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Shelterwood cutting removes part of the old forest stand to allow for a natural establishment of seedlings under the cover of the remaining trees. [1] Initial cuttings give just enough light to allow for the regeneration of desired species. Subsequent cuttings give the new seedlings more light and fully pass the growing space to the new generation. [2] [3] Shelterwood systems have many variations and can be adapted to site conditions and the goals of the landowner. [4] There are concerns associated with this silvicultural system due to windthrow and high costs as well as advantages due to improved aesthetics and cost savings from natural regeneration. [1] [3]
Preparatory cutting thins the stand removing species that are not desired so that they do not contribute seeds to the establishment cut. This also allows the remaining trees to grow faster and produce more seed. If the stand does not have many undesired species the preparatory cut is not necessary. [2] This cut is also not needed if thinning has been implemented throughout the life of the stand, treatment which has the added benefit of building resilience to windthrow. [5]
Establishment cuttings removes enough trees to allow sufficient light into the stand for the desired regeneration while avoiding providing enough to encourage the growth of undesired vegetation. [2] This added light also allows the remaining trees to increase their growth rates and seed production. [3] It is done in a year when seed production is good. Only the best trees are left to seed the regeneration. In many cases the mineral soil is intentionally exposed by equipment allowing small-seeded species that require exposed soil to grow. [2] [6] Sometimes, the cut is followed by the use of herbicides or prescribed fire to suppress any undesired vegetation. [2] Further, in some cases, trees are planted after the cut to increase species diversity, introduced improved stock, or create denser regrowth. [4]
Removal cutting removes all of the mature trees that were left to seed the regeneration. [2] This is to give more light to the established seedlings, allowing them to grow freely. [3] Without this cutting, seedlings will stagnate as the crowns of the older trees grow. [7] This unintentionally damages some of the regeneration which is sometimes desirable as it helps to thin the regrowth, increasing the growth rates of remaining trees. [2] [8] All the mature trees may be removed, or some may be left as reserves. [4] These will continue to grow and may be harvested several decades later, or may be left to die of old age and contribute ecological values to the site. [9] When a very shade-tolerant species is being regenerated this is the only cut needed. [4]
Group shelterwood organizes cutting into concentric circles originating from the first cuts in the patch in the center of the circle. [3] Eventually these concentric circles meet at which point the entire stand has been cut. [5] Sometimes the first cut will simply release a patch of advanced regeneration that will serve as the center of the circle. [2] Usually a third cut is not implemented in these systems since the trees on the sides of the cuts provide shade and a seed source. [4] This has the advantage of eliminating the need to mark trees for removal as the entire overstory is removed in the second cut. [10] It also eliminates the risk of damage to the regeneration from logging equipment. [11]
Strip shelterwood systems organize cuts into narrow strips. [3] The main advantage of this variation is that it provides protection from blowdown. [5] Cutting is conducted into the direction of the prevailing winds resulting in mature trees always being protected by younger trees from wind damage. In other situations the cuts are oriented to maximize or minimize exposure to sunlight to promote regeneration of the desired species [3] Similarly to in group shelterwoods, when the strips are narrow enough, a total overstory removal during the second cut will often be conducted eliminating the need for a third cut. [5]
Irregular shelterwood systems retain the trees left during the establishment cut for an extended period of time resulting in an uneven-aged stand with trees of multiple ages. [11] It maybe done to get additional growth on the oldest trees to get extra-large diameters for wood. [9] It also enhances the scenery, is important for some organisms, and creates old-growth characteristics. [12] [11] The irregular shelterwood system can be further divided into three variants:
Shelterwood is very similar to seed-tree as a regeneration method since both use natural regeneration to create an even aged stand. However, the seed-tree method retains fewer trees since it does not intentionally use tree cover to shelter the regrowth. [2] [13]
Shelterwood cutting is ideal for species that are long-lived, have seedlings that would naturally tend to start under partial shade or full shade, [11] and have seeds that are not easily dispersible. [3] [2] It allows for natural regeneration from site-adapted trees that are retained because of their good genetics. Further, it has improved aesthetics compared to clearcutting since tree cover is always present on the site. [3] There are, however, several particular problems associated with shelterwood systems. Since multiple rounds of cutting are required and since care must be taken to avoid damaging trees being retained costs can be higher than in other systems. Another issue is that trees left during the establishment and preparatory cuts become vulnerable to wind damage. [1]
Coppicing is the traditional method in woodland management of cutting down a tree to a stump, which in many species encourages new shoots to grow from the stump or roots, thus ultimately regrowing the tree. A forest or grove that has been subject to coppicing is called a copse or coppice, in which young tree stems are repeatedly cut down to near ground level. The resulting living stumps are called stools. New growth emerges, and after a number of years, the coppiced trees are harvested, and the cycle begins anew. Pollarding is a similar process carried out at a higher level on the tree in order to prevent grazing animals from eating new shoots. Daisugi, is a similar Japanese technique.
