In an attempt to preserve the wildness and solitude of eastern Utah's Canyonlands National Park, the National Park Service wants to restrict camping, backpacking and mountain biking in heavily used and ecologically important areas of the park. In a 66-page environmental assessment, the agency lays out five alternatives for managing backcountry use of the 337,000-acre park and the adjacent 75,000 acre Orange Cliffs unit of the Glen Canyon National Recreation Area. The agency's preferred alternative calls for restricting the number of overnight permits granted each month, limiting the number of "vehicle camps' used by mountain bikers along the popular White Rim trail, and restricting access to Jasper Canyon and Virginia Park, two of the park's 14 relict areas that have never been grazed. At recent hearings in Denver and Moab, Utah, off-road vehicle enthusiasts criticized the agency for recommending the closure of 12 miles of road to motorized vehicles, while environmentalists urged it to close more roads. The plan is spurred by a dramatic increase in the number of park visitors. Canyonlands attracted 50,000 visitors in 1980 and 397,000 last year. For a copy of the Environmental Assessment for Backcountry Management Plan, or to send comments due by Feb. 18, contact the National Park Service, Canyonlands National Park, Southeast Utah Group, 125 West 200 South, Moab, UT 84532-2995 (801/259-3911).