Speaking of forgotten woodlands, I've talked about this on HN two times already, might as well say it third time. Go on Google maps and look at the size of the Sherwood forest. I've never truly recovered from that experience.
I mentioned Birnam Wood in another post, which features in MacBeth. Shakespeare plays fast and loose with Scottish history, but Birnam Wood was a real place. One or two of the old trees are still there, but not much. The area has been reforested a bit within the past two hundred years.