Alentejo, a rural region in south-central Portugal, and one of the world’s largest sources of cork oaks. All told, Portugal produces about 75% of the world’s cork, and about 75% of this goes into wine bottle stoppers. About 33% of all cork trees grow in Portugal, and 95% of these are in the Alentejo region. A cork oak has two layers of bark—the cork, which is the outer layer, and the inner bark. After the cork has grown to sufficient thickness, you can strip it by hand using an ax with a curved blade. To date, no mechanical harvesting method has been developed, and it requires skill and experience to harvest cork without damaging the tree. Workers must be able to gauge the cork sheet’s thickness, and not cut too deeply into the tree, or they will cause irreversible damage. Done properly though, cork is a renewable resource, and a healthy tree will produce cork almost indefinitely, or until its life expectancy of 600 years is up.
Cork can first be harvested at about 25 years