Silviculture is the art and science of controlling the establishment, growth, composition, health, and quality of
forestA forest is an area with a high density of trees. There are many definitions of a forest, based on the various criteria. These plant communities presently cover approximately 9.4% of the Earth's surface in many different regions and function as habitats for organisms, hydrologic flow modulators,...
s to meet diverse needs and values of the many landowners, societies and cultures.
Forest regeneration is the act of renewing tree cover by establishing young trees naturally or artificially, generally promptly after the previous stand or forest has been removed. The method, species, and density are chosen to meet the goal of the landowner.
Silviculture is the art and science of controlling the establishment, growth, composition, health, and quality of
forestA forest is an area with a high density of trees. There are many definitions of a forest, based on the various criteria. These plant communities presently cover approximately 9.4% of the Earth's surface in many different regions and function as habitats for organisms, hydrologic flow modulators,...
s to meet diverse needs and values of the many landowners, societies and cultures.
Regeneration
Forest regeneration is the act of renewing tree cover by establishing young trees naturally or artificially, generally promptly after the previous stand or forest has been removed. The method, species, and density are chosen to meet the goal of the landowner. Forest regeneration includes practices such as changes in tree plant density through human-assisted natural regeneration, enrichment planting, reduced grazing of forested savannas, and changes in tree provenances/genetics or tree species. "Human-assisted natural regeneration" means establishment of a forest age class from natural seeding or sprouting after harvesting through selection cutting, shelter (or seed-tree) harvest, soil preparation, or restricting the size of a clear-cut stand to secure natural regeneration from surrounding trees. "Enrichment planting" means increasing the planting density (i.e., the numbers of plants per hectare) in an already growing forest stand."
Common methods
Silvicultural regeneration methods combine both the harvest of the timber on the stand and re-establishment of the forest. The proper practice of sustainable forestry should mitigate the potential negative impacts, but all harvest methods will have some impacts on the land and residual stand. The practice of sustainable forestry limits the impacts such that the values of the forest are maintained in perpetuity.
There are five different regeneration methods:
- Single-tree selection - The single-tree selection method is an uneven-aged regeneration method most suitable when shade tolerant
In ecology, shade tolerance is a plant's abilities to tolerate low light levels. The term is also used in horticulture and landscaping, although in this context its use is sometimes sloppy, especially with respect to labeling of plants for sale in nurseries....
species regeneration is desired. It is typical for older and diseased trees to be removed, thus thinning the stand and allowing for younger, healthy trees to grow. Single-tree selection can be very difficult to implement in dense or sensitive stands and residual stand damage can occur.
- Group selection - The group selection method is an uneven-aged regeneration method that can be used when mid-tolerant species regeneration is desired. The group selection method can still result in residual stand damage in dense stands, however directional falling can minimize the damage. Additionally, forester
250px|thumb|right|Foresters of [[Southern University of Chile|UACh]] in the [[Valdivian forest]]s of San Pablo de Tregua, [[Panguipulli, Chile|Panguipulli]], Chile...
s can select across the range of diameter classes in the stand and maintain a mosaic of age and diameter classes.
- Clearcut - An even-aged regeneration method that can employ either natural or artificial
Treeplanting is the process of transplanting tree seedlings, generally for forestry, land reclamation, or landscaping purposes. It differs from the transplantation of larger trees in arboriculture, and the lower cost but slower and less reliable distribution of tree seeds.It is a silviculture...
regeneration. Clearcutting can be biologically appropriate with species that typically regenerate from stand replacing fires or other major disturbances, such as lodgepole pineLodgepole Pine is a common tree in western North America. Like all pines, it is evergreen.There are three subspecies, one of them with two varieties. All the four taxa are sometimes treated at the rank of variety....
(Pinus contorta). Alternatively, clearcutting can change the dominating species on a stand with the introduction of non-native and invasive species as was shown at the Blodgett Experimental Forest near Georgetown California. Additionally, clearcutting can prolong slashSlash, or slashings, is a forestry term that refers to coarse and fine woody debris generated during logging operations or through wind, snow or other natural forest disturbances. Slash generated during logging operations may increase fire hazard and some North American States have passed laws...
decomposition, expose soil to erosion, impact visual appeal of a landscape and remove essential wildlife habitat. It is particularly useful in regeneration of tree species such as Douglas-firDouglas-fir is the English name applied in common to evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. There are five species, two in western North America, one in Mexico, and two in eastern Asia...
(Pseudotsuga menziesii) which is shade intolerant.
- Seed-tree
Seed trees are trees left after reproduction cutting to provide seeds for natural regeneration in the seed-tree method. These trees serve as both the gene source for the new crop of regeneration and as a source of timber during future cuttings. Because of its importance, a seed tree should be...
- An even-aged regeneration method that retains widely spaced residual trees in order to provide uniform seed dispersal across a harvested area. In the seed-tree method, 2-12 seed trees per acre (5-30/ha) are left standing in order to regenerate the forest. They will be retained until regeneration has become established at which point they may be removed. It may not always be economically viable or biologically desirable to re-enter the stand to remove the remaining seed trees. Seed-tree cuts can also be viewed as a clearcut with natural regeneration and can also have all of the problems associated with clearcutting. This method is most suited for light-seeded species and those not prone to windthrowIn forestry, windthrow refers to trees uprooted or broken by wind. Breakage of the tree bole instead of uprooting is sometimes called windsnap.- Causes :Windthrow is common in all forested parts of the world that experience storms or high wind speeds...
