The Congress declares that the installation of a proper system of transportation to service the National Forest System, as is provided for in sections
532 to
538 of this title, shall be carried forward in time to meet anticipated needs on an economical and environmentally sound basis, and the method chosen for financing the construction and maintenance of the transportation system should be such as to enhance local, regional, and national benefits: Provided, That limitations on the level of obligations for construction of forest roads by timber purchasers shall be established in annual appropriation Acts.