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silviculture

 
Dictionary: sil·vi·cul·ture   (sĭl'vĭ-kŭl'chər) pronunciation
n.
The care and cultivation of forest trees; forestry.

[Latin silva, forest + CULTURE.]

silvicultural sil'vi·cul'tur·al adj.
silviculturally sil'vi·cul'tur·al·ly adv.
silviculturist sil'vi·cul'tur·ist n.

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Sci-Tech Encyclopedia: Silviculture
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The theory and practice of controlling the establishment, composition, and growth of stands of trees for any of the goods (including timber, pulp, energy, fruits, and fodder) and benefits (water, wildlife habitat, microclimate amelioration, and carbon sequestration) that they may be called upon to produce. In practicing silviculture, the forester draws upon knowledge of all natural factors that affect trees growing upon a particular site, and guides the development of the vegetation, which is either essentially natural or only slightly domesticated, to best meet the demands of society in general and ownership in particular. Based on the principles of forest ecology and ecosystem management, silviculture is more the imitation of natural processes of forest growth and development than a substitution for them.

The spatial patterns in which old trees are removed and the species that replace them determine the structure and developmental processes of the new stands. If all the trees are replaced at once with a single species, the result is so-called pure stand or monoculture in which all of the trees form a single canopy of foliage that is lifted ever higher as the stand develops. If several species start together from seeds, from small trees already present, or from sprouts, as a single cohort, the different species usually tend to grow at different rates in height. Some are adapted to develop in the shade of their sun-loving neighbors. The result is a stratified mixture. Such stands grow best on soils or in climates, such as in tropical moist forests, where water is not a limiting factor and the vegetation collectively uses most of the photosynthetically active light. If trees are replaced in patches or strips, the result is an uneven-aged stand which may be of one species or many.

These different spatial and temporal patterns of stand structure are created by different methods of reproduction. The simplest is the clear-cutting method, in which virtually all of the vegetation is removed. Although it is sometimes possible to rely on adjacent uncut stands as sources of seed, it is usually necessary to reestablish the new stand by artificial seeding or planting after clear-cutting. The seed tree method differs only in that a limited number of trees are temporarily left on the area to provide seed.

In the shelterwood method, enough trees are left on the cutting area to reduce the degree of exposure significantly and to provide a substantial source of seed. In this method the growth of a major portion of the preexisting crop continues, and the old trees are not entirely removed until the new stand is well established. The three methods just described lead to the creation of essentially even-aged stands.

The choice of methods of regeneration cutting depends on the ecological status of the species and stands desired. Species that characterize the early stages of succession, the so-called pioneers, will endure, and usually require the kind of exposure to sunlight resulting from heavy cutting or, in nature, severe fire, catastrophic windstorms, floods, and landslides. These pioneer species usually grow rapidly in youth but are short-lived and seldom attain large size. The species that attain greatest age and largest size are ordinarily those which are intermediate in successional position and tolerance of shade. Some of them will become established after the severe exposure of clear-cutting, but they often start best with light initial shade such as that created by shelterwood cutting. Their longevity and large size result from the fact that they are naturally adapted to reproduce after disturbances occurring at relatively long intervals. The shade-tolerant species representing late or climax stages in the succession are adapted to reestablish themselves in their own shade. These species represent natural adaptations to the kinds of fatal disturbance caused by insects, disease, and atmospheric agencies rather than to the more complete disturbance caused by fire. See also Ecological succession; Forest ecosystem.

Much silvicultural practice is aimed at the creation and maintenance of pure, even-aged stands of single species. This approach is analogous to that of agriculture and simplifies administration, harvesting, and other operations. The analogy is often carried to the extent of clear-cutting and planting of large tracts with intensive site preparation, especially with species representative of the early or intermediate stages of succession. Mixed stands are more difficult to handle from the operational standpoint but are more resistant to injury from insects, fungi, and other damaging agencies which usually tend to attack single species. They are also more attractive than pure stands and make more complete use of the light, water, and nutrients available on the site. They usually do not develop unless these site factors are comparatively favorable; where soil moisture or some other factor is limiting, it may be possible for only a single well-adapted species to grow. If the site is highly favorable, as in tropical rainforest, river floodplains, or moist ravines, it is so difficult to maintain pure stands that mixed stands are inevitable.

The application of silviculture involves a number of accessory practices other than cutting. In localities of high fire risks, it may be desirable to burn the slash (logging debris) after cutting. Not only does this reduce the potential fuel, but it may also help the establishment of seedlings by baring the mineral soil or reducing the physical barrier represented by the slash. Slash disposal is most often necessary where the cutting has been very heavy or where the climate is so cold or dry that decay is slow. Deliberate prescribed burning of the litter beneath existing stands of fire-resistant species is sometimes carried out even in the absence of cutting to reduce the fuel for wild fires, to kill undesirable understory species, to enhance the production of forage for wild and domestic animals, and to improve seedbed conditions. See also Forest fire.

