The story of change in the Great Basin is written on the landscape. The tectonic forces that shaped the land can be seen in the twisted layers of rock that rise abruptly from the vast flat valleys. Bathtub rings on the hills above shrinking terminal lakes remind us that water was once abundant here.
The region was cooler and wetter when humans first ventured into the Great Basin 10,000 years ago. As the weather grew hotter and drier with the end of the Ice Age, the valleys turned arid and the mountain ranges became "isolated islands of moist montane habitat in a sea of desert," in the words of ecologist Paul Ehrlich of Stanford University. Unique communities of plants and animals survived on each range. Streams and springs in the deserts in between became the last refuges for fish found only here.
Life is precarious in this setting. Nevada is one of the top 10 states for both biological diversity and vulnerability, with close to 300 "sensitive" animals and plants either candidates for listing or already on federal or state lists of endangered and threatened species.
The towering Toiyabe mountain range in the dead center of Nevada is one of the most thoroughly studied "islands' in the Great Basin. Last summer, Adina Merenlender led two dozen "census takers' into the range to count birds, butterflies, and aquatic invertebrates, insects and snails. Merenlender and her colleagues mapped patterns of rarity and diversity as well as disturbances, such as grazing, mining, roads and trails.
Their findings will lay the foundation for a "biological integrity index," a kind of health report for Great Basin ecosystems that will become part of an annual checkup in new forest and range management plans. "We're trying to help set the standards for ecosystem management," says Merenlender.
The ultimate goal, she says, is restoration of healthy ecosystems. But defining restoration is not easy. "We no longer have a plot of land to say: This is what it was like," Merenlender says.
Some of the best-kept ecological sanctuaries in the region survive behind the fences that enclose military bases. One of the few high mountain meadows in the Great Basin that has not been heavily grazed in recent decades is on Mount Grant above the Hawthorne Army Ammunition Depot in western Nevada, according to The Nature Conservancy. And pristine sand dunes can be seen on the Army's Dugway Proving Ground in Utah's West Desert.
"Most species that will be able to persist at all in Nevada will have to coexist with people and human activities," says Peter Brussard, director of the Nevada Biodiversity Initiative. The initiative and the U.S. Forest Service funded Merenlender's biological census taking.
Brussard believes the initiative can help Nevadans see that "we have a biological heritage as valuable as our cultural heritage." But to impart that vision, the project must survive the political heat, he says. "Some people don't want to know."