The US chief of the Forest Service announced today that he would decide on logging and road building in a large expanse of the national forest system pending the outcome of legal disputes about the future of forest land. In a directive to his regional forest managers, the chief, Dale N. Bosworth, said he chose to assume decision-making authority because a Clinton administration rule restricting commercial operations in so- called roadless areas was tied up in at least eight lawsuits involving seven states.