Public and private landowners use a variety of forestry management practices. Below is a brief look at a few techniques and their benefits:
Natural regeneration relies on nature to return an area to forest land after trees are harvested. Through natural regeneration, new trees grow from seeds that are carried by the wind, transported or buried by animals, or 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 disease-resistant 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.
- Improving the health of the forest
- Controlling the types of trees that grow on the site
- Attracting certain wildlife species
- Producing paper, lumber and numerous other forest products
- 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, 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 to 15 years) of a growing stand 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 and become stronger and larger. The thinning also improves the growth of the forest’s understory, such as wildflowers and native plants, 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.
Clearcutting removes all the trees in a given area, much like a wildfire or other natural disturbance would do. It is used most frequently in pine, oak and aspen forests, which require full sunlight to grow.
While a clear-cut removes all canopy cover and is unattractive for a short time, it is effective for creating habitat for a variety of wildlife species. Animals such as ruffed grouse, hare, rabbits and deer are attracted to the food sources provided by clear-cut 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, clear-cutting 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.
In a shelterwood cut, mature trees are removed in two or three harvests over 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.
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 clear-cut 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 a variety of birds.
One disadvantage to seed tree harvests is that the remaining trees are at increased risk of damage from wind, lightning and insect attack. This type of 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 clear-cut 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. The size of the group cut determines the tree species that are likely to return after the harvest. Openings that are less than a quarter of an 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 for the more shade-tolerant tree species such as sugar maple. Sun-loving trees, which are an important source of food for wildlife, do not regenerate well with single-tree selection. The forest stands may be harvested every 10–20 years so there is more frequent activity.