Driving around southern Portugal in the province of Alentejo, the land is sparsely populated and full of cork trees.

In the 17th century Dom Pérignon was the first to use cork in glass bottles for sealing wine.

Two-thirds of the world’s cork comes from these fields.

It takes 40 years for a cork tree to to grow bark thick enough for harvest. Its useful life lasts another 150-200 years, harvesting the bark every 9 years.

Farmers write the year of the last harvest on each tree, so they can quickly scour the countryside for any ripe bark.