Table 2. Characteristics of even-aged stands and types of wildlife favored.
Managing your forest resources requires an understanding of various forestry systems and their effects on wildlife. When left completely untouched, forests experience natural disturbances such as fires, floods, tornadoes, insects, diseases, and earthquakes. After a tornado, for instance, damaged areas in a forest must begin again with the early stages of succession. Also, insects and diseases cause openings in the forest that allow more sunlight to reach the ground. Forest management practices often simulate these disturbances. We can use these practices to manipulate the forest for maximum productivity.
The goals and objectives outlined in your management plan, along with the characteristics of your property, determine which forest management systems to use. Each system benefits different groups of wildlife, and you can use just one or any combination of systems. The following is a basic introduction to the most common forest management systems.
An even-aged system creates a stand of trees that are all approximately the same age. Usually all the trees in a given area are harvested at one time or in several cuttings over a short time to keep the stand approximately the same in age. This method is especially common in harvesting or managing sun-loving trees like the loblolly pine and some hardwoods like the yellow poplar.
Hardwood stands often appear to be uneven in age because the trees vary in size. It is not uncommon to find an oak 8 inches in diameter growing beside one that is 16 inches in diameter. Although the trees are the same age, the smaller tree may not have grown as rapidly as the larger one because it received less sunlight, nutrients, and water.
Even-aged forests can be managed through three harvesting practices: clearcutting, shelterwood cutting, and seed-tree cutting. These practices can benefit wildlife species that require open, full sunlight including forbs, grasses, and brushy vegetation. (See Table 2.)
Table 2. Characteristics of even-aged stands and types of wildlife favored.
Clearcutting is a method of harvesting and regeneration that removes all trees within a given area. Used most frequently in pine and hardwood forests that require full sunlight for growth, this method simulates a major natural disturbance and creates an early successional habitat.
As a landowner, you should keep in mind that the size of your clearcut affects the livelihood of wildlife. Generally, on most small tracts, no more than 20 acres should be cut in one area to improve habitat. However, on tracts of 500 acres or more of mature timber, larger clearcuts of 50 to 100 acres yield excellent quail habitat and economic returns. Smaller areas of less than 5 acres can be cleared near roads or as firewood and pulpwood cutting areas. These smaller sections add to the diversity of the forest and will attract wildlife year round.
In general, timber harvest areas should have irregularly shaped boundaries to
maximize forest edge. These edges separate mature stands from young,
regenerating stands and meadows, creating a variety of wildlife habitats. For
more information on edges, see
Leave strips of uncut timber at least 100 yards wide to separate clearcuts.
Referred to as buffer or leave strips, these areas provide habitat diversity,
edge, travel lanes, den trees, and hard mast. You can influence wildlife
species that feed, nest, and travel within the buffer by varying the location
and width of the buffer strips. Early successional species such as rabbit,
quail, and deer generally benefit from narrower leave strips, while wild turkey
and squirrels prefer wider strips with more cover and mast from mature hardwood
stands. The width and location of buffer strips along stream and river edges
also can affect fish, reptile, and amphibian populations. Leave all shrubs
along streams to help protect water quality.
Leaving islands of uncut timber within clearcut areas that are linked to the
main forest by strips of mature trees will enhance wildlife habitat by
maintaining mast-producing plants. Connected strips or islands of mature timber help
develop and retain den trees. The best type of island is at least a 1/4-acre clump of
mature, long-lived species of oak such as white, water, chestnut, and red. Try to maintain old
oaks and other hardwoods with visible cavities that can be used by wildlife.
Shelterwood cutting clears trees in two or three cuts over several
years, resulting in a stand of trees that are nearly the same age. This
simulates a moderate natural disturbance. Regeneration of shade-tolerant
species is possible when a "shelter" is left to protect them. Shelterwood
methods provide cover for wildlife as well as early successional food. Some
shade-loving
species, including northern red oak and American beech, are excellent sources
of food for wildlife. In addition to perpetuating timber species that produce
food for wildlife, shelterwood cuts can be used to improve the appearance of
your property.
Remember that shelterwood cutting involves more planning from resource
professionals and higher logging costs than does clearcutting. Also, the chance
for soil and early regeneration disturbance increases with repeated stand
entry.
Seed tree harvesting is commonly used on light-seeded
pine species that produce frequent seed crops. In a seed tree harvest, several
mature trees are left standing to reseed the next stand of trees. In effect, it
is a compromise between clearcutting and shelterwood methods.
