The consent of the State of Alabama is hereby given to the United States to acquire by purchase, condemnation or gift, for forest purposes, such lands, within the exterior national forest boundaries or within the watershed or drainage areas of the Tennessee River in Alabama, as have heretofore or may hereafter be approved by the Department of Conservation and Natural Resources and as, in the opinion of the administrative executives of the United States, may be or are needed for the consolidation, extension and administration of national forests. In all condemnation proceedings for the acquisition of lands, the rights of the United States shall be limited to the specific object set by the laws of the United States regarding national forests.