Shelterwood cutting

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A shelterwood establishment cut in an eastern white pine stand in Maine. Shelterwood Demeritt UMaine.jpg
A shelterwood establishment cut in an eastern white pine stand in Maine.

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]

Contents

Cutting stages

Preparatory cut

Forest thinning in Finland. Thinning is similar to and can be implemented instead of preparatory cutting. Thinned forest 2016-06-12.jpg
Forest thinning in Finland. Thinning is similar to and can be implemented instead of preparatory cutting.

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 cut

European beech regeneration following an establishment cut in a German shelterwood system. Brohmer-Berge-Rothemuhl-20-10-2009-34.jpg
European beech regeneration following an establishment cut in a German shelterwood system.

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 cut

A young forest in Romania. Following a removal cut, the now even-aged stand will be composed of young trees like above. Young forest.. - panoramio.jpg
A young forest in Romania. Following a removal cut, the now even-aged stand will be composed of young trees like above.

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]

Variations

Group shelterwood

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

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

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 vs. seed-tree

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]

Advantages & disadvantages

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]

Related Research Articles

<span class="mw-page-title-main">Coppicing</span> Method of woodland management

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.

<span class="mw-page-title-main">Thinning</span> Removal of some plants to improve the growth of other plants

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.

<span class="mw-page-title-main">Clearcutting</span> Forestry/logging practice in which most or all trees in an area are uniformly cut down

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.

<span class="mw-page-title-main">Forest ecology</span> Study of interactions between the biota and environment in forests.

Forest ecology is the scientific study of the interrelated patterns, processes, flora, fauna and ecosystems in forests. The management of forests is known as forestry, silviculture, and forest management. A forest ecosystem is a natural woodland unit consisting of all plants, animals, and micro-organisms in that area functioning together with all of the non-living physical (abiotic) factors of the environment.

<span class="mw-page-title-main">Selection cutting</span> Forestry practice

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:

<i>Carya aquatica</i> Species of tree

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.

<span class="mw-page-title-main">Veteran tree</span> Tree of great value due to its age

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.

<span class="mw-page-title-main">Assisted natural regeneration</span>

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.

<span class="mw-page-title-main">Even-aged timber management</span>

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.

When logging began in British Columbia, Canada, in the late 19th century, the overriding concern was to harvest timber in the most economical fashion. Reforestation, aesthetics and protection of fish and wildlife habitat were not issues of great concern.

<span class="mw-page-title-main">Close to nature forestry</span>

Close to nature forestry is a management approach treating forest as an ecological system (ecosystem) performing multiple functions. It is developing in the peri-alpine coutries of Europe for more than 70 years, based on certain sustainable forest management practices from the late 19th century. Close to nature silviculture tries to achieve the management objectives with minimum necessary human intervention aimed at accelerating the processes that nature would do by itself more slowly. It works with natural populations of trees, ongoing processes and existing structures using cognitive approach, as in the case of so called selection forest or other types of uneven-aged forests. Its theory and practice takes forest as a self regulating ecosystem and manages it as such.

<span class="mw-page-title-main">Gap dynamics</span>

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.

<span class="mw-page-title-main">Cleaning (forestry)</span>

"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.

<span class="mw-page-title-main">Continuous cover forestry</span> Approach to sustainable forest management

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.

References

  1. 1 2 3 Schönenberger, W.; Brang, P. (2004-01-01), Burley, Jeffery (ed.), "SITE-SPECIFIC SILVICULTURE | Silviculture in Mountain Forests", Encyclopedia of Forest Sciences, Oxford: Elsevier, pp. 1085–1094, ISBN   978-0-12-145160-8 , retrieved 2024-02-24
  2. 1 2 3 4 5 6 7 8 9 10 11 Welford, Lana; Williams, Allie (2016). "3.4. Regeneration Methods: Shelterwood". SFA Silviculture. Retrieved 2024-02-24.
  3. 1 2 3 4 5 6 7 8 9 "Module 2: Harvesting Systems | Natural Resources and Renewables | Government of Nova Scotia". Government of Nova Scotia. Retrieved 2024-02-24.
  4. 1 2 3 4 5 "What Is a Silvicultural System?" (PDF). United States Department of Agriculture. December 2016. Retrieved 2024-02-24.
  5. 1 2 3 4 5 "Part 3 - Variations of silvicultural systems". Government of British Columbia. 2024-01-05. Retrieved 2024-03-16.
  6. Wessels, Tom (1997). Reading The Forested Landscape: A Natural History of New England. New York, NY, USA: Countryman Press. p. 119. ISBN   0-88150-420-3.
  7. "Appendix C – Harvest Cutting Methods" (PDF). Ottawa National Forest. 2024-03-10.
  8. Punches, John (September 2004). "Thinning: An important forest management tool". Oregon State University Extension Service. Retrieved 2024-03-12.
  9. 1 2 "Chapter 61 - Big Tree Silviculture" (PDF). Wisconsin Department of Natural Resources. 2007-11-21. Retrieved 2024-03-10.
  10. Bennett, Karen (2018-02-13). "Expanding Gap Shelterwoods: A Flexible System for Regenerating Mid-tolerants". University of New Hampshire Extension. Retrieved 2024-02-24.
  11. 1 2 3 4 5 6 7 Raymond, Patricia; Bédard, Steve; Roy, Vincent; Larouche, Catherine; Tremblay, Stéphane (December 2009). "The Irregular Shelterwood System: Review, Classification, and Potential Application to Forests Affected by Partial Disturbances" (PDF). Journal of Forestry: 405–413.
  12. Kern, Christel C. (Spring 2021). "The Irregular Shelterwood System: What in the World?" (PDF). US Forest Service. Retrieved 2024-03-10.
  13. Hummel, S.; O'Hara, K. L. (2008-01-01), Jørgensen, Sven Erik; Fath, Brian D. (eds.), "Forest Management", Encyclopedia of Ecology, Oxford: Academic Press, pp. 1653–1662, ISBN 978-0-08-045405-4, retrieved 2024-02-24