So it occurred to me that from a distance volumes look a lot like trees so I took a stab at it. This test looks a lot more like moss than trees, but I wanted to post the idea for others to try and improve. I still think volumetrics is a majorly under tested and utilized new feature that has a great future.
This a a point density volume texture emitted from the hills with tree trunks as objects assigned to the points. For more info and tutorials I did on how this was done see my thread here:
VolumeTree.blend (642 KB)