Integrated schedules of treatment for stands are called silvicultural systems. They cover both intermediate and reproduction treatments but are classified and named in terms of the general method of reproduction cutting contemplated. Such programs are evolved for particular situations and kinds of stands with due regard for all the significant biological and economic considerations involved. These considerations include the desired uses of the land, kinds of products and services sought, prospective costs and returns of the enterprise presented by management of the stand, funds available for long-term investment in stand treatments, harvesting techniques and equipment employed, reduction of losses from damaging agencies, and the natural requirements that must be met in reproducing the stand and fostering its growth. See also Forest and forestry; Forest management.


WordNet: silviculture
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Note: click on a word meaning below to see its connections and related words.

The noun has one meaning:

Meaning #1: the branch of forestry dealing with the development and care of forests


Wikipedia: Silviculture
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Silviculture is the art and science of controlling the establishment, growth, composition, health, and quality of forests to meet diverse needs and values of the many landowners, societies and cultures.

Contents

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." [1]

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 [2] should mitigate the potential negative impacts, but all harvest methods will have some impacts on the land and residual stand.[3] 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:[4]

  • Single-tree selection - The single-tree selection method is an uneven-aged regeneration method most suitable when shade tolerant 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, foresters 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 regeneration. Clearcutting can be biologically appropriate with species that typically regenerate from stand replacing fires or other major disturbances, such as lodgepole pine (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 slash 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-fir (Pseudotsuga menziesii) which is shade intolerant.
  • Seed-tree - 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 windthrow.
  • Shelterwood - 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 understory environmental conditions (i.e. sunlight, temperature, and moisture) that influence tree seedling growth.

Intermediate stand treatments

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 thinning 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:

  • 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 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.

Pruning

Pruning, 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.

See also

Citations

  1. ^ 'Fact Sheet 4.12. Forest Regeneration', IPCC Special Report on Land Use, Land-Use Change And Forestry
  2. ^ Oregon State University Extension Service
  3. ^ RESIDUAL DAMAGE IN A CONIFER STAND THINNED WITH A CTL SYSTEM, University of Idaho
  4. ^ Nyland, R. D. 2002 Silviculture: Concepts and Applications, Second Edition. The McGraw-Hill Companies, Inc. New York. 704 p. ISBN 0-07-366190-2

References

  • Daniel, T. W., J. A. Helms, and F. S. Baker 1979. Principles of Silviculture, 2nd Edition. McGraw-Hill, New York. 521 pp. ISBN 0-07-015297-7
  • Evans, J. 1984. Silviculture of Broadleaved Woodland. Forestry Commission Bulletin 62. HMSO. London. 232 pp. ISBN 0-11-710154-0
  • Hart, C. 1995. Alternative Silvicultural Systems to Clear Cutting in Britain: A Review. Forestry Commission Bulletin 115. HMSO. London. 93 pp. ISBN 0-11-710334-9
  • Nyland, R. D. 1996. Silviculture, Concepts and Applications. The McGraw-Hill Companies, Inc. New York. 633 pp. ISBN 0-07-056999-1
  • Nyland, R. D. 2002 Silviculture: Concepts and Applications, 2nd Edition. The McGraw-Hill Companies, Inc. New York. 704 pp. ISBN 0-07-366190-2
  • Savill, P., Evans, J., Auclair, D., Falck, J. 1997. Plantation Silviculture in Europe. Oxford University Press, Oxford. 297 pp. ISBN 0-19-854909-1
  • Smith, D. M. 1986. The Practice of Silviculture, 8th edition. John Wiley & Sons, Inc., New York. 527 pp. ISBN 0-471-80020-1
  • Smith, D. M., B. C. Larson, M. J. Kelty, P. M. S. Ashton. 1997. The Practice of Silviculture: Applied Forest Ecology, 9th edition. John Wiley & Sons, New York. 560 pp. ISBN 0-471-10941-X
  • Reid, R. (2006) 'Management of Acacia melanoxylon in Plantations' [1]
  • Reid, R. (2002) 'The Principles and Practice of Pruning' [2]

External links


Translations: Silviculture
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Dansk (Danish)
n. - skovbrug, forstvidenskab

Nederlands (Dutch)
bosbouw

Français (French)
n. - sylviculture

Deutsch (German)
n. - Waldbau

Ελληνική (Greek)
n. - δασοκομία

Italiano (Italian)
silvicoltura

Português (Portuguese)
n. - silvicultura (f)

Русский (Russian)
лесоводство

Español (Spanish)
n. - silvicultura

Svenska (Swedish)
n. - skogsodling, skogsskötsel

中文(简体)(Chinese (Simplified))
造林术, 森林学

中文(繁體)(Chinese (Traditional))
n. - 造林術, 森林學

한국어 (Korean)
n. - 삼림 육성, 식림법, 임학

日本語 (Japanese)
n. - 林学, 植林法

العربيه (Arabic)
‏(الاسم) فرع من علم ألحراجه يعنى بزراعه ألغابات وألعنايه بها‏

עברית (Hebrew)
n. - ‮גידול עצים כענף של יערנות‬


 
 

 

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Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.  Read more
Sci-Tech Encyclopedia. McGraw-Hill Encyclopedia of Science and Technology. Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.  Read more
WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Silviculture" Read more
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