McNamee and his sources sounded the alarm loud and clear. This tough African grass, Pennisetum ciliare (sometimes called Cenchrus ciliare), which had been introduced to the Sonoran Desert as a wondergrass for cattle, was threatening the entire Sonoran Desert Upland biome.
A decade has passed, and the problem is now much, much worse. In fact, the severity and extent of the infestation has been increasing steadily since the mid-'90s, and in the last several years, it has exploded--probably because of the combination of drought, warming and the sheer population density of the plant. The situation, according to every scientist interviewed for this story, is now critical.
In spite of the frantic warnings of ecologists and land managers, and despite some valiant and surprisingly effective local efforts, the problem is now so acute that biologists view buffelgrass as an imminent threat to the entire Sonoran Desert ecosystem, and large-scale control efforts are only now getting underway.
This is how bad it is: Local biologists, ecologists and climatologists are more worried about buffelgrass than they are about development.
"The worst-case scenario," says Sue Rutman, botanist at Organ Pipe Cactus National Monument and leader of a determined, decade-long war against the plant, "is that we lose the big columnar cactus except in a few, protected places, and all the wetlands that are left, including places like Big Bend. That scenario is, I'm afraid, the most likely outcome."
Ann Phillips, who oversees habitat-restoration projects for the Tucson Audubon Society and serves on the city of Tucson's Habitat Conservation Plan Committee, agrees. "It's hitting critical mass. It is incredible that we've let it get to this point, and imperative that we take care of it."
Travis Bean, principal research specialist and coordinator of buffelgrass eradication and outreach at the UA Desert Lab on Tumacacori Hill, is blunt: "We are at the teetering point of eco-system conversion." Bean spends most of his time campaigning against the weed, and he and Julio Betancourt of the U.S. Geological Survey, a senior scientist at the Lab, are largely responsible for getting buffelgrass added to Arizona's Noxious Weeds List, an important if belated step in controlling the weed.
"If you want to see what will happen if we don't get after this stuff, go down by Hermosillo and look around," says Bean. "They've got more than 2 million acres of African savannah down there. The Sonoran Upland ecosystem is gone from those areas, and the only way it could come back is if you were to blade it all off and landscape every square foot of it."
Even that might not work: Once a grassland starts to burn, buffelgrass is there to stay. Unlike desert plants, these grasses like fire, and come up thicker than ever after a blaze, frustrating the return of fire-sensitive native flora.
Buffelgrass is woody and grows in thick, graceless clumps. It's ugly and aggressive, and can and does outcompete and kill native plants--from annual wildflowers to palo verde trees--by sucking up water and nutrients from the soil. It likes roadsides, watercourses and, perversely, the steep, south-facing hillsides that saguaros prefer. It invades and gradually dominates prime habitat for native vegetation--but it's the way it burns that most scares the people who know it.
Fire is now frequent in the ranchlands of Northern Mexico, says Bean.
"We've dodged a bullet so far in Southern Arizona, but in the last few years, we've started to see fire--a lot of fire--where we've never seen it before. The native plants have not evolved to withstand it, and it wipes them out."
Bean knows this is confusing for the public.
"We've been telling people that forests burn, that they have to burn, and people have begun to accept that. But desert fire is not natural."
And it's not good. The effect of intense fire on cactus is especially gruesome: The juices boil inside the skin, and the plants are cooked alive.
But buffelgrass fires not only ruin scenic views and eliminate habitat for native wildlife, bad as that is; they also pose a threat to life, property and land values, and threaten to erode the quality of life of every Southern Arizonan. The way buffelgrass burns, its excellence as fuel, should demand the attention of anyone who lives here, owns property here, vacations here or ever wants to visit--from the kings of the development and tourism industries on down.
You don't have to care about the pygmy owl or the willow flycatcher to care very much about buffelgrass.
Where did this monster come from? Well, that's one for the annals of the history of unintended results.
