Beautiful, I really like the way the foliage gets lighter higher up; gives a sense of perspective.
Nice atmospheric change from fore -> background! I do think you could do with filling in the gaps between the leaves (Or at least AAing 'em ;) )
Natural colours, accurate trees and foggy dawn (or sunset?) sky. Nice. Reminds me of the Koraci Wilds, in the game Dragon Age Origins, you know... Amazing.
Interesting mood. Digging it.