Just like the vineyards of the Douro valley and the Atlantic forest in Brazil, the cork oak forests are a very special ecosystem, with an extremely delicate balance. They are only found in the Mediterranean basin (Algeria, Morocco), in the southern regions of the Iberian Peninsula under the influence of the Atlantic, like Portugal, which boasts the largest area of cork oaks in the world (730,000 hectares, nearly 33% of the total worldwide). Regarded as national heritage, cork oak forests have been legally protected since long (Decree-law 169/2001). It is forbidden to cut them down and there are incentives to plant and exploit them, an initiative in which Portugal has paved the way and been proved right, since today the use of cork to produce stoppers has become a hugely important industry, with Portugal being the world's leading exporter.

Cork oak forests account for 21% of Portugal's forested area and they supply over 50% of the cork consumed worldwide. Predominantly planted with the Quercus species, the forests also contain extensive areas of holm oak (Quercus Rotundifolia), small groves of Pyrenean oak (Quercus Pyrenaica) and, above all, cork oak (Quercus suber L).

It was only from the 18th century, with the start of the exploitation of cork, that the cork oak began to be viewed with the respect felt for and owed to one of the most traditional trees of Portugal. This was when selective thinning and low density techniques were introduced in the planted area to take advantage of the land for farming. Thanks to these initiatives, at the end of the 19th century the Portuguese cork oaks were regarded as the best treated in the world.