You're going for something musical here, and I agree that the meter arrangement is very effective and really pleasing---I have a few points of criticism from a formal point of view.
First off, your beginning isn't fluid enough. The first few lines usually set the meter to put the entire poem into perspective, and it's not usually a good idea to have them trod along in a compromised double-stress like "tall trees."
My advice, noting the importance that the trees are in fact tall (I was going to suggest just saying "the trees," but that's lazy), is to give yourself a more soft opening until the meter is established, and then once it's set for the poem, allow yourself to make subtle alterations such as that one. Add a couple of lines to the start.
I got the impression you were going for an iambic dimeter here... (bimeter? duometer? that's how seldom I use it, I don't even know what it's called). It does have an unfortunately frantic impact on the imagery---it sort of bounces from one concept to the next unless it's sort of slowed down. This is why I don't discourage the metrical variations at all. I think they're needed to keep the flow of the poem in check, so it doesn't end up in fast-forward.
I love how you wrote the closing line:
From swards to skies.
Making the reader sound out the uncommon word, which starts with a double consonant sound, allows them to slow down just enough to breathe in the full impact of that last line.
Oh, and no period after "Rejoice." I realize you're moving on to a new subject matter, and want to use the "and." Maybe put in a semicolon?
I've got to respect your ability to manipulate form to the advantage of your poem. Kudos---
Oh! I almost forgot about the content. Well, I'll give that a go too---
Tall tree's leaves sing
Stirred by wind's wing
Are you talking about The Aeolian Harp here? Very nice (though subtle) reference, although again, not a good point to start on---it might be distracting for people who catch it.
I wonder if there are intended double-meanings in words like "tear" and "fowl?" It all depends how brilliantly you crafted it, eh? If so, I wonder what impact you were going for with that? Subtle notes of discomfort and uneasiness in the midst of all the lovely rabble?
Nice work either way---I appreciate the note on the implicit truth of song in the designed universe.