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Rainforests are forests characterized by high rainfall, with annual rainfall between .〔(''The Tropical Rain Forest.'' ) Marietta College. Marietta, Ohio. Retrieved 14 August 2013.〕 There are two types of rainforest: tropical rainforest and temperate rainforest. The monsoon trough, alternatively known as the intertropical convergence zone, plays a significant role in creating the climatic conditions necessary for the Earth's tropical rainforests. Around 40% to 75% of all biotic species are indigenous to the rainforests.〔(【引用サイトリンク】 Rainforests.net – Variables and Math )〕 It has been estimated that there may be many millions of species of plants, insects and microorganisms still undiscovered in tropical rainforests. Tropical rainforests have been called the "jewels of the Earth" and the "world's largest pharmacy", because over one quarter of natural medicines have been discovered there. Rainforests are also responsible for 28% of the world's oxygen turnover, sometimes misnamed oxygen production, processing it through photosynthesis from carbon dioxide and consuming it through respiration. The undergrowth in some areas of a rainforest can be restricted by poor penetration of sunlight to ground level. If the leaf canopy is destroyed or thinned, the ground beneath is soon colonized by a dense, tangled growth of vines, shrubs and small trees, called a jungle. The term ''jungle'' is also sometimes applied to tropical rainforests generally. ==Tropical== (詳細はequator. Mean monthly temperatures exceed during all months of the year.〔Susan Woodward. (Tropical broadleaf Evergreen Forest: The rainforest. ) Retrieved on 2008-03-14.〕 Average annual rainfall is no less than and can exceed although it typically lies between and .〔Newman, Arnold. The Tropical Rainforest : A World Survey of Our Most Valuable Endangered Habitat : With a Blueprint for Its Survival. New York: Checkmark, 2002. Print.〕 Many of the world's tropical forests are associated with the location of the monsoon trough, also known as the intertropical convergence zone.〔Hobgood (2008). (Global Pattern of Surface Pressure and Wind. ) Ohio State University. Retrieved on 2009-03-08.〕 The broader category of tropical moist forests are located in the equatorial zone between the Tropic of Cancer and Tropic of Capricorn. Tropical rainforests exist in Southeast Asia (from Myanmar (Burma) to the Philippines, Malaysia, Indonesia, Papua New Guinea, Sri Lanka, Sub-Saharan Africa from Cameroon to the Congo (Congo Rainforest), South America (e.g. the Amazon Rainforest), Central America (e.g. Bosawás, southern Yucatán Peninsula-El Peten-Belize-Calakmul), and on many of the Pacific Islands (such as Hawaii). Tropical forests have been called the "Earth's lungs", although it is now known that rainforests contribute little net oxygen addition to the atmosphere through photosynthesis.〔Broeker, Wallace S. (2006). "Breathing easy: Et tu, O2." Columbia University (Columbia.edu )〕〔Moran, E.F., ("Deforestation and Land Use in the Brazilian Amazon," ) Human Ecology, Vol 21, No. 1, 1993"〕 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「rainforest」の詳細全文を読む スポンサード リンク
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