Steve, I live in the middle of a "National Grassland" but it really is TREES! Over the years cedar has invaded and taken over the area. With the Forest Service first you would:
1. Have a "NEPA", National Environmental Protection Act study commissioned and completed saying that there is nothing harmful in your planned action.
2. Have a National Heritage Resource study commissioned and completed saying that there is no relics or such involved.
3. After doing all the above you would then have the Forest Service come out and estimate the height of the trees. You would then pay them by the linear foot.
4. Of course by the time you complete everything the trees will have fallen due to old age!