AUGUST 7, 2005 Stranglehold 's deserts are choking to death

By Kathleen Ingley This spring, a plant called Sahara mus- decorative use and then escape into the Opinion tard stormed into desert fields that should wild. have displayed a rainbow of wildflow- Invaders are destroying the Arizona ers. The University of Arizona's Tumamoc desert. Hill research station in Tucson had just Instead of a bright mix of purple owl's three non-native species in 1906. By The enemies are aliens - not creatures clover, blue lupine and yellow desert 1983, it had 56. from another world but aggressive plants marigold, acre after acre was nothing but that aren't native to this area. solid green mustard. At Lake Mead This year's heavy winter rains gave in- on the Ne- vasive species a shot of adrenalin. Weeds on steroids. vada-Arizona line, the density reached Weeds that seemed a minor problem levels as high as 3 million plants per acre. became a major menace. These invasive plants can outcompete native species and fuel devastating wild- This is far more than a loss of scenery, These plants may be harmless in their fires. although that's serious enough in state native environment. But they go bad where tourism is a $30 billion industry. when they hit a place that lacks their They're burning and strangling the Invasive plants steal wildlife habitat. natural predators and diseases. Other to death. They reduce property values. They feed factors give them an edge, too. wildfires, which threaten lives, destroy The postcard views are disappearing: property and cost millions to fight. They grow rapidly. They produce mas- chollas glowing in the sun, spiky ocotil- sive quantities of seeds that remain vi- los tipped with scarlet flowers, saguaros Just how bad can a weed be? able for a long time - a single Sahara standing like sentries. mustard can have 9,000 seeds. Other states know all too well. The toll And the invaders, especially non-native of just one plant, leafy spurge, on graz- Many weeds seize turf by germinating grasses, are taking over. Up the Beeline ing and wildlands in Montana, North and earlier than native plants and outstrip- Highway toward Payson. Out U.S. 60 South Dakota and Wyoming is estimated ping them. By the time a sand verbena, toward Superior. Around Roosevelt at $129.5 million a year. a delicate wildflower, has grown an inch Lake. wide, Sahara mustard is a foot across. For many reasons, including our harsh More and more places have lost their climate and the barrier of the Grand Buffel grass, one of the nastiest invad- familiar cactus-studded landscape and Canyon, Arizona has had fewer weed ers, sucks moisture out of soil so effi- now resemble the African savannah. problems than other states. ciently that even trees can't compete. Paloverdes in thick stands of buffel grass "It's like turning the Sonoran Desert into But advance troops of exotic plants have become so parched that they "self- a farm for grass," says April Fletcher, been moving into the state for years. prune," dropping branches to reduce their Southwestern invasive species coordina- need for water, eventually pruning them- tor for the U.S. Fish and Wildlife Ser- Seeds hitch rides on vehicles. They come selves to death. vice. mixed in with feed and seed mixes from out of state. Some problem plants, like Weeds aren't just choking the desert, The wildflowers are going, too. fountain grass, are sold in nurseries for they're torching it. Unlike some eco-systems, such as for- Arizona-Sonora Desert Museum, "a few are far higher than the price of eradicat- ests, the desert didn't evolve with fire. decades from now, I would expect huge ing weeds. Adapted to survive the very driest years, areas of the desert to be reduced to native plants have sparse vegetation and wasteland." If we give up, some of the most breath- are spaced far apart, leaving most of the taking views of the Sonoran Desert will landscape open. Lightning occasionally Most of the animals won't be there any- only exist on old photos and postcards. starts a blaze, but it doesn't travel far. more. Not Gila woodpeckers, elf owls, hummingbirds or javelinas. Invasive species fill in all the spaces, ready to carry a fire for miles. Red The transformation is lethal to desert brome, a non-native grass, is a major tortoises, which perish in fires and lose culprit in stoking fires in the Phoenix the cover that protects them from preda- area. It fueled the lower elevations of tors. the recent "Cave Creek Complex" fire, searing about 50,000 acres of Sonoran It doesn't have to happen. But we must Desert and racking up $3.6 million in fire- mobilize quickly on several fronts: fighting costs. • Education. We have a lot of catching Saguaros and other plants of the Sonoran up to explain the threat and help people Desert never developed tough skins, recognize invasive plants on their own flame-resistant seeds or other strategies property. Reports about desert fires to deal with fire. Invasive plants, on the should emphasize that they aren't natu- other hand, come back thicker than ever. ral and identify the non-native plants that fueled them. Buffel grass forms dense bunches that have more than 10