The Cheatgrass Problem

Unless U.S. land-use and cattle-grazing policies change radically, tens of millions of acres of western grassland are doomed

ENVIRONMENT

DRIVING THROUGH the Snake River plains of southwestern Idaho, a casual visitor would not realize that the big-sky country fanning out beyond the windshield is desperately ill. Hazy blue mountains on the horizon, a few nearby hills that call attention to the prevailing flatness, and long stretches of treeless sagebrush steppe painted straw-yellow by the dry summer grass: isn’t that how these rangelands should look?

Not quite. And the reason they don’t look right is that they are afflicted by what one authority calls “the most devastating ecological problem in the West.”

The trouble starts with that straw-yellow grass. It’s the weedy, alien annual grass Bromus tectotum, widely known as cheatgrass—also known as downy brome, downy chess, bronco grass, Mormon oats, six-weeks grass, and junegrass. This profusion of common names underscores the scope of the problem. Cheatgrass grows in most states, and is probably the most common plant in the intermountain West, an area roughly four times the size of New England which stretches from the Rockies to the Cascades and Sierras and from the Sonoran Desert to eastern Washington. In the sagebrush grasslands, its preferred habitat, cheat dominates more than 100 million acres. Mike Pellant, a range conservationist with the Idaho office of the Bureau of Land Management (BLM), calls Idaho’s Snake River plains the “cheatgrass capital of the world,” but northern Nevada and northern Utah could dispute his claim. Pellant would no doubt love to lose the title.

Cheat is a thin-stemmed, knee-high grass topped by a spray of bristly awns, the kind that elicit curses when they catch in socks. A native of Eurasia, it arrived in North America in the mid1800s, making its first recorded appearances in wheat fields in Washington, Utah, and British Columbia. Farmers named it cheatgrass because they felt that this pernicious outsider cheated them of their crops. In the following decades cheat seeds were sown across the West as they lodged in the hair of livestock, got mixed in with shipments of wheat seeds, and got dumped along railroad sidings when cattle bedstraw was discarded. By the 1930s cheatgrass had shown up in most of the areas where it is present today. The broad dispersal of cheat would have caused little trouble, however, if ranchers hadn’t inadvertently weakened the range’s natural defenses.

Cheat flourishes amid ruin: even though it found the environment of the sagebrush grasslands agreeable, an undamaged range could have withstood the Eurasian invasion. By the late 1800s, however, most of the native plant communities of the intermountain West had been flagrantly degraded by overgrazing. For several decades cattle and sheep had been swarming over the land; not until many years later would most of this range come under the supervision of the BLM and other government agencies and be managed with a modicum of restraint.

Many native sagebrush-grassland plants are easily damaged by livestock, particularly cattle. They evolved without being subjected to regular, frequent depredations by herds of large herbivores and can’t cope well with the unaccustomed grazing, trampling, and wallowing—whereas cheat evolved under pressure from camels, horses, and other formidable grazers, and can comfortably co-exist with cattle. As long as cheat has time to set seed, which it does quickly and prolifically, it isn’t affected by trampling, for cheat is an annual, and so the adult plant becomes dispensable once it has done its reproductive duty. Cheat can also stand up to repeated grazing, because it often grows back from its ground-level meristem even if cropped short.

Another feature of sagebrush grasslands provides the means by which cheat tends to enter a native plant community. Most native grasses in the intermountain West are bunchgrasses, which grow in distinct clumps with only sparse vegetation between. In an undisturbed community these spaces are covered by a thin layer of lichens, mosses, and other organisms, called the cryptogamic crust. Even light grazing shatters this fragile crust, providing openings for cheat seeds to take root.

Once cheat has established colonies within a native plant community, it reveals its decisive adaptation: it can germinate and grow rapidly. This ability gives cheat a conclusive edge when its seedlings are pitted against native seedlings. Typical is cheat’s interaction with bluebunch wheatgrass, which was the most common grass in most of the sagebrush grasslands before the ascendancy of cheat.

Both cheatgrass and bluebunch wheatgrass seeds usually germinate in the fall. Bluebunch roots grow perhaps six inches, and then growth slows to a near standstill when winter cools the soil at the depth of the seedlings’ root tips to temperatures below 46°-50° Fahrenheit. Cheat roots grow more than half again as fast as bluebunch roots, and they can grow at soil temperatures at least as low as 37°. Because the roots rapidly push down to warmer soil depths, where temperatures rarely drop below 37°, they can keep growing through the winter.

