The scenery of southeastern Utah is hard to miss. Steep redrock canyons plunge into long and lazy riverbends; wind-sculpted stone arches glow pinkly at sunset. But when biologist Jayne Belnap hikes through this famous landscape, it’s not the show-stopping rocks that draw her attention. It’s the algae.
"This is not a rocky landscape, this is a cyanobacteria landscape — it’s covered with life," she says. These landlocked colonies of blue-green algae, she says, are the "skin" of desert soils and many other surfaces of the planet.
Belnap, a researcher with the U.S. Geological Survey, has studied the soils of the Colorado Plateau for the better part of two decades. She is perhaps the world’s only specialist in biological soil crusts, the living communities of lichens, mosses, and yes, algae that form dark, textured soil surfaces in deserts around the world.
These humble crusts, sometimes known as cryptogamic or cryptobiotic crusts, efficiently "fix" nitrogen, converting extraordinary amounts of atmospheric nitrogen into a form easily used by plants. Studies by Belnap and others show that the crusts’ structure also slows wind and water erosion, forming a web of microscopic roots that holds the soil in place.
But although biological soil crusts are remarkably resistant to harsh conditions, Belnap has found that they can be destroyed in an instant by a wayward boot, hoof or tire. Though such discoveries have made land-management agencies more mindful of soil crusts, Belnap’s beloved microflora are far from safe.
The daughter of a prospector, Belnap grew up in Salt Lake City and spent vacations wandering the backcountry of the Great Basin and Colorado Plateau. "I spent my childhood smashing (crusts)," she laughs, "and my dad spent his adulthood running over them with his bulldozer. I didn’t know any better, and he didn’t know any better." She studied marine biology at college in California, then completed a masters’ degree in community ecology, always preferring to study the workings of ecosystems rather than individual species.
In the early 1980s, she moved to Moab and landed a job as a seasonal botanist in Canyonlands National Park. She didn’t think much about soil crusts until a professor at Brigham Young University, Kimball Harper, invited her to check out some of his study plots near Grand Junction, Colo. Harper had measured greater water runoff and erosion in grazed watersheds than ungrazed watersheds, and he thought the difference was due to the soil-grasping crusts. Though biologists had studied the composition of crusts, Harper was the first to take a serious look at their role in the ecosystem.
Belnap, impressed by the potential importance of the crusts, says she got "pulled down into the dirt." Harper became her Ph.D. advisor, and by 1988, she was a full-time soil-crust researcher for the Park Service. She investigated the nitrogen-fixing abilities of the crusts, then moved on to studies of the crusts’ substantial resistance to wind erosion.
By the late 1980s, Belnap and her coworkers had found that crusts were extremely vulnerable to crushing, and very slow to recover from human and livestock disturbance. Though cyanobacteria return to a disturbed area in a matter of months, the researchers estimated that the mosses and lichens — the most effective nitrogen fixers — do not return to full strength for 250 years or even more.
The Park Service reacted quickly to this news. These days, visitors to national parks in the region are routinely and emphatically warned not to "bust the crust," and it’s common to see hikers weaving carefully through the desert: "They look like they’re drunk," jokes Walt Dabney, who served as the superintendent of Canyonlands and Arches national parks from 1991 to 1999. What’s more, federal land-management agencies usually consider effects on biological soil crusts in their environmental analyses of proposed Colorado Plateau projects.
Despite the substantial impact of Belnap’s data, the long-term prognosis for soil crusts is not good. Though the Park Service keeps a close eye on its visitors, the Bureau of Land Management land that surrounds Moab hosts tens of thousands of much more loosely regulated hikers, mountain bikers, and off-road vehicle enthusiasts every year. Grazing continues in the low-lying areas favored by soil crusts, and the Bush administration has helped fuel a renewed push for oil and gas drilling in the deserts of southeastern Utah (see story next page).
Though Belnap is forceful and fearless in her arguments for the ecological importance of soil crusts, she says such highly political land-management wrangles need nuanced solutions. For instance, while grazing at low elevations almost certainly takes a major toll on crusts, grazing at higher elevations might not have such heavy impacts.
She also says that good management decisions require a wide-ranging and open debate. "Science is only a part of the discussion," she says. "There are cultural voices, economic voices, there are these other voices as well, and they need to be listened to."
"But the one powerful thing science can do is that it can tell you about the true bottom line," she adds. "And the true bottom line is that if you use up the resources that your economics and culture are based on, you’re going to have to move."
Belnap and what she calls her "herd" of seasonal and permanent co-workers recently shifted their shop from the Park Service to the biological research arm of USGS, a switch that has allowed Belnap to participate in soil-crust research in Australia, Africa and even Iceland. She’s currently studying the effect of crusts on water erosion and exotic plant invasions, and looking at the effect of climate change on crust recovery.
She also remains convinced that the dark shadows on the desert are the true — and fragile — foundation of the Colorado Plateau. "Whenever we pull on the thread of what makes the system tick," she says, "we end up with soil crusts on the other end."
The author is contributing editor for HCN.