At times the desert can make people seem small and inconsequential and even foolish. Bill Schlesinger feels that way today. With spikes and tape measure, he and co-worker Jane Raikes have staked out some 100 square yards of desert land in the Jornada Basin, 15 miles north of Las Cruces, New Mexico. Their claim includes some low-slung olive-drab creosote bushes, a clump of wispy tan snakeweed, and a lot of bare soil. Some ants roam the ground. A palm-size Texas horned lizard tries to stay cool in the shade of a creosote. It is a patch of desert that looks pretty much like countless other patches of desert in North America.
Why anyone--even someone like Schlesinger, a biogeochemist from Duke University in North Carolina--should bother to mark and study this particular patch of desert is hard for an outsider to divine. Schlesinger is aware of this. So, as he calls out pairs of numbers to Raikes, he is not surprised by the puzzled looks he gets from passing weekend horseback riders. Raikes goes to the corresponding coordinates in the plot, armed with a rock hammer and a metal pipe. She drives the pipe two inches into the ground, the blows ringing out in the silence. Then she pries the pipe out and taps the clogged soil into a Ziploc bag. I can see it in the press now, says Schlesinger. ‘They banged a pipe in the dirt many times and found it exciting.’
Despite his habitual self-mockery, Schlesinger knows that the tablespoons of soil he and Raikes are collecting may help reveal a profound secret of the desert. If Raikes and Schlesinger had come to this spot 150 years ago, they would have been surrounded by almost uninterrupted grasslands stretching across the basin. Somehow the Jornada has since changed, and Schlesinger, Raikes, and the other researchers who work here think they know why. In many cases, they believe, a desert is like a living organism. Like a cactus or a sidewinder, it needs parents to give it birth, but once kicked into the world it can grow and thrive on its own. Deserts aren’t necessarily the product of outside forces like decreasing rainfall, they say. Rather, it’s the internal ecology of the desert itself--its web of plants, animals, and soil--that drives its growth to maturity and stability. Nor does the transformation of a grassland to a desert necessarily mean the creation of a place where life is more scarce--only one where life is rearranged.
Grasslands are changing into full-blown deserts not only in the Jornada Basin but around the world, on every continent but Antarctica--on every continent, that is, where humans have settled. In North America alone an estimated 1.1 billion acres have been desertified, and researchers suggest that global warming may generate more desert acreage in the coming century. Desertification is sufficiently serious a threat that representatives of 87 countries have drafted a treaty to combat it; only two other environmental crises--ozone destruction and global warming--have earned such attention. But scientists still argue about exactly how desertification happens, how much of it is a matter of natural fluctuations, and how much is man-made. The political impact of the debate is huge--witness the conflict between ranchers and Interior Secretary Bruce Babbitt over grazing rights on public land. If the model Schlesinger and his colleagues at the Jornada have built proves true, it will inject some desperately needed science into this debate.
There’s a touch of ecological hubris in trying to generalize to the entire globe from the Jornada’s 310 square miles, but then, the Jornada is an exceptional place. It is arguably the best-studied desert in the world. As Kris Havstad, the director of the U.S. Department of Agriculture’s Jornada Experimental Range, drives around on a tour of the basin with Schlesinger and Raikes, he recounts the Jornada’s long history: As early as 1600, Spanish wagons were traveling from Mexico City to Santa Fe with livestock. They tried to avoid the Rio Grande because the terrain was broken and heavy and they’d get bogged down. So they crossed over the mountains, up into the plains. The problem is, there’s almost no water here. You read the journals people kept of their trip, and when they get here, they get really quiet.
