Even out west, most city folk (and most suburban folk, for that matter) don't really know very much about large-scale ranching.

Still, for the most part, we rather like the idea that the cowboys' way of life still goes on out there in the splendid isolation of rural Montana.

But ranchers often aren't just maintaining a particular lifestyle. They're preserving that splendid isolation, too.

The latest to do so in perpetuity is the family that owns the Sieben Live Stock Company. The Hibbards recently donated a 40,064-acre conservation easement on their ranch to the Montana Land Reliance, the biggest easement ever given to the land trust in its 30-year history.

In return for an easement, which involves giving up development rights to land with conservation and open space value, ranchers get substantial tax incentives. In the case of the Hibbard family and many others, the incentives will enable them to pass the working ranch on to a new generation without forcing them to sell part of it off to pay inheritance taxes.

The deal not only lets the family continue ranching -- no small affair involving 1,650 mother cows, 1,400 yearlings and 1,500 sheep -- and carry on a 100-year legacy. It also is clear from Sunday's newspaper story that the Hibbards understand that their property straddling a major wildlife corridor has a significance beyond the family. "It's not just important to us," said Scott Hibbard. "It's important to Montana. It's important to have working landscapes. There are not a lot of old ranching families left."

"It goes to the heart of what is Montana," added Montana Land Reliance Managing Director Rock Ringling. "Is it Gallatin Valley McMansions or is it the historic landscapes and wildlife habitat of Montana?"

There's room in Montana, of course, for a lot of development, McMansions and all. But much of what is special in the state can to be found in the out-of-the-way isolation of its ranches, preserved over the years by a distinctly non-urban lifestyle. Now a conservation easement will preserve both the ranch and its isolation, 40,000 acres worth, for long after the current owners are gone.