The answer, in Gunnison at least, is that no one knows for sure.
"I wish I could say someone has looked at how important ranch lands are from a systems standpoint," says Susan Lohr, an ecologist herself and a founder of the Legacy. "But no one has."
There are good reasons to believe that preserving ranch lands provides important benefits to the surrounding ecosystems. It's a matter of faith and common sense.
Open pastures with willow-lined creeks certainly look better than fields of houses. When homesteaders staked out the private lands in the West, they went for lands with water, rich soils and the ability to grow crops, or at least grass and hay to feed livestock. It seems safe to assume that the most productive lands for people might also be the most productive for other living things.
Much more research is needed, but two seminal studies put the importance of ranch lands into focus.
The first study is by Andrew Hansen, an associate professor of ecology at Montana State University. Hansen and his colleagues studied ranches and ranchettes--parcels of 40 acres or less--around Yellowstone National Park. They found that songbirds from higher-elevation public lands used the private ranch lands as breeding grounds.
Ecologists call these areas "sources" for songbird populations. But the ranchettes are death traps, or "sinks," in the lingo of ecologists. The subdivided lands attracted more magpies and other birds that prey on the songbirds. If the subdivision of ranch lands continues, Hansen speculates that the songbirds will get squeezed between increasing development at lower elevations, and protected but unproductive breeding grounds at higher elevations.
The second study has come to define this issue as much because of the personality and advocacy of the scientist, Rick Knight, as his results. Knight, a professor of wildlife biology at Colorado State University, lives on a ranch and has become a passionate advocate for preserving ranches.
Knight's research put a precise focus on the question at hand: How do the alternatives compare to ranching? He looked at 93 comparable sites on ranches, in wildlife refuges and in subdivisions with about one house per 40 acres. He found that the ranches had at least as many species of birds, carnivores and plants as similar areas that are protected as wildlife refuges, and fewer invasive weeds. More importantly, the ranches provided better habitat for wildlife than the ranchettes, which had fewer native species and more invasive species than either ranches or refuges.
Knight's research is a good first cut at defining the value of ranch lands versus ranchettes. But it needs to be replicated in other places. And studies need to go beyond the generalist species that he looked at, and to consider specific species at risk in specific places--which brings us back to Gunnison.
Despite the recent boom in ranch land conservation in the county, the Gunnison sage grouse, a candidate for the endangered species list, has continued to decline in recent years. The population has dropped 30 percent since 1999 and is now down to 1,800 to 2,400 birds in the Gunnison Basin. Ranchers and environmentalists are still debating whether grazing is a cause of the decline or whether ranch management can be part of the recovery.
The Gunnison County Ranchland Conservation Legacy doesn't usually require any specific protection for the sage grouse in the conservation easements it negotiates with landowners.
"We felt it is enough to get an easement on the ground and keep the landscape intact," says Susan Lohr. "The thousands of acres we've managed to keep together are a lifeline for the grouse."
But sage grouse advocate Clait Braun is skeptical.
"I think conservation easements in general have potential, but it's too early to tell," he says. "The management (of the protected lands) isn't changing. And with present management, the numbers are going down."
Braun says he is afraid that, within a generation, the odds are 50-50 that "you're going to have a conservation easement with no sage grouse."
One Legacy project that does include specific protections and a management plan for sage grouse is the recent deal on the Ochs Ranch, a 4,500-acre project involving seven families. The reason? Money.
Lohr says she would have been satisfied with the usual conservation easement provisions prohibiting development on the Ochs Ranch. "The way ranch lands are managed is very beneficial for grouse," she says. But the Colorado Department of Wildlife provided crucial funding for the deal and, in return, demanded explicit protections for the imperiled bird.