Shelley is trying to invoke the wind to do as he asks. He asks at the end of each stanza to hear him. He wants the wind to sweep him off "as a wave, a leaf, a cloud!" He needs inspiration. So the wind is a metaphor here to give him creativity.
The wind is thought of as both a "destroyer and preserver." Although it can destroy--like it would in large storms, it can help him to express himself. He wants the wind to play him like he's an instrument, just like it strums through the tree's leaves. He and his generation view nature as beauty and inspiration. Nature is powerful and important, and Shelley wishes to express that in this poem.
The symbols can be found throughout. The leaves are the dead or uninspired left behind. The spring represents renewal, and the wind is the catalyst that gets the seasons to change.