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Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from ''Quercus suber'' (the Cork Oak), which is endemic to southwest Europe and northwest Africa. Cork is composed of suberin, a hydrophobic substance and, because of its impermeable, buoyant, elastic, and fire retardant properties, it is used in a variety of products, the most common of which is wine stoppers. The montado landscape of Portugal produces approximately half of cork harvested annually worldwide, with Corticeira Amorim being the leading company in the industry.〔J. L. CALHEIROS E MENESES, President, Junta Nacional da Cortiça, Portugal. ("The cork industry in Portugal" )〕 Cork was examined microscopically by Robert Hooke, which led to his discovery and naming of the cell.〔(【引用サイトリンク】title=Robert Hooke )〕 ==Sources== There are about 2,200,000 hectares of cork forest worldwide; 34% in Portugal and 27% in Spain. Annual production is about 200,000 tons; 49.6% from Portugal, 30.5% from Spain, 5.8% from Morocco, 4.9% from Algeria, 3.5% from Tunisia, 3.1% Italy, and 2.6% from France. Once the trees are about 25 years old the cork is traditionally stripped from the trunks every nine years, with the first two harvests generally producing lower quality cork. The trees live for about 300 years. The cork industry is generally regarded as environmentally friendly.〔Skidmore, Sarah, ''USA Today'' (August 26, 2007). ("Stopper pulled on cork debate" )〕 Cork production is generally considered sustainable because the cork tree is not cut down to obtain cork; only the bark is stripped to harvest the cork. The tree continues to live and grow. The sustainability of production and the easy recycling of cork products and by-products are two of its most distinctive aspects. Cork Oak forests also prevent desertification and are a particular habitat in the Iberian Peninsula and the refuge of various endangered species.〔Henley, Paul, BBC.com (September 18, 2008)("Urging vintners to put a cork in it" )〕 Carbon footprint studies committed by Corticeira Amorim, Oeneo Bouchage of France and the Cork Supply Group of Portugal concluded that cork is the most environmentally friendly wine stopper in comparison to other alternatives. The Corticeira Amorim’s study, in particular ("Analysis of the life cycle of Cork, Aluminum and Plastic Wine Closures"), was developed by PricewaterhouseCoopers, according to ISO 14040.〔PricewaterhouseCoopers/ECOBILAN (October 2008). (Analysis of the life cycle of Cork, Aluminium and Plastic Wine Closures ).〕 Results concluded that, concerning the emission of greenhouse gases, each plastic stopper released 10 times more CO2, whilst an aluminium stopper releases 26 times more CO2 than does a cork stopper. The Cork Oak is unrelated to the "cork trees" (''Phellodendron''), which have corky bark but are not used for cork production. 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「Cork (material)」の詳細全文を読む スポンサード リンク
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