To me its about the scale. The trees and grasses are huge compared to the mountains and hills. It's always a trade off since you really cann't make it accurate to reality (you don't have too either) you just want to represent the elements accurately. Reduce trees by 50% to see it that works, I got a feeling it might be more like 25% to get close and then it's the detail needed for the trees - look at Max's stuff you has a really nice balance.