Forests are an important part of our state’s environment and economy. When they are well managed, forests provide clean air and water, homes for wildlife, beautiful scenery, places for recreation and more than 5,000 products we all use every day. When they are not well managed, forests are often unhealthy and unproductive because of overcrowding, disease, insects, and competition for light, water and nutrients. To maintain or improve the health and productivity of a forest and to achieve the landowner’s objectives for the property, foresters use a number of management techniques, including harvesting, prescribed burning and reforestation.
In forest management, trees are harvested for a variety of reasons including improving the health of the forest; controlling the types of trees that grow on the site; attracting certain wildlife species; providing a source of income for the landowner; producing paper, lumber and numerous other forest products; and improving access to the area for hikers, hunters and other recreational users.
Just as there are many reasons for harvesting trees, there are many different harvesting methods. Each method has its benefits, drawbacks and conditions under which it is the most suitable way to harvest trees. No one harvesting method is ideal for all situations.
When trees are crowded together, they are in greater competition for sunlight, nutrients and water. As a result, they tend to be less healthy and to grow less vigorously. To improve the health and productivity of the forest, forest managers may remove a portion of the trees in the early stages (10-15 years) of a growing stand of trees so there is less competition for sunlight, water and nutrients. The forest is ‘thinned’ by taking out a certain percentage of the trees. The remaining trees will grow faster, stronger and larger. The thinning also improves the growth of the forest’s understory such as wildflowers and native weeds by increasing the amount of sunlight that reaches the forest floor. This growth provides more food and cover for animals such as quail and rabbits.
This type of harvest is typically referred to as a “pre-commercial” harvest since the costs associated with the forest management (road maintenance, harvesting, etc.) often equal or outweigh the money earned on the harvested trees for the landowners. These type of harvests result in pulpwood size trees, which are smaller in diameter than trees that would be made into lumber.
Clearcutting removes all the trees in a given area, much like a wildfire, hurricane or other natural disturbance would do. It is used most frequently in pine forests, which require full sunlight to grow, and in hardwood forests with yellow poplar, sweetgum, cherry, maple and other species that require full sunlight.
Clearcuts are an efficient way to convert unhealthy stands to healthy, productive forests because they allow forest managers to control the tree species that grow on the site through natural or artificial regeneration.
While a clearcut removes all canopy cover and is unattractive for a short period of time, it is an effective method for creating habitat for a variety of wildlife species. Animals that eat insects, such as turkeys and quails, and those that eat annual and perennial plants, such as bears and deer, thrive in recently clearcut areas. Many creatures also find shelter from weather and predators in the low growing grasses, bushes and briar thickets that follow this type of harvest. In addition, clearcutting is an important forest management tool because it can be used to create edges – areas where two habitat types or two ages of the same habitat meet. Because edges provide easy access to more than one habitat, they usually have more diverse wildlife communities than large blocks of a single habitat.
A clearcut harvest will produce a mixture of pulpwood and sawtimber products for the forest products industry based on the size of the trees and whether the trees are softwood (pine) or hardwood (maple, oaks, etc.). Loggers sort the trees onto different trucks for their different locations. The smaller diameter trees, typically called pulpwood, will head to a paper mill or energy facility. The larger diameter trees, typically referred to as sawtimber, will be sent to a sawmill. Again, different tree species (whether softwood or hardwood) are sent to specific markets.
In a shelterwood cut, mature trees are removed in two or three harvests over a period of 10 to 15 years. This method allows regeneration of medium to low shade-tolerant species because a “shelter” is left to protect them. Many hardwoods, such as oak, hickory and cherry, can produce and maintain seedlings or sprouts in light shade under a partially cut stand. However, the young trees will not grow and develop fully until the remaining overstory trees are removed.
One benefit to shelterwood harvests is that they provide cover and early successional food sources for wildlife. However, this method of harvest is not recommended for trees with shallow root systems because the remaining trees are more susceptible to wind damage after neighboring trees are removed. Another disadvantage to shelterwood cuts is that they require more roads to be built through the forest, and increase the risk of soil disturbance and damage to the remaining trees during harvesting.
Seed Tree Harvest
In a seed tree harvest, five or more scattered trees per acre are left in the harvested area to provide seeds for a new forest stand. These trees are selected based on their growth rate, form, seeding ability, wind resistance and future marketability.
