Well, that's gonna be another good WIP to watch. Your forests looks already nice, though I would mix a bit more lights&shadows. I mean, there's no particular reason for a forest to be lighter on the edges and darker inside (on a top view). Density and tree-size is generally quite chaotic (except man-organized ones), depending on ground variations and the competition between plants.
Another question : what is the purpose of the (texture?) effect close to the forest that looks more digital?