No restrictions. If it's not owned by .gov, it is private property - no restriction. The laws that created the NF system essentially mapped out areas that could be purchased by the .gov. In practice, the federal gov't rarely had the cash to buy up all the land inside the designated areas, so they end up with a patchwork of parcels bought up from willing sellers. the Sam is very patchwork around the edges. Private property never bought up by the govt is still private property to be traded at will by private citizens.