Some of our noxious, invasive weeds got here by complete accident--puncture vine, for instance. Others, such as Bermuda grass and fountain grass--the latter is closely related to buffelgrass--have been imported for landscaping and gone native. Buffelgrass, however, was introduced deliberately by range scientists, if not into Southern Arizona, then certainly into Texas and Sonora, Mexico, where it has been the basis of the cattle industry for several decades.
Tom Van Devender, an ecologist at the Arizona-Sonora Desert Museum who's worked on mapping the spread of Pennisetum, believes that the local infestation originated at a U.S. Soil and Conservation Service experimental farm on Romero Road, where scientists worked with exotic range grasses beginning in the 1930s.
Buffelgrass has been introduced into many parts of the world as forage for cattle, and has quickly gone wild in dry, open areas from South Africa to Hawaii to the Virgin Islands. (Trees can outcompete buffelgrass by shading it in the tropics.) And it's come to some places entirely by accident: It's thought that the seeds that started the infestation in Queensland, Australia--where it's a huge problem--dropped off the tack of a herd of imported Afghani camels.
Wherever it becomes established, either as a Green Revolution forage or as an unwanted weed, buffelgrass alters the landscape, squeezing out native species and quickly depleting nutrients in the soil. One of the many ironies that's emerged from the story of the human manipulation of buffelgrass is that it provides good grazing only for 10 to 15 years, after which the quality of the pastures decline due to nutrient exhaustion. And even in the early years, the pastures are difficult to manage. Ranchers have to move the cattle around constantly to keep the grass cropped and green, because once it matures into its dry, woody phase, it's practically inedible.
Mark Dimmitt, who directs the Center for Sonoran Desert Studies at the Arizona-Sonora Desert Museum, which is cosponsoring a border-weeds conference in Mexico this May, says that ranchers in Northern Sonora have become disillusioned with the grass, and, although the government of Mexico is still encouraging its cultivation, they're not planting it as much as they did 10 or 15 years ago.
"But it's spread from the pastures into adjacent thorn-scrub and, to some extent, into the oak woodlands," says Dimmitt. "South from Santa Ana (about 50 miles south of Nogales), there's nothing else along the road but buffelgrass all the way to the Sinoloan border.
"We simply do not know what will happen to the millions of acres where buffelgrass has crowded out the native vegetation and exhausted the soil. These are sterile, monoculture wastelands now, and no one knows what their future will be. It's very hard to see how the native plant and animal communities will ever come back in."
Dimmitt says he and his colleagues recently discovered that buffelgrass is also more prevalent on rangelands north of the Arizona-Mexico border, where it has never been cultivated, than they had realized.
"We were seeing it all along the roads, but not on the other side of the fence until we started getting out and really looking. Then we saw it was established everywhere, but the cattle were keeping it short. We think that at this point, cows are actually protecting a lot of Southern Arizona from conversion to savannah."
When the native plants go, the birds and animals disappear with them. Aside from cows and ranchers, only rabbits, locusts and ants flourish where buffelgrass has taken over. Van Devender, who's looked at buffelgrass from Organ Pipe to Chihuahua, says he once saw a rattlesnake in dense buffelgrass.
Once.
"Vertebrate diversity plummets," he says. "And of course, once you get a fire, everything is gone."
He recalls a granite knob in Northern Sonora that was a popular spot for desert tortoises when he first surveyed it. It sat up above the sea of buffelgrass, which subsequently burned. The fire swept up and over the knob. When Van Devender went back, there was nothing but rough, bare rock.
"The fire burned so hot, it popped the weathered surface sheets of the granite right off. No tortoise could have survived that."
Neither the limitations of buffelgrass as forage nor its capacity to lay waste to whole ecosystems has discouraged research scientists at Texas A&M University, who, with the support of the U.S. Department of Agriculture, have been diligently fiddling with the plant's genes to produce even tougher, more aggressive varieties of Pennisetum. Last year, they announced a new strain, Frio, which is more cold-resistant than any existing variety. Frio was recently introduced on a ranch 40 miles south of the Arizona-Mexico border.
The idea of frost-tolerant buffelgrass invading Southern Arizona appalls ecologists.
