The cork tree, Quercus suber, is a relatively young species of oak and is unusual in that its bark is so thick and resistant that it can be stripped from the trunk and large branches without hurting the tree.
It grows in sandy soils free of chalk and prefers annual rainfalls between 400 and 800 mm (15–30 in), temperatures which never fall below −5 °C/23 °F, and an elevation between 100 and 300 m (330–1,000 ft). This effectively restricts cork oaks to the coast of the western Mediterranean, particularly Spain, North Africa, and much of Portugal, where cork plays a significant role in the economy. The cork industry was born in Cataluña but was disrupted by the Spanish Civil War. The commercial stability of Algeria, which still grows more than 10% of the world’s cork (though much less than Morocco), was called into question in the 1960s, so that, in the early 21st century, Portugal is the centre of the world’s cork business and cork is an important contributor to the Portuguese economy. Portugal’s cork forests, centred on the Alentejo, are today the most extensive, their 716,000 ha/1.77 million acres representing about 34% of the world’s cork trees, significantly assisted in the late 1980s by eu grants.