In spring, when soil temperatures rise sufficiently for bluebunch wheatgrass’s roots to resume growing, cheat’s roots are already about three feet long and its secondary roots are often well developed. As the thirsty bluebunch roots move deeper, they encounter al-

most no moisture, because the cheat roots have already taken it. As a consequence, during the dry summers characteristic of the intermountain West, many of these bluebunch wheatgrass plants die from lack of water.

When competing with cheatgrass seedlings, the seedlings of most native plants in the intermountain West meet much the same fate. This doesn’t mean, however, that a few scattered cheat colonies will inexorably expand and take over a native community. Mature, healthy native perennials possess established root systems that can compete successfully with cheat for moisture. Cheat may enter a healthy native community, and even become a permanent resident, without overrunning it—unless further disturbance occurs.

Overgrazing is one such disturbance, and its persistence leads to a steady increase in the density of cheat. Steady, that is, until the cheat population becomes so dense that fires take over.

FIRES HAVE always had an impact on sagebrush grasslands, but before cheat they were infrequent and small. Because bunchgrasses are scattered and the cryptogamic crust doesn’t carry fire, fire doesn’t spread easily in a native plant community. Many native plants stay green well into the summer, which delays the onset of the fire season. No one is sure exactly how often fire hit native communities in precheat days, but a widely cited 1990 study by Steve Whisenant, an ecologist then at Brigham Young University, indicates that historically any given site in the Snake River plains burned at least once every sixty to 110 years.

Cheatgrass, though, grows in dense stands that carry fire with frightening ease. Cheat usually dries out by midJune, some two to four weeks earlier than most of the natives, significantly lengthening the fire season. Its fine growth readily ignites. Once cheatgrass fills in enough of the open spaces in a sagebrush-grassland community, the site is virtually certain to burn soon—as often as every three to five years, according to Whisenant’s study. Bill Casey, the branch chief of fire management for the Boise district of the BLM, notes that typically more acres burn in his district each year than in any other district in the country with the exception of some districts in Alaska.

The speed of cheat fires makes them difficult to contain. The thunderstorms that spark wildfires usually pack strong winds that fan the flames. Everyone in cheat country seems to have a story about an extreme example—like the one I heard from Stephen Monsen, an ecologist with the U.S. Forest Service. One day Monsen was driving through southern Idaho when he caught up to a cheat fire that was blowing parallel to the road. Monsen slowed down to pace the fire, but he didn’t have to slow down much—it was sizzling along at about 40 m.p.h.

What Casey calls “multiple occurrences” also make it difficult to fight cheat fires. Dry thunderstorms rumble along the storm track from Oregon and unleash thousands of lightning bolts into cheat stands throughout the Snake River plains. Often many widely separated fires start within a few hours; at one point in 1986, forty-six fires were burning simultaneously in the Boise district. “It’s a zoo,” Casey says. “We’re absolutely inundated with fire reports.

We have to set priorities because we can handle only three or four good ones at a time.”

After fire strikes a cheat-infested native community, the cheatgrass usually flourishes. In a severe blaze the sagebrush and many other shrubs are killed and the aboveground growth of the herbaceous species, including cheatgrass, is consumed. After the crowns of mature native bunchgrasses burn, their roots wither, and with the mature natives out of the way, the competitive advantages of cheat seedlings enable them to win the recolonization race. One study showed that three years after a burn some 10,000 cheat plants crowded each square meter of the study area, leaving no room or resources for any other plants.

Less-severe fires may spare mature native plants, but if the fire stresses them too much, and especially if subsequent grazing adds to their stress, they become less competitive with cheat. That allows cheat to proliferate, which increases the odds that the site will burn again in the near future. That next burn will either kill the remaining mature native plants or stress them further, aiding the spread of cheat and setting the stage for the next fire. This downward spiral generally continues until cheat dominates the community. Fire begets cheat and cheat begets fire.

By disrupting natural plant succession, the cheat-wildfire cycle allows cheat to maintain a stranglehold on a plant community for decades, perhaps longer. Simultaneously, the fires spread cheat when they intrude into native communities. In an average year in the Boise district two or three decades ago, with cheat already established, sixty to seventy fires burned 25,000 to 30,000 acres. In an average year from 1980 to 1987, after several more turnings of the cheat-wildfire cycle, 115 fires burned 186,000 acres, despite increased suppression efforts. Literally as well as figuratively, the sagebrush grasslands are going up in smoke.