"One degree centigrade lower frost tolerance means that it can grow another 100 to 150 miles further northward, and, of course, higher up the mountains," says Bean. "We're estimating to 4,500 feet or so around here. That means a fuel ladder that runs right up from the valley floor to the oak woodlands and on up to the tops of the mountains."
In other words, desert fires that crown on Mount Lemmon.
Since buffelgrass is a noxious weed in Arizona, Frio cannot be imported into the state. But if it's like its sister strains, it will come: on the wind, in the beds of pickup trucks, on the hides of animals.
"Oh, a dust devil will carry those seeds for miles," says Dimmitt.
It's certain that the border won't stop it. Out at Organ Pipe, Sue Rutman, who's done wonders keeping the monument clear with just crews of volunteers hand-pulling the grass, has had to stop sending crews in along the border because of the danger posed by smugglers. She says that she's now seeing buffelgrass re-establish itself there and in pockets in the backcountry. Buffelgrass grows densely just south of the fence.
"It's likely that the drought is favoring it, and I think I'm seeing new genotypes," she says.
In other words, the grass may be evolving on its own, adapting even more successfully to its new habitats.
Buffelgrass efficiently converts desert from an essentially fireproof environment to a highly combustible one. As the grassfires endemic to Southern California and recent drought-related wildfires on the natural prairies of Oklahoma and the Texas Panhandle show, grass fires can be even more dangerous and destructive than large forest fires. Grass fires tend to burn across wide fronts and move very fast. And many more people live amid grasslands than in the woods.
(Betancourt, a climatologist who's an expert on weather and fire, predicts that if the weather stays dry, there will be even bigger fires later this spring in the cattle lands of South Texas, where buffelgrass is cultivated and now dominates the landscape: "We are going to see big, big prairie fires in South Texas if it doesn't rain.")
The destructive potential of non-native grasses in the desert became clear last summer north of Phoenix. The lightning-caused Cave Creek Complex Fire burned through a quarter-million acres, 10 to 20 percent of which was Sonoran Desert carpeted with red brome, wild oats and other non-native grasses. It killed an estimated 80 percent of the desert vegetation it rolled over, including the world's largest recorded saguaro, and cost more than $16.4 million to fight. Like all fires in dry grass, it moved with frightening speed.
And the Cave Creek fire was just part of the worst fire year in Arizona history: There were more than 2,000 recorded fires in the state last year, and they burned more than 700,000 acres. Ominously, 2005 was an El Niño year, with decent winter rains--unlike this year.
"That hasn't happened here in 10,000 years," says Betancourt. "But we are looking at big changes in weather and vegetation. Huge fires that start in easily ignited lowland fuels and then progress into heavy upland fuels--that's the shape of the things to come in Arizona unless we get a handle on invasive grasses."
Betancourt and Bean worry not just about the desert, but about what can happen anywhere human habitation meets buffelgrass--which is all around Tucson. Hundreds, perhaps thousands, of homes on the edge of the city are standing knee-deep in tinder-dry grass, or near steep slopes and roadsides blanketed with it.
"One of these days, we're going to get a bad, bad fire when somebody throws a cigarette out of a car window onto a shoulder covered with grass, and the fire runs up to a house and takes it out with the family inside," says Betancourt. "I could drive you around and show you one place after another where it could happen."
Nor is the threat confined to the periphery. Vacant lots and washes running all through the city are already choked with flammable, non-native grasses, typically Bermuda grass. But hot-burning buffelgrass is taking over the sunniest locations.
Last November, a homeless man died when a patch of buffelgrass caught fire in a vacant lot off 44th Street. He had third-degree burns over 90 percent of his body.
"When we heard someone had died in a 'brushfire' down there, we guessed what had happened," says Betancourt. "Homeless people are camped under mesquites all over empty land around the airport and Davis-Monthan, and under the trees, you've got that mix of Bermuda and buffelgrass. Sure enough, when Travis went down to look, he found that the fire was in buffelgrass. We called the police and told them what had happened. I don't think they believed us. It's still listed as a suspicious death.
"All it took was a spark."
In the last year or two, awareness of the problem, like the infestation itself, has snowballed, and both citizens' groups and government agencies have started to move.
