of pine and hardwood cover types and mixed pine-hardwood stands of various species. Past land use practices, including cultivation, pastureland and woodlots (which have been subjected to grazing and timber cutting), form the context from which today’s forest has developed. Areas of the Forest having soils suitable for tilling were generally cultivated prior to Duke’s ownership.
Cultivated fields and pastureland once comprised about two-thirds of the landscape, and these areas now commonly support pine plantations and natural pine stands originating from land abandonment in the the early 1900s through the 1930s. Mixed oak and hickory forests generally occupy the drier upland sites, with yellow poplar, sweetgum, and sycamore on the more moist areas. Lands with steep slopes or rocky soils were generally not tilled, though forests there may have been subjected to open grazing and timber cutting.
Management of the Forest’s timber stands was begun by Dr. Clarence Korstian, the Forest’s first director. Dr. Korstian’s early management activities included planting many of the abandoned fields, allowing natural regeneration in some areas, and planning for a wide range of silvicultural treatments. These management treatments have provided a diverse cross section of stand types which exist on a variety of soils and topographic conditions. Today, as in the past, timber management is undertaken to:
- provide for specific research opportunities,
- provide for an age-class distribution of forest stands from 1 year to more than 250 years of age,
- promote healthy, vigorous tree growth, which reduces risk of insect and disease damage, and
- provide demonstrations of a broad range of forest management practices for class laboratory exercises and research.
A wide array of management or silvicultural practices appropriate for southern forests are undertaken on the Duke Forest. These practices serve to provide stand and habitat diversity, research opportunities, and class and laboratory exercise demonstration areas. Practices may include prescribed burning, disking, pre-commercial and commercial thinning, various regeneration and harvest systems, planting, herbicide application, and fertilization.
Types of harvesting may be grouped into the following categories:
- Thinning: the removal of a percentage of trees within a stand to reduce crowding, promoting vigorous growth and reducing the risk of insect and disease problems. Products removed during thinning include pulpwood, chip-n-saw (material producing both paper chips and lumber), and small diameter sawtimber.
- Improvement Cutting: removal of low quality, poorly formed, diseased trees, or undesirable species, depending on the management of objectives of the particular stand. Products from this activity are both pine and hardwood pulpwood and low quality sawtimber.
- Salvage Cutting: logging of dead and windthrown trees to recover a portion of their value and to reduce the risk of fire or insect damage. All products (including pulpwood, chip-n-saw, and sawtimber) may be removed in these operations. Southern pine beetle infestations and tornado and hurricane damage have been the primary causes of the need for salvage cutting on the Duke Forest.
- Final Harvests: conducted to provide for regeneration of a new stand of trees. This activity may include methods to provide for natural regeneration such as seed tree, shelterwood, or group selection cuts. Each of these methods relies on either natural seeding, advance reproduction or stump sprouts (coppice). Alternatively, cutting may be followed by site preparation and planting. Products removed during final harvests in mature stands are large and small diameter sawtimber and pulpwood from smaller trees and tops of larger ones.