Ranchers say their property has been invaded by prairie dogs from Nebraska's Oglala and South Dakota's Buffalo Gap and Fort Pierre national grasslands. Prairie dogs can destroy grazing on private land and federal grasslands that ranchers lease for their cattle.

Don Bright, supervisor of the Nebraska National Forest, developed the plan, which will allow expanded use of a number of lethal and nonlethal methods to keep prairie dogs from spreading to private property.

''I'm pleased that we can now proceed with living up to our commitment to be good neighbors to those who border the national grasslands, and who are concerned about unwanted prairie dog encroachment,'' he said.

The plan will allow more liberal use of zinc phosphide, a rodent poison. Limited prairie dog hunting also will be allowed in South Dakota's Conata Basin area, which has been off-limits to shooting since ferrets were reintroduced in the area more than a decade ago.

Nonlethal management will include an ongoing land-exchange program, and the use of livestock grazing strategies, fencing and land management to encourage growth of taller vegetation that discourages prairie dogs from spreading.

The plan had been appealed by several conservation groups and a coalition of counties and grazing interests but was upheld Monday by Regional Forester Rick Cables of Denver.