Your clouds are pretty good, they could use some smaller 'pieces' that break off to help smooth the transition from grey to black. As a whole the piece is still quite nice, just some odd bits that still could use some work.
Eh, I thought they were treetops.

This is really cool, but I think Adam makes a good point.
I like the moon. It'd be pretty cool if the dragon's wings were kind of encompassing it.