I gather that the author is talking to the West Wind. "Make me thy lyre, even as the forest is" means "Make me your lyre, just as the forest is your lyre". " is an exclamation comparing the author to the forest (fancifully).
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NL8881) Does "Make me thy lyre, even as the forest is:What if my leaves are falling like its own!" mean "make me your lyre, or even make me your forest, whose leaves are falling"?No.