Wildlife benefit from seed tree harvests in much the same way as they do from a clearcut harvest, except that they also reap the benefits of the seed trees themselves. If left on site indefinitely, seed trees eventually may become snags or downed logs, which are important habitat components for woodpeckers and many other species. Seed trees are also excellent food sources and nesting sites for hawks and other birds.
One disadvantage to seed tree harvests is that the remaining trees are at increased risk of damage from wind, lightening, insect attack and logging of nearby trees. This type harvest may also require the landowner to make future investments in thinning and competition control because of uncontrolled reseeding.
Group Selection Harvest
Group selection is essentially a small-scale clearcut where groups of trees in a given area are harvested over many years so that the entire stand has been cut within 40 to 50 years. This method is used primarily on bottomland hardwood stands to harvest high-quality, top dollar logs. The size of the group cut determines the tree species that are likely to return after the harvest. Openings that are less than one-fourth acre favor shade-tolerant species, and larger openings favor sun-loving species.
Group selection provides ideal pockets of young vegetation for grouse, deer and songbirds. But because it requires intensive management and frequent access to all areas of the property, it can be an expensive forest regeneration method.
Single-Tree Selection Harvest
Single-tree selection removes individual trees that are ready for harvest, of low value or in competition with other trees. With single-tree selection, the forest continuously produces timber and constantly has new seedlings emerging to take the place of harvested trees. Single-tree selection maintains a late succession forest that benefits many wildlife species such as squirrels and turkey.
Single-tree selection harvesting is best in small or confined areas for a variety of reasons. One is that this harvesting method requires more roads. In addition, surrounding trees can be damaged during harvests, and frequent use of logging equipment in a given area may compact the soil. Sun-loving trees, which are an important source of food for wildlife, do not regenerate well with single-tree selection, so forest managers must use mechanical or chemical controls to prevent shade-tolerant species from taking over the site.
Prescribed burning is a forest management practice that benefits certain forests by reducing the amount of leaves, branches and dead trees accumulated on the forest floor that could fuel a wildfire. In addition to helping control the spread of wildfire, removal of this “litter layer” also promotes the growth of new forage and succulent plants, which are important sources of food for many wildlife species including rabbits and deer. And the increase in available insects and seeds following a prescribed fire is good for turkeys and a variety of nongame species.
While improving wildlife habitat, prescribed fire also promotes the health of the forest by controlling the spread of disease and insect infestations, and reducing plant competition for nutrients, water and sunlight.
This management technique is commonly used in Longleaf, Shortleaf and Loblolly pine forests because these trees are naturally resistant to fire. In fact, the Longleaf Pine requires fire for its seeds to germinate.
Trees are a renewable resource. This means that they can be grown, harvested, replanted and harvested again and again in a never-ending cycle to provide clean air and water, habitat for wildlife, beautiful views and thousands of products both today and in the future. The process of growing trees on an area that previously has been harvested or cleared is called reforestation.
The two basic methods of reforestation are natural regeneration and artificial regeneration.
Natural regeneration relies on nature to return an area to forestland after trees are harvested. Through natural regeneration, new trees grow from seeds that are carried by the wind, transported or buried by animals, or that are simply dropped on site by mature trees. In addition to producing seedlings from seeds, hardwood trees regenerate naturally by sprouting new growth from the stumps of cut trees.
Artificial regeneration involves human intervention in sowing seeds or planting seedlings. This method of forest renewal has several advantages over natural regeneration. It provides better control over tree spacing, more control over the species present in the new forest, the opportunity to plant genetically improved seeds or seedlings, and a higher rate of tree survival. Although artificial regeneration is more expensive than natural regeneration, the result is usually a more productive stand in a shorter period of time.
Each stage of succession provides different benefits to a variety of wildlife species. In fact, many species need more than one forest type to meet their needs. Rodents and rabbits prefer early successional forest where there are plenty of grasses and shrubs for food and shelter. Deer also need food found in early succession, but require the denser cover of middle and late succession for shelter and escape from danger. Birds of prey nest in mature forests, but feed on rodents and snakes found in early succession. Other wildlife, such as squirrels, find both their food and shelter in mature trees.