The proper selection of seed trees is critical. Foresters should select seed
trees that are well spaced, windfirm, vigorous, sound, and of good form and
quality. Mark trees clearly to avoid accidental removal and damage during the
regeneration cut. The benefits to wildlife are nearly the same as with the
clearcutting system, with the exception of the seed trees. If left
indefinitely, the seed trees eventually can become snags or downed logs that
are important habitat for woodpeckers and many other species. Seed trees are
also excellent food sources and nesting sites for hawks and other birds. For
additional information on seed distribution for particular trees, contact your
county Cooperative Extension Center or your local forester. See also Working
with Wildlife 14, Snags and Downed Logs.
The seed-tree method is low in cost and creates a pleasant appearance. Landowners also enjoy
the second harvest payment when the seed trees are removed after regeneration.
However, seed tree harvests can require some additional investment for
precommercial thinning and competition control.
An uneven-aged system maintains a timber stand in many growth stages, either through cutting
of selected groups of trees or of individual trees. This management method
simulates minor natural disturbances such as windthrows, insect and disease
damage, or spot fires. Succession is held at the mid-to late-successional
stage but never allowed to reach its climax. Uneven-aged
management benefits many wildlife species that need cover for nesting and
brooding as well as early successional foods. (See Table 3.)
Group selection is the process of selecting groups of trees for harvest
over many years until eventually - 40, 50, or more years later - the
entire stand has been cut. In essence, each cut is a small-scale
clearcut in an area of 2 acres or less. Group selection produces high-quality,
veneer-grade hardwoods that bring top dollar when sold. The method is used primarily on
bottomland hardwoods.
Group selection cuts provide ideal pockets of young vegetation for grouse,
woodcock, deer, and songbirds. Note, however, that this practice requires
intensive management and frequent access to all areas of the property. For
these reasons, group selection may be feasible only where high-value
trees exist on accessible sites.
Single-tree selection is the most intensive uneven-aged
practice. Individual trees are cut that are ready for harvest, of low value, or
in competition with the future crop trees. Under this method, the forest
continuously produces timber, with new seedlings constantly emerging to take
the place of harvested trees. Unless single-tree selection removes irregular, low-quality
trees along with merchantable timber, this management system will gradually
reduce the value of the timber on your property.
Single-tree selection holds the stand in a perpetual state of late succession that never
reaches a climax. Many wildlife species benefit from the diversity and cover of
a late-successional forest, including turkey and squirrels. The disadvantage of single-tree
selection is that more frequent harvests require more mechanical disturbances
to the wildlife habitat that you are trying to enhance. Also, sun-loving
tree species that are important for wildlife food will not grow in this system.
Single-tree selection requires frequent harvesting and chemical or mechanical control of
shade-tolerant species that would otherwise naturally dominate the stand over time. Shade-tolerant
species are slower growing and typically command a lower price in most North
Carolina markets.
Part of choosing a forest management system is planning for the future
growth of the stand. Two basic methods of reforestation are natural
regeneration and artificial regeneration.
Natural regeneration, just as the name implies, relies on nature to
provide the seed to start a new stand of trees. If you set the proper
conditions at and before harvest, you can anticipate new, vigorous growth with
little cost. Natural regeneration is most appropriately used with seed tree
cut, shelterwood cut, single-tree
selection, and group selection systems. (See Table 4.)
Artificial regeneration includes seeding and planting. By planting
seedlings you can choose the species, genetic quality, and spacing of your
future stand. Although this process requires a capital investment, the result
is a more productive stand in a shorter period. Artificial regeneration is
commonly used after clearcutting or is used experimentally with oak seedlings
after group selection. (See Table 4.)
Pine plantations and young hardwood stands provide a multitude of wildlife
benefits when properly planned and managed. Also, after you have completed your
timber harvest, you can obtain professional assistance and financial incentives
to start a new stand of trees or improve a young crop of seedlings.
Other information is available in Woodland Owner Note 16, Steps to
Successful Pine Plantings; Woodland Owner Note 9, Reforestation of
Southern Pines, and Bulletin 463, A Guide for Regenerating and Managing
Natural Stands of Southern Hardwoods, available from your county
Cooperative Extension Center.
Return to Table of Contents
Uneven-Aged Management
Table 3. Characteristics of uneven-aged stands and type of wildlife favored.Reforestation
Table 4. Regeneration methods associated with management systems.