Same! Digging into this wiki says (with source):

Typically, once it reaches 25 years old, its thick bark can be harvested for cork every 9 to 12 years without causing harm to the tree.[4]

The source is a Rainforest Alliance article from 2024: https://www.rainforest-alliance.org/species/cork-oak/

Cork oak is unique in its ability to regenerate its outer bark. After a tree reaches 25 years of age, it can be stripped of its cork once every 9 to 12 years without causing damage to the tree. A single cork oak, which lives up to 200 years, can be harvested over 16 times.

Cool thing I learned: harvested cork oak stores 5x as much carbon as unharvested. Get that cork!

Depends on the tree species, technically the only living part of a tree trunk is a thin layer of material right under the visible bark. If you go around and expose the wood in a circle around the trunk the tree will die, but I guess if you're careful the bark can be harvested without harming the tree.

Disclaimer: I am not an arborist, this is just my recollectio of an explanation I got several years ago.

I didn't seem like a plantation. We were hiking a trail and kept coming across them. Sometimes one, sometimes a bunch. I think they're scattered throughout the forest and some people have rights to certain areas.