"People say, 'Oh, this is too widespread already--we can't deal with it,'" says Betancourt. "They just haven't realized what it means not to deal with it."
The Audubon Society's Phillips says the community needs to step up--now. "And we will have to keep after all these invasive species--fountaingrass and tamarisk are big problems, too, and they're not going to go away. We can't assume that the desert will take care of itself anymore. This is a permanent commitment, and it will go on forever."
Some containment efforts include:
· The Arizona Department of Transportation has begun spraying buffelgrass with herbicide along Interstate 10--an important and long-overdue move, according to biologists. (Roads seem to be the major vector by which the grass spreads.)
· The Groundskeeper, working for the Pima County Department of Transportation, has been clearing the grass from roadsides in the foothills.
"They cleared just about all First Avenue between Orange Grove and Ina roads in November and December, and now they're working on Ina," says Betancourt. "They're moving right along. Pima County is really going after it, and they need all the support they can get for the job they're doing."
· This summer, the city of Tucson will start spraying the herbicide Roundup on massive buffelgrass infestations and studying the results on retired farms the city owns in Avra Valley. Then they'll try various methods of restoring native vegetation.
Using herbicide on its more than 20,000 acres is something the city was reluctant to do, says Leslie Liberti, manager of the city's Habitat Conservation Plan, until biologists on the planning committee told the other members that "there would be nothing to conserve" unless they got rid of the buffelgrass. While no one in the life sciences likes herbicides, Roundup is almost wholly absorbed into the plant and breaks down quickly in the environment. And the infestation is too big to treat any other way, says Phillips, who is overseeing the restoration phase of the project.
"Besides--hello?--this is farmland that was soaked with every chemical under the sun for years," she says.
· Travis Bean will be spraying Tumamoc Hill "as soon as we see green shoots after the summer rains start." Hand-pulling on the steep sides of the hill is too dangerous for workers, he says, and too likely to cause erosion. In addition, no digging is allowed on the hill without a permit because of its fragile archeological sites. "We're going out there with backpacks and hitting individual plants. It won't be hard to avoid spraying the native vegetation."
· The Bureau of Land Management has begun a regular volunteer buffelgrass-whacking program in Ironwood National Monument, and the Forest Service has one up and running in Sabino Canyon. Both are modeled on the very successful Sonoran Desert Weedwackers, a volunteer effort that has cleared much of Tucson Mountain Park of buffelgrass since its inception in 2000 (see "Territorial Triage," Currents, Nov. 18, 2004). All these programs owe much to Sue Rutman at Organ Pipe, who started taking out buffelgrass when she went to work at the monument in 1994. She and her crews have pried up and pulled an estimated 150 tons of the grass, and most of the area that has been cleared has needed only minor follow-up.
· Both units of Saguaro National Park inaugurated exotic plant control programs in January.
· Neighborhood associations around town have gotten busy pulling buffelgrass and fountaingrass. On the westside, the grass-choked neighborhoods around A Mountain and Tumamoc Hill have been organizing crews for some time. Travis Bean is trying to educate and radicalize every possible organization on the issue, and is available for free presentations to interested groups.
"We have a pretty good presentation," said Betancourt. "We went up and gave it up at the governor's office in 2004, and within two weeks, buffelgrass was listed. The state is now aware that this is a big problem."
Arizona is way behind the curve, though. ADOT's budget for roadside maintenance, which is critical both to control of the plant and to fire prevention, is tiny compared with that of most states. Still, government seems to be coming to terms with the end of the low-maintenance Sonoran Desert more quickly than the general public is.
Betancourt says that one thing that needs to change is the way the media talk about fire: "We have to raise consciousness about fire prevention to buy time for the desert while we get rid of the grass. And 'brushfire' doesn't cut it anymore. The public needs to know not who, but what causes a particular wildfire, what fuel and conditions made it possible.
"We need awareness and action at the grassroots, so to speak," he says.
Bottom line--the public needs to get upset about buffelgrass. Very upset. Or we may all have to say goodbye to the saguaro.
