Quercus suber

Quercus suber, commonly called the cork oak, is a medium-sized, evergreen oak tree in the section Quercus sect. Cerris. It is the primary source of cork for wine bottle stoppers and other uses, such as cork flooring and as the cores of cricket balls. It is native to southwest Europe and northwest Africa. In the Mediterranean basin the tree is an ancient species with fossil remnants dating back to the Tertiary period. It grows to up to 20 m (66 ft), although it is typically more stunted in its native environment. The leaves are 4 to 7 cm (1.6 to 2.8 in) long, weakly lobed or coarsely toothed, dark green above, paler beneath, with the leaf margins often downcurved. The acorns are 2 to 3 cm (0.79 to 1.18 in) long, in a deep cup fringed with elongated scales. The cork oak forest is one of the major plant communities of the Mediterranean woodlands and forests ecoregion. Natural stands of cork oak can support diverse ecosystems. For example, in parts of northwestern North Africa, some cork oak forests are habitat to the endangered Barbary macaque, Macaca sylvanus, a species whose habitat is fragmented and whose range was prehistorically much wider. In Western Europe, particularly in Portugal and Spain, the cork oak forests are home to endangered species such as the Iberian lynx, the most critically threatened feline in the world. As a pyrophyte, this tree has a thick, insulating bark that makes it well adapted to forest fires. After a fire, many tree species regenerate from seeds (as, for example, the maritime pine) or resprout from the base of the tree (as, for example, the holm oak). The bark of the cork oak allows it to survive fires and then simply regrow branches to fill out the canopy. The quick regeneration of this oak makes it successful in the fire-adapted ecosystems of the Mediterranean biome. The tree forms a thick, rugged bark containing high levels of suberin. Over time the cork cambium layer of bark can develop considerable thickness and can be harvested every 7 to 10 years to produce cork. The harvesting of cork does not harm the tree (though such activity tends to reduce its life expectancy), in fact, no trees are cut down during the harvesting process. Only the bark is extracted, and a new layer of cork regrows, making it a renewable resource. The tree is cultivated in Spain, Portugal, Algeria, Morocco, France, Italy and Tunisia. Cork oaks are considered to be soil builders and their fruits have been shown to have useful insecticidal properties. Cork oak forests cover approximately 25,000 square kilometres in those countries (equivalent to 2,500,000 hectares (6,200,000 acres)). Portugal accounts for around 50% of the world cork harvest. Cork oaks cannot legally be cut down in Portugal, except for forest management felling of old, unproductive trees, and, even in those cases, farmers need special permission from the Ministry of Agriculture. Q. suber is commonly grown in agroforestry systems, known as montado in Portugal and dehesa in Spain. These are open woods with low tree density (50–300 trees/ha). In these systems, forage species are commonly grown under the trees and grazed by cattle during the summer. Cork oaks commonly live more than 200 years. Virgin cork (or 'male' cork) is the first cork cut from generally 25-year-old trees. Another 9 to 12 years is required for the second harvest, and a tree can be harvested about twelve times in its lifetime. Cork harvesting is done entirely without machinery, being dependent solely on human labor. Usually five people are required to harvest the tree's bark, using a small axe. The process requires training due to the skill required to harvest bark without inflicting too much damage to the tree. The European cork industry produces 300,000 tonnes of cork a year, with a value of €1.5 billion and employing 30,000 people. Wine corks represent 15% of cork usage by weight but 66% of revenues.