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Habitat degradation : ウィキペディア英語版 | Habitat destruction Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity is mainly for the purpose of harvesting natural resources for industry production and urbanization. Clearing habitats for agriculture is the principal cause of habitat destruction. Other important causes of habitat destruction include mining, logging, trawling and urban sprawl. Habitat destruction is currently ranked as the primary cause of species extinction worldwide.〔Pimm & Raven, 2000, pp. 843-845〕 It is a process of natural environmental change that may be caused by habitat fragmentation, geological processes, climate change〔 or by human activities such as the introduction of invasive species, ecosystem nutrient depletion, and other human activities mentioned below. The terms habitat loss and habitat reduction are also used in a wider sense, including loss of habitat from other factors, such as water and noise pollution. ==Impacts on organisms== In the simplest term, when a habitat is destroyed, the plants, animals, and other organisms that occupied the habitat have a reduced carrying capacity so that populations decline and extinction becomes more likely.〔Scholes & Biggs, 2004〕 Perhaps the greatest threat to organisms and biodiversity is the process of habitat loss.〔Barbault & Sastrapradja, 1995〕 Temple (1986) found that 82% of endangered bird species were significantly threatened by habitat loss. Endemic organisms with limited ranges are most affected by habitat destruction, mainly because these organisms are not found anywhere else within the world and thus, have less chance of recovering. Many endemic organisms have very specific requirements for their survival that can only be found within a certain ecosystem, resulting in their extinction. Extinction may take place very long after the destruction of habitat, however, a phenomenon known as extinction debt. Habitat destruction can also decrease the range of certain organism populations. This can result in the reduction of genetic diversity and perhaps the production of infertile youths, as these organisms would have a higher possibility of mating with related organisms within their population, or different species. One of the most famous examples is the impact upon China's Giant Panda, once found across the nation. Now it's only found in fragmented and isolated regions in the south-west of the country, as a result of widespread deforestation in the 20th Century.〔(The Panda's Forest: Biodiversity Loss )〕
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「Habitat destruction」の詳細全文を読む
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