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Clearcutting, clearfelling, or clearcut logging is a forestry/logging practice in which most or all trees in an area are uniformly cut down. Clearcutting, along with shelterwood and seed tree harvests, 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. Detractors see clearcutting as synonymous with deforestation, destroying natural habitats〔U.S. Environmental Protection Agency, Washington, DC (1992). ("Clear cut." ) ''Terms of Environment: Glossary, Abbreviations and Acronyms.'' p. 6. Document no. EPA-175-B-92-001. Accessed 2011-10-12.〕 and contributing to climate change.〔Center for Biological Diversity, Tucson, AZ. ("Clearcutting and Climate Change." ) Accessed 2011-10-12.〕 Clearcutting is the most popular and economically profitable method of logging. However, clearcutting also imposes other externalities in the form of detrimental side effects such as loss of topsoil; the value of these costs is intensely debated by economic, environmental, and other interests. Aside from the purpose of harvesting wood, clearcutting is also used to create land for farming.〔(Global Environmental Governance Project: Forests )〕 The "insatiable human demand for wood and arable land" through clearcutting and other activities has led to the loss of over half of the world's rainforests.〔(Rain Forest Threats ). Retrieved: 2015-01-08.〕 While deforestation of both temperate and tropical rainforests through clearcutting has received considerable media attention in recent years, the other large forests of the world, such as the taiga, or boreal forests, are also under threat of rapid development. The same reasons for preserving the world’s tropical rainforests also apply to the taiga, as do the reasons for destroying them. In Russia, as in North America and Scandinavia, creating protected areas and granting long-term leases to tend and regenerate trees—thus maximizing future harvests—are ways of limiting the harmful effects of clearcutting.〔Kunganavolok (June 25, 1998). ("Taiga! taiga! burning bright." ) ''The Economist''. Retrieved: 2013-08-06.〕 Long-term studies of clearcut forests, such as studies of the Pasoh Rainforest in Malaysia, are also important in providing insights into the preservation of forest resources worldwide.〔Khan, Madeline (February 9, 2004). ("Clear cut forests in Malaysia offer lessons for logging worldwide." ) ''The Varsity'', University of Toronto. Retrieved: 2013-08-06.〕 ==Types== Many variations of clearcutting exist; the most common professional practices are: *''Standard (uniform) clearcut'' – removal of every stem (whether commercially viable or not), so no canopy remains. *''Patch clearcut'' – removal of all the stems in a limited, predetermined area (patch). *''Strip clearcut'' – removal of all the stems in a row (strip), usually placed perpendicular to the prevailing winds in order to minimize the possibility of windthrow.〔British Columbia Ministry of Forests, Victoria, BC. ("Clearcut System Variations." ) ''Introduction to Silvicultural Systems.'' Based on the published workbook: "Introduction to Silvicultural Systems, second edition (July 1999)." Forest Practices Branch.〕 *''Clearcutting-with-reserves'' – removal of the majority of standing stems save a few reserved for other purposes (for example as snags for wildlife habitat), (often confused with the seed tree method). *''Slash-and-burn'' – the permanent conversion of tropical and subtropicals forests for agricultural purposes. This is most prevalent in tropical and subtropical forests in overpopulated regions in developing and least developed countries. Slash-and-burn entails the removal of all stems in a particular area. This is a form of deforestation, because the land is converted to other uses. Slash and burn techniques are typically used by civilians in search of land for living and agricultural purposes. The forest is first clear cut, and the remaining material is burned. One of the driving forces behind this process is a result of overpopulation and subsequent sprawl. These methods also occur as a result of commercial farming. The lumber is sold for profit, and the land, cleared of all remaining brush and suitable for agricultural development, is sold to farmers.〔 *'' Selective Harvesting'' – Selective harvesting is perhaps the most environmentally friendly method of logging. Unlike the aforementioned techniques, this method is used solely for harvesting wood. Logs are selectively harvested around old-growth trees, whose durability and long interconnectedness with the ecosystem provide unique habitats for plants and animals. This method of deforestation is intended to preserve the ecosystem while still reaping the benefits of timber harvesting. However, selective harvesting can still cause habitat destruction, fragmentation, and microclimate alteration that can harm the remaining trees and ecosystem.〔 Clearcutting contrasts with selective cutting, such as high grading, in which only commercially valuable trees are harvested, leaving all others. This practice can reduce the genetic viability of the forest over time, resulting in poorer or less vigorous offspring in the stand. Clearcutting also differs from a coppicing system, by allowing revegetation by seedlings. Additionally, destructive forms of forest management are commonly referred to as 'clearcutting'. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「clearcutting」の詳細全文を読む スポンサード リンク
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