“Nature’s Yard Work”

[Brownlie]

I think this is not so bad. 

From my perch, so high, above the painted land -- We don't necessarily need so high and above, even perch and above is a little redundant.
I gaze upon, far below, dunes of desert sand
Where the sun shone down in juicy, golden rays
And warmed the belly of the earth for long, forgotten days -- Warmed the belly of the earth has a nice sonorous ring to it.  
Now, wind picks up and thrashes ‘bout the tiny grains -- Now, I'm sure this thrashing wind that carries grains could be specified and explained in a new way.
Who, all alone, stand no chance against the drowning rains
Thunder rumbles o’er my fragile, dusted ledge -- I wouldn't use o'er unless you are intentionally trying to be quaint.
And clouds billow ‘cross majestic mountain hedge -- Again 'cross, I'm not sure...
Yet, on my perch, all is for a moment quiet
Though endlessly beneath me, nature shivers in a riot -- Think of the rhyming on consecutive lines here Quiet/Riot. Isn't that the name of a punk band? Though punk music can be cool, it seems to jangly (like a Christmas bauble or something).
Mother rushes, changing ‘round the old landscapes
At last, I flap my wings and make my great escape. --- Your rhyme word, escape, hinders the poem more than it helps it. You demonstrated an act then made it weaker by telling exactly what was going on in an abstraction. (Note, I'm not necessarily providing my own set of hack-axioms, but I'm stating my opinion for this particular case.)

I think this particular piece can be tightened up. Perhaps someone editing it could try to eliminate redundancy first. All of that being said, I might not be the best person to be taking advice from. This is not so bad though.