Within 3 years of the acquisition of 50 percent of the land authorized for acquisition under section 546a–4 of this title, the Secretary shall develop an amendment to the land and resources management plan for the Hiawatha National Forest which will direct management of the scenic area. Such an amendment shall conform to the provisions of sections 546 to 546a–5 of this title. Nothing in sections 546 to 546a–5 of this title shall require the Secretary to revise the land and resource management plan for the Hiawatha National Forest pursuant to section 1604 of this title. In developing a plan for management of the scenic area, the Secretary shall address the following special management considerations: