TFC/ED are looking at the collidable tree issue, but it could be a catastrophic frame rate hit, even using a bubble system over forests. There are many millions of trees in DSC.
Nevertheless, in real life, a surprise stinger coming out of a heavily wooded area is a realistic threat. A stinger (MANPAD) would place himself in a clearing in a forest that had a reasonable field of view. Admittedly, he might wait a long time in the hope that a target would fly overhead!
Conversely, if an attack helicopter knew that a forest was in enemy territory, it would be prudent not to fly over it at a height within MANPAD range.