Cheatgrass doesn’t, however, restrict itself to sagebrush grasslands. As an annual, it evolves quickly, and adapted strains are stealing into habitats that cheat originally found inhospitable: wetter, colder areas, where the grass is overwhelming much of the piñonjuniper woodland and even turning up in Ponderosa pine forests at elevations as high as 7,000 feet; and drier, hotter areas, where it is corrupting vast expanses of salt desert.

To make matters worse, a host of alien plants even more pestilential than cheat are spreading through the intermountain West. The most prolific is medusahead wild rye, another weedy, alien annual grass. Medusahead possesses all the bad traits of cheat and some traits that are even worse. Indeed, medusa usually outcompetes cheatgrass, so it’s thriving in the wake of cheat fires. Eventually medusahead may oust cheatgrass as the dominant plant in much of the sagebrush grasslands. Knapweed, musk thistle, skeletonweed, and other alien weeds fully as unsavory as medusahead are also encroaching on the range. The more the land is degraded, the more such plants increase; and the more such plants increase, the more the land is degraded.

In their darker moments scientists speculate that if we don’t pull out of this tailspin, in a hundred years we may be left with a barren landscape of spiked, noxious alien weeds, pocked with rock piles and patches of eroded earth, as has happened elsewhere in the world. Already the cheat-wildfire cycle is exacting a steep ecological price. Soil erosion has accelerated, wildlife habitat has been damaged, and soil fertility has been reduced. Robust communities that used to include dozens of plant species have degenerated into cheat monocultures, and when plant diversity plummets, so does the diversity of the insects, reptiles, birds, and mammals that depend on those plants.

Though ecologists see cheatgrass as an instrument of impoverishment with no redeeming qualities, ranchers tend to view it with ambivalence. Unlike a diverse native community, in which one or another of the plants usually is green and appealing to cattle, cheat monocultures most often present cattle with dry, barbed, almost unpalatable forage. Cheat’s sharp awns can stab livestock and cause lumpy jaw and blindness. But—and this “but” has sapped the livestock industry’s resolve to deal with cheatgrass—for about six to eight weeks each spring cheat provides lush growth that cattle relish.

Bob Baker, an Idaho rancher who runs cattle on cheat-ridden range in the Snake River plains, says that he’d hate to do without cheat’s springtime abundance. He has even used cheat for winter forage. Ideally, he’d have a range of native plants mixed with select alien ones, including cheat. Such variety is “like having meat, potatoes, and vegetables on your plate,” he explains. Increasingly, however, as the cheat-wildfire cycle continues, only cheatgrass is on the plate, and that concerns Baker and other ranchers. The threat of medusahead worries them even more, because it’s virtually unpalatable all the time. Baker bought his own firefighting equipment in order to pounce on any blazes that start on his land—as happens about once a year. “You can lose all your fall and winter forage in an afternoon,” he says.

THE FIRST STEP in dealing with cheatgrass and other alien weeds should be to protect the native plant communities that are still reasonably intact. ‘That means shielding them from further disturbance, so that their natural resistance to cheat isn’t undermined. This might not stop cheat’s expansion, but it would slow it.

The most widely accepted course of action is to suppress the fires and stop them from spreading into native communities—but how to do that is problematic. Firefighting alone will never do more than slightly diminish the rate of cheat’s conquest. More promising are various preventive strategies, among them “greenstripping,” a BLM initiative that has garnered widespread support. A greenstrip is a firebreak planted with vegetation that is resistant both to fire and to intrusion by cheat. Standard firebreaks won’t work, because cheat thrives in the bared earth and soon covers the open space. Range managers hope to reduce the size of wildfires by carving large cheat lands into smaller and smaller tracts. Greenstripping is expensive, however; developing effective plants is difficult; and often, particularly during drought, plantings fail. Even if greenstripping eventually works as hoped, it’s far from a panacea. Mike Pellant, the director of the greenstripping program, says, “Greenstripping will slow a cheat fire, preserve some resources, and reduce fire costs, but it’s still just a stopgap.”

Long-term protection wall come only if anti-wildfire measures are accompanied by a substantial decrease in the amount of disturbance caused by livestock, but so far grazing management has been relatively neglected as a means of protecting intact native communities. Although most scientists strongly recommend reducing and relocating grazing, the relevant government agencies have mixed feelings about the idea, and most ranchers despise it. Ranchers and many agency managers feel wronged when current grazing practices are impugned. They assert that today’s grazing management represents a huge improvement over the anarchy of years past. They’re right. Unfortunately, the improvements haven’t kept pace with the demands generated by the rapidly escalating cheatgrass invasion.

