The Bush administration canceled yesterday a two-year ban on new mining claims in roughly 1.2 million acres in and around southern Oregon’s Siskiyou National Forest. The ban was imposed by the Clinton administration in response to lobbying efforts by conservationists, who wanted the area declared a national monument. Instead, former Interior Secretary Bruce Babbitt imposed the moratorium to allow time for further study and public comment. But the Bush administration, a pal to mining interests and no friend to new national monuments, lifted the ban, which was set to expire in January 2003. In its place, the Bureau of Land Management and the U.S. Forest Service proposed a prohibition on new mining claims on 117,000 acres of land — a 90-percent reduction in the amount of land under protection. Critics said the shift threatened key plant and animal habitat.