Thinning is a term used in agricultural sciences to mean the removal of some plants, or parts of plants, to make room for the growth of others. Selective removal of parts of a plant such as branches, buds, or roots is typically known as pruning.
Silviculture is the practice of controlling the growth, composition/structure, as well as quality of forests to meet values and needs, specifically timber production.
Clearcutting, clearfelling or clearcut logging is a forestry/logging practice in which most or all trees in an area are uniformly cut down. Along with shelterwood and seed tree harvests, it is used by foresters to create certain types of forest ecosystems and to promote select species that require an abundance of sunlight or grow in large, even-age stands. Logging companies and forest-worker unions in some countries support the practice for scientific, safety and economic reasons, while detractors consider it a form of deforestation that destroys natural habitats and contributes to climate change. Environmentalists, traditional owners, local residents and others have regularly campaigned against clearcutting, including through the use of blockades and nonviolent direct action.
Selection cutting, also known as selection system, is the silvicultural practice of harvesting trees in a way that moves a forest stand towards an uneven-aged or all-aged condition, or 'structure'. Using stocking models derived from the study of old growth forests, selection cutting, also known as 'selection system', or 'selection silviculture', manages the establishment, continued growth and final harvest of multiple age classes of trees within a stand. A closely related approach to forest management is Continuous Cover Forestry (CCF), which makes use of selection systems to achieve a permanently irregular stand structure.
Management of Pacific Northwest riparian forests is necessary because many of these forests have been dramatically changed from their original makeup. The primary interest in riparian forest and aquatic ecosystems under the Northwest Forest Plan (NWFP) is the need to restore stream habitat for fish populations, particularly anadromous salmonids. Some of these forests have been grazed by cattle or other livestock. The heavy hooves of these animals compact the soil. This compaction does not allow the water to be absorbed into the ground, so the water runs off into the stream carrying topsoil along the way.
Patch cuts are logging cuts too small to be considered clearcuts, and are instead considered a form of selection cut. A typical patch cut might be 2-3 tree lengths. Below a certain size, seedling regeneration advantage shifts from the shade intolerant species favored in clearcuts to the shade tolerant species favored by selection harvests.
The following outline is provided as an overview of and guide to forestry:
Carya glabra, the pignut hickory, is a common, but not abundant species of hickory in the oak-hickory forest association in the Eastern United States and Canada. Other common names are pignut, sweet pignut, coast pignut hickory, smoothbark hickory, swamp hickory, and broom hickory. The pear-shaped nut ripens in September and October, has a sweet maple like smell, and is an important part of the diet of many wild animals. The wood is used for a variety of products, including fuel for home heating. Its leaves turn yellow in the Fall.
Logging in the Sierra Nevada arose from the desire for economic growth throughout California. The California Gold Rush created a high demand for timber in housing construction, mining procedures, and building railroads. In the early days, harvesting of forests were unregulated and within the first 20 years after the gold rush, a third of the timber in the Sierra Nevada was logged. Concern for the forests rose and created a movement towards conservation at the turn of the 19th century, leading to the creation of state and national parks and forest reserves, bringing forest land under regulation. Between 1900 and 1940, agencies like the U.S. Forest Service and National Park Service regulated the use of the Sierra Nevada's resources. The economy boom after World War II dramatically increased timber production in the Sierras using clear-cutting as the dominant form of logging. In addition, the California Forest Practice Act, or the Z'Berg-Nejedly Forest Practice Act was enacted in 1973 to regulate private timberland holdings.