Recent research has yielded much knowledge that could further improve grazing management. For example, livestock are turned out on many allotments in May and June because the conventional wisdom has it that grazing earlier would rob plants of carbohydrates during a critical growth stage. However, new evidence indicates that only small stores of carbohydrates are needed, and that some native plants (in particular bluebunch wheatgrass) are in fact most vulnerable precisely in May and June, so they would be better protected if grazed in March or April (but not when the ground is still wet from the spring thaw, or the trampling will devastate the natives; grazing management is not simple and doesn’t lend itself to rigid, one-dimensional schemes).

Grazing practices also need to be tailored to the nature of a particular site. A hilly allotment shouldn’t be assigned a carrying capacity based solely on the amount of forage it contains, because cattle will avoid the steep slopes and throng the bottomlands, hammering the more accessible areas. So-called suitability criteria are supposed to block this route to overgrazing, but they’re frequently circumvented.

Even some actions that seem ecologically correct must change. For example, managers evaluating a burned winter deer range will rule that the range is ready to be grazed by cattle again if the plants that the deer need are plentiful and prospering. But those plants might be growing on only a third of the site. The remaining two thirds might be dotted with battered bunchgrasses that are just a grazing season or two away from being an easy mark for cheat. Better to keep cattle off until the whole site is healthy enough to resist cheatgrass.

In general, to deal with cheatgrass and its ilk effectively, grazing needs to be managed to combat alien weeds, not to fatten livestock. For example, in determining whether a site that’s being rested is ready to be grazed again, managers typically look only at the plants that livestock most like to eat. Instead, grazing should be limited or stopped until most of the native species that make up a community have regained their health, which would give the site maximum immunity from cheat. Until the health of the land takes priority over the finances of ranchers, all the research and grazing schemes in the world won’t do much to shield native communities from cheatgrass.

Currently, when the agencies try to restrict grazing, it usually takes several years of laborious and acrimonious administrative procedures—and they seldom even try. Their reluctance stems partly from the enormous political influence that ranchers wield in the intermountain West, and partly from a lack of funding. Sometimes these two elements go together. By cutting funds for monitoring while adding a painstaking monitoring process to the burden of proof already borne by range managers, the BLM has made it very difficult to keep livestock off public land. One BLM manager says, “We’ve been such a tin-cup-on-the-corner agency, especially in the eighties, that we can’t do the monitoring. We see that the land is beat to a pulp, but data is everything in a courtroom.”

The inadequacy of BLM range supervision is widely evident. Even in the relatively flush Bruneau Resource Area, in the Snake River plains, the range program employs only six people, all buried in paperwork, to oversee 2.5 million acres. Only one of them monitors the allotments full-time, and for most of the past six months that person has been pulled away by other duties and lias hardly set foot in the field.

In addition to trying to defend native plant communities from cheatgrass, land managers sometimes take the offensive. 1’hcy remove cheat by tilling or prescribed burning—or with herbicides, though the use of them is entangled in legalities and safety issues at the moment. The proactive approach enables managers to choose the sites they want to restore, but they must choose carefully, because mounting an offensive against cheatgrass is expensive. An effort in 1991 to rehabilitate 1,700 acres in the Snake River Birds of Prey Area cost about $100,000—90 percent of the rangeland-improvement budget for an area of more than two million acres, much of which could stand improvement. And devoting 90 percent of that money to a restoration effort was a courageous anomaly. The livestock industry usually sees to it that most range-improvement dollars go to water tanks, pipelines, and other projects to augment grazing. Perversely, items like water tanks and pipelines sometimes encourage livestock to roam farther afield, and they end up degrading reasonably intact native communities.

Even lavishly funded rehabilitation efforts can never be more than limited surgical strikes. As Mike Pellant says, “There’s not enough money in the U.S. Treasury to get cheatgrass out of everywhere.” For the foreseeable future, even if all the needed changes in attitude and funding are made, range managers in the intermountain West will have to settle for trying to contain cheat and mitigating the environmental harm it causes.

A growing number of scientists consider the alien invasion to be an environmental problem on a par with habitat loss and pollution, yet no comprehensive study of nonindigenous species in America was undertaken until the Office of Technology Assessment mounted such an effort two years ago. Due out early this summer, the OTA report will show that the problem is huge and growing; though cheatgrass is one of the worst offenders—arguably it’s the nation’s most destructive exotic plant—by no means is it an isolated case. Perhaps the report will provide the impetus to come to grips with alien species before their ecological and financial costs climb any higher.

—Robert Devine