And we wasted a lot of our forests on superfluous things like war ships - see the Castillan plateau which is now a dry and barren land.
Once you’ve destroyed an ecosystem, it takes a lot of effort to bring back. Often you can’t just expect to plant the same type of trees as before and expect it to take.
There are ways to introduce things gradually, but it’s not an on/off switch.
Plus there are entire keystone species of trees that blights drove to actual or morphological extinction. I don’t know about European species, but the mountains of appalachia used to be covered in massive American Chestnut trees that were so big around at the trunk they were on par with west coast species. After the blight, you can still find groves of chestnut trees, but its like they’re a different species - they live 7-9 years and die basically around the time they first mast. They never live long enough to really leave the sapling phase.
