Silviculture
Encyclopedia
Silviculture is the practice of controlling the establishment, growth, composition, health, and quality of forest
s to meet diverse needs and values. The name comes from the Latin silvi- (forest) + culture (as in growing). The study of forests and woods is termed silvology
.
is to control the amount and distribution of available growing space. By altering stand 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:
Ecological thinning
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 Australia
.
, 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 lumber
has a higher value. Pruning has been extensively carried out in the Radiata pine
plantations of New Zealand
and Chile
, however the development of Finger joint
technology in the production of lumber
and mouldings
has led to many forestry companies reconsidering their pruning practices. "Brashing" is an alternative name for the same process.
Forest
A forest, also referred to as a wood or the woods, is an area with a high density of trees. As with cities, depending where you are in the world, what is considered a forest may vary significantly in size and have various classification according to how and what of the forest is composed...
s to meet diverse needs and values. The name comes from the Latin silvi- (forest) + culture (as in growing). The study of forests and woods is termed silvology
Silvology
Silvology is the study of forests and woods, incoporating both the understanding of natural forest ecosystems and the design of silvicultural systems....
.
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. Following are some common methods:- Single-tree selection - The single-tree selection method is an uneven-aged regeneration method most suitable when shade tolerantShade toleranceIn 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, foresterForester250px|thumb|right|Foresters of [[Southern University of Chile|UACh]] in the [[Valdivian forest]]s of San Pablo de Tregua, ChileA forester is a person who practices forestry, the science, art, and profession of managing forests. Foresters engage in a broad range of activities including timber...
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 artificialTreeplantingTree planting 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 from the lower cost but slower and less reliable distribution of tree seeds.In silviculture the...
regeneration. Clearcutting can be biologically appropriate with species that typically regenerate from stand replacing fires or other major disturbances, such as lodgepole pineLodgepole PineLodgepole Pine, Pinus contorta, also known as Shore Pine, is a common tree in western North America. Like all pines, it is evergreen.-Subspecies:...
(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 (logging)Slash, 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-firDouglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...
(Pseudotsuga menziesii) which is shade intolerant.
- Seed-treeSeedstockSeed 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 windthrowWindthrowIn forestry, windthrow refers to trees uprooted or broken by wind. Breakage of the tree bole instead of uprooting is sometimes called windsnap.- Causes :...
.
- ShelterwoodShelterwood cuttingShelterwood 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 understoryUnderstoryUnderstory 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.
- CoppicingCoppicingCoppicing is a traditional method of woodland management which takes advantage of the fact that many trees make new growth from the stump or roots if cut down. In a coppiced wood, young tree stems are repeatedly cut down to near ground level...
- A regeneration method which depends on the sprouting of cut trees. Most hardwoods, the coast redwood, and certain pines naturally sprout from stumps and can be managed through coppicing. Coppicing is generally used to produce fuelwood, pulpwood, and other products dependent on small trees. In Compound coppicing or coppicing with standards, some trees of the highest quality trees are retained for multiple rotations in order to obtain larger trees for different purposes. A close relative of coppicing is pollardingPollardingPollarding is a pruning system in which the upper branches of a tree are removed, promoting a dense head of foliage and branches. It has been common in Great Britain and Europe since medieval times and is practiced today in urban areas worldwide, primarily to maintain trees at a predetermined...
.
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
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.- Forestry :...
is to control the amount and distribution of available growing space. By altering stand density
Stocking (forestry)
In 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 thinning
Ecological thinning
Ecological Thinning is a silvicultural technique used in forest management that involves cutting trees to improve functions of a forest other than timber production....
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 Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
.
Pruning
PruningPruning
Pruning is a horticultural practice involving the selective removal of parts of a plant, such as branches, buds, or roots. Reasons to prune plants include deadwood removal, shaping , improving or maintaining health, reducing risk from falling branches, preparing nursery specimens for...
, 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 lumber
Lumber
Lumber or timber is wood 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 pine
Monterey Pine
The Monterey Pine, Pinus radiata, family Pinaceae, also known as the Insignis Pine or Radiata Pine is a species of pine native to the Central Coast of California....
plantations of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
and Chile
Chile
Chile ,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 joint
Finger joint
A finger joint or comb joint is a woodworking joint made by cutting a set of complementary rectangular cuts in two pieces of wood, which are then glued...
technology in the production of lumber
Lumber
Lumber or timber is wood in any of its stages from felling through readiness for use as structural material for construction, or wood pulp for paper production....
and mouldings
Molding (decorative)
Molding or moulding is a strip of material with various profiles used to cover transitions between surfaces or for decoration. It is traditionally made from solid milled wood or plaster but may be made from plastic or reformed wood...
has led to many forestry companies reconsidering their pruning practices. "Brashing" is an alternative name for the same process.
See also
- CoppicingCoppicingCoppicing is a traditional method of woodland management which takes advantage of the fact that many trees make new growth from the stump or roots if cut down. In a coppiced wood, young tree stems are repeatedly cut down to near ground level...
- Ecological ThinningEcological thinningEcological Thinning is a silvicultural technique used in forest management that involves cutting trees to improve functions of a forest other than timber production....
- Forest gardeningForest gardeningForest gardening is a food production and agroforestry system based on woodland ecosystems, incorporating fruit and nut trees, shrubs, herbs, vines and perennial vegetables which have yields directly useful to humans...
- ForestryForestryForestry is the interdisciplinary profession embracing the science, art, and craft of creating, managing, using, and conserving forests and associated resources in a sustainable manner to meet desired goals, needs, and values for human benefit. Forestry is practiced in plantations and natural stands...
- Hardwood Timber ProductionHardwood Timber ProductionHardwood 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...
- Live crownLive crownThe live crown is the top part of a tree, the part that has green leaves . The ratio of the size of a tree's live crown to its total height is used in estimating its health and its level of competition with neighboring trees....
- Natural landscapeNatural landscapeA natural landscape is a landscape that is unaffected by human activity. A natural landscape is intact when all living and nonliving elements are free to move and change. The nonliving elements distinguish a natural landscape from a wilderness. A wilderness includes areas within which natural...
- Plantations
- Seed tree
- Selection cuttingSelection cuttingSelection 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 the lessening of older trees to improve the timber stand. This system may be used to manage even or uneven-aged stands...
- SilvologySilvologySilvology is the study of forests and woods, incoporating both the understanding of natural forest ecosystems and the design of silvicultural systems....
- Sustainable forest managementSustainable forest managementSustainable 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...
- World Forestry CongressWorld Forestry CongressThe World Forestry Congress is the largest and most significant gathering of the world's forestry sector and it has been held every six years since 1926 under the auspices of the Food and Agriculture Organization of the United Nations , organized by the government of the host country...