[at-l] Treeline in Vermont?

[Jan Leitschuh]

Can any of you sages explain why treeline up north occurs at lower elevations, say, 4000 in Vermont?

Is this just an eastern phenomenon, or is it the same in the very northern Rockies too?

Can you point me to an online source that explains this? I kind of know why, but would have a hard time explaining in words.
Please cc me if you respond, as I'm on digest.

Thank ye kindly,
ResearchShoe