.
- Shelterwood
Shelterwood cutting is a silvicultural system in which trees are removed in a series of cutsdesigned to achieve a new even-aged stand under the shelter of remaining trees....
- A regeneration method that removes trees in a series of three harvests: 1) Preparatory cut; 2) Establishment cut; and 3) Removal cut. The method's objective is to establish new forest reproduction under the shelter of the retained trees. Unlike the seed-tree method, residual trees alter understoryUnderstory is the term for the area of a forest which grows at the lowest height level below the forest canopy. Plants in the understory consist of a mixture of seedlings and saplings of canopy trees together with understory shrubs and herbs...
environmental conditions (i.e. sunlight, temperature, and moisture) that influence tree seedling growth.
Release treatments
- Weeding: A treatment implemented during a stand's seedling stage which removes or reduces herbaceous or woody shrub competition.
- Cleaning: Release of select saplings from competition by overtopping trees of a comparable age. The treatment favors trees of a desired species and stem quality.
- Liberation Cutting: A treatment that releases tree seedling or saplings by removing older overtopping trees.
Thinning
The goal of
thinningThinning 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.- Forestry :...
is to control the amount and distribution of available growing space. By altering
stand densityIn forestry, stocking , is a quantitative measure of the area occupied by trees, usually measured in terms of well-spaced trees or basal area per hectare, relative to an optimum or desired level of density...
, foresters can influence the growth, quality, and health of residual trees. It also provides an opportunity to capture mortality and cull the commercially less desirable, usually smaller and malformed, trees. Unlike regeneration treatments, thinnings are not intended to establish a new tree crop or create permanent canopy openings.
Common thinning methods:
- Low Thinning (thinning from below or German thinning)
- Crown Thinning (thinning from above or French method)
- Selection Thinning (thinning of dominants or Borggreve method)
- Mechanical Thinning (row thinning or geometric thinning)
- Free Thinning
Ecological thinningThinning, a silvicultural technique used in forest management, is a stand manipulation operation designed to modify tree growth. Where trees are managed under a commercial regime, competition is reduced by removing adjacent stems that exhibit less favourable timber quality potential...
is where the primary aim of forest thinning is to increase growth of selected trees, favoring development of wildlife habitat (such as hollows) rather than focusing on increased timber yields. Ecological thinning can be considered a new approach to landscape restoration for some types of eucalypt forests and woodlands in
AustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the continental mainland , the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans...
.
Pruning
PruningPruning is the process of removing certain above-ground elements from a plant; in landscaping this process usually involves removal of diseased, non-productive, or otherwise unwanted portions from a plant. In nature, certain meteorological conditions such as wind, snow or seawater mist can conduct...
, as a silvicultural practice, refers to the removal of the lower branches of the young trees so clear knot free wood can subsequently grow over the branch stubs. Clear knot-free
lumberLumber or timber is wood that is used in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....
has a higher value. Pruning has been extensively carried out in the
Radiata pinePinus radiata is known in English as Monterey Pine in some parts of the world , and Radiata Pine in others ....
plantations of
New ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous smaller islands, most notably Stewart Island/Rakiura and the Chatham Islands. The indigenous Māori named New Zealand Aotearoa, commonly translated as The Land of the Long White Cloud...
and
ChileChile, officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
, however the development of
Finger jointThe finger joint is made by cutting a set of complementary rectangular cuts in two pieces of wood, which are then glued...
technology in the production of
lumberLumber or timber is wood that is used in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....
and mouldings has led to many forestry companies reconsidering their pruning practices.
See also
- Sustainable forest management
Sustainable forest management is the management of forests according to the principles of sustainable development. Sustainable forest management uses very broad social, economic and environmental goals...
- Forestry
Forestry is the art and science of managing forests, tree plantations, and related natural resources. The main goal of forestry is to create and implement systems that allow forests to continue a sustainable continuation of environmental supplies and services...
- Plantations
- Ecological Thinning
Thinning, a silvicultural technique used in forest management, is a stand manipulation operation designed to modify tree growth. Where trees are managed under a commercial regime, competition is reduced by removing adjacent stems that exhibit less favourable timber quality potential...
- Selection cutting
Selection cutting is the silvicultural practice of harvesting a proportion of the trees in a stand. Selection cutting is the practice of removing mature timber or thinning to improve the timber stand. This system may be used to manage even or uneven-aged stands...
- Hardwood Timber Production
Hardwood timber production is the process of managing stands of deciduous trees to maximize woody output. The production process is not linear because other factors must be considered, including marketable and non-marketable goods, financial benefits, management practices, and the environmental...
- Coppicing
Coppicing is a traditional method of woodland management in which young tree stems are repeatedly cut down to near ground level. In subsequent growth years, many new shoots will emerge, and, after a number of years the coppiced tree, or stool, is ready to be harvested, and the cycle begins again...
- World Forestry Congress (WFC)
- Poplar cultivation in Europe
External links