Richard Hilton, president of Friends of Sand Mountain, said the closure was "kind of pushed on us" but probably the best deal his group of off-roaders could hope for.

"It was one of those things where we felt like any time an environmental group sues, off-road users usually lose," he said.

"They've done a study and there seems to be a good abundance of butterflies out there, but just because of the nature of things, if somebody says they are going to try to list it, we have to compromise some way."

Karen Schambach of Public Employees for Environmental Responsibility, another plaintiff in the lawsuit, said she was encouraged by the closure order because BLM has been slow to respond and was "ignoring its own data that shows habitat for this species has been decimated by recreational excesses."

Some conservationists said there still will be too much intrusion and that more protection is warranted.

"The real test of the bureau's commitment to protecting butterfly habitat will be enforcement," Schambach said.

Ed Waldheim, president of the California Off Road Vehicle Association, said off-roaders would be wise to follow the rules.

"Otherwise the next step is closing. This is something that we have learned the hard way in other areas," Waldheim said.

Violators will be subject to up to one year in prison, but Struble said the initial emphasis will be on distributing maps and educating visitors.

"We want this to work because if it doesn't, it raises the specter of more draconian measures to close it down," he said.

In all, the Sand Mountain Recreation Area encompassing the main dunes consists of about 7.5 square miles of public land. The new order closes all but about a one-square-mile area.

"We are trying to work it to have the habitat, protect the species out there and have recreation out there, too," Struble said. "We need people's help and we weren't getting it under the volunteer system we had the first two years."