I have the same problem, I've done a simple Devon style course but would prefer to lay a different style that gives more than a few inches of hedge. The young woodland I have could certainly do with the brash rotting down as the ground is still very much field soil rather than a woodland habitat in many places. I just like to wander about the woodland and large amounts of brash doesn't help. I am tempted to burn some, or rather try and make some charcoal/biochar but that would be done in a pit as a kiln would be too expensive and hard to transport. Plenty will still be left for habitat.