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The flora of Madagascar is exceptionally unique and biodiverse, with more than 80 percent of the island's 14,883 plant species found nowhere else in the world. The prehistoric breakup of the supercontinent Gondwana separated the Madagascar-Antarctica-India landmass from the Africa-South America landmass around 135 million years ago. Madagascar later split from India about 88 million years ago, allowing plants and animals on the island to evolve in relative isolation. This distinctive ecology has led some ecologists to refer to Madagascar as the "eighth continent",〔Hillstrom & Collier Hillstrom (2003), p. 50〕 and the island has been classified by Conservation International as a biodiversity hotspot. Much of the island was originally forested, but nearly all this forest cover has been lost due to increasing global temperatures and human deforestation. The largest remaining stretch of old growth rain forest lies along the eastern coast of the island. The western and southern sides of the island, which lie in the rain shadow of the central highlands, are home to dry deciduous forests, spiny forests, and deserts and xeric shrublands. Due to their lower population densities, Madagascar's dry deciduous forests have been better preserved than the eastern rain forests or the original woodlands of the central plateau. Five plant families are endemic to Madagascar. There are several endemic families including the Asteropeiaceae, Sarcolaenaceae and Sphaerosepalaceae. The humid eastern part of the island was formerly covered in rainforest with many palms, ferns and bamboo, although much of this forest has been reduced by human activity. The west has areas of dry deciduous forest with many lianas and with tamarind and baobabs among the dominant trees. Subhumid forest once covered much of the central plateau but grassland is now the dominant vegetation type there. The family ''Didiereaceae'', composed of four genera and 11 species, is limited to the spiny forests of southwestern Madagascar. Four-fifths of the world's ''Pachypodium'' species are endemic to the island. Three-fourths〔 of Madagascar's 860〔 orchid species are found here alone, as are six of the world's eight baobab species. The island is home to around 170 palm species, three times as many as on all of mainland Africa; 165 of them are endemic.〔Bradt (2011), p. 38〕 Many native plant species are used as herbal remedies for a variety of afflictions. The drugs vinblastine and vincristine, used to treat Hodgkin's disease, leukemia and other cancers, were derived from the Madagascar periwinkle. The traveler's palm, known locally as ''ravinala''〔Ellis (1859), p. 302〕 and endemic to the eastern rain forests, is highly iconic of Madagascar and is featured in the national emblem as well as the Air Madagascar logo. Habitat destruction threatens many of Madagascar's endemic species and has driven others to extinction. In 2003 Ravalomanana announced the Durban Vision, an initiative to more than triple the island's protected natural areas to over or 10 percent of Madagascar's land surface. As of 2011, areas protected by the state included five Strict Nature Reserves (''Réserves Naturelles Intégrales''), 21 Wildlife Reserves (''Réserves Spéciales'') and 21 National Parks (''Parcs Nationaux''). In 2007 six of the national parks were declared a joint World Heritage Site under the name Rainforests of the Atsinanana. These parks are Marojejy, Masoala, Ranomafana, Zahamena, Andohahela and Andringitra. Local timber merchants are harvesting scarce species of rosewood trees from protected rainforests within Marojejy National Park and exporting the wood to China for the production of luxury furniture and musical instruments. To raise public awareness of Madagascar's environmental challenges, the Wildlife Conservation Society opened an exhibit entitled "''Madagascar!''" in June 2008 at the Bronx Zoo in New York. ==See also== * Wildlife of Madagascar * Ecoregions of Madagascar * Deforestation in Madagascar * Illegal logging in Madagascar * Agroecology in Madagascar 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「Flora of Madagascar」の詳細全文を読む スポンサード リンク
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