((a)) ** Severability** If any provision of this chapter, or the application of any provision of this chapter to any person or circumstance is held invalid, the application of such provision or circumstance and the remainder of this chapter shall not be affected thereby.

((b)) ** Savings** Nothing in this chapter—

((1)) diminishes or expands the trust responsibility of the United States to Indian tribes, or any legal obligation or remedy resulting from that responsibility;

((2)) alters, abridges, repeals, or affects any valid agreement between the Forest Service and an Indian tribe;

((3)) alters, abridges, diminishes, repeals, or affects any reserved or other right of an Indian tribe; or

((4)) alters, abridges, diminishes, repeals, or affects any other valid existing right relating to National Forest System land or other public land.