Ending 40 years of negotiations, President Clinton signed a bill yesterday that will have the federal government pay $101 million to acquire the Baca Ranch in northern New Mexico, a 95,000-acre site rich in wildlife. The area, which some call “the Yellowstone of the Southwest,” contains the 14-mile-wide collapsed crater of an ancient volcano and provides habitat for one of the country’s largest wild elk herds, as well as 17 threatened or endangered species. The land will now become the Valles Caldera National Preserve, with bipartisan backing from the state’s congressional delegation. Cattle grazing and hunting will still be allowed on the land. The New Mexico environmental group Forest Guardians had been pushing for the area to be made a national park, where such activities would have been prohibited.