Carya aquatica, the bitter pecan or water hickory, is a large tree, that can grow over 30 metres (98 ft) tall of the Juglandaceae or walnut family. In the American South it is a dominant plant species found on clay flats and backwater areas near streams and rivers. The species reproduces aggressively both by seed and sprouts from roots and from stumps of cut trees. Water hickory is a major component of wetland forests now in the south eastern US, because of the selective cutting of more desirable tree species for the lumber industry. It is considered important in cleansing drainage waters since the plants slow water flow during flooding, allowing sediments to fall out of the water column. This tree species is tolerant of wet soils but grows best on well draining soils near rivers and other water ways.
Variable retention is a relatively new silvicultural system that retains forest structural elements for at least one rotation in order to preserve environmental values associated with structurally complex forests.
A veteran tree is one that has ancient features but not the great age of an ancient tree, and is a tree of great cultural, landscape, or biodiversity value due to its ecological and habitat features.
Assisted natural regeneration (ANR) is the human protection and preservation of natural tree seedlings in forested areas. Seedlings are, in particular, protected from undergrowth and extremely flammable plants such as Imperata grass. Though there is no formal definition or methodology, the overall goal of ANR is to create and improve forest productivity. It typically involves the reduction or removal of barriers to natural regeneration such as soil degradation, competition with weeds, grasses or other vegetation, and protection against disturbances, which can all interfere with growth. In addition to protection efforts, new trees are planted when needed or wanted. With ANR, forests grow faster than they would naturally, resulting in a significant contribution to carbon sequestration efforts. It also serves as a cheaper alternative to reforestation due to decreased nursery needs.
Even-aged timber management is a group of forest management practices employed to achieve a nearly coeval cohort group of forest trees. The practice of even-aged management is often pursued to minimize costs to loggers. In some cases, the practices of even aged timber management are frequently implicated in biodiversity loss and other ecological damage. Even-aged timber management can also be beneficial to restoring natural native species succession.
Geneva State Forest is an Alabama state forest in Geneva County, Alabama in the United States. The forest is 7,120 acres (2,880 ha) and sits at an elevation of 210 feet (64 m). It is Alabama's largest state forest. According to the Alabama Forestry Commission the primary objective of the state forest is to provide timber for the lumber industry and the secondary objectives are to provide habitats for wildlife and recreational opportunities for people. The forest is open for year-round recreation including hunting, fishing, hiking and camping.
Gap dynamics refers to the pattern of plant growth that occurs following the creation of a forest gap, a local area of natural disturbance that results in an opening in the canopy of a forest. Gap dynamics are a typical characteristic of both temperate and tropical forests and have a wide variety of causes and effects on forest life.
"Cleaning" and "weeding" are two similar terms referring to the practice of selecting particularly desirable trees in a young stand and removing or killing trees that threaten their survival or development.
Liberation cutting has similar goals to cleaning, namely the allocation of resources to the most promising trees available on a site. What separates liberation cutting from cleaning is that the overtopping competitors are of a distinctly older age class. Need for liberation cutting often occurs when seedlings of a desired species have been regenerated by a logging operation, but that operation has left older, poor quality or undesired trees that are shading the regeneration and limiting its growth.
Continuous cover forestry is an approach to the sustainable management of forests whereby forest stands are maintained in a permanently irregular structure, which is created and sustained through the selection and harvesting of individual trees. The term "continuous cover forestry" does not equate exactly to any one particular silvicultural system, but is typified by selection systems. For example, coppice with standards and Reiniger's target diameter harvesting are also continuous cover forestry. Different existing forest stands may require different silvicultural interventions to achieve a continuously productive irregular structure. Crucially, clearcutting and other rotational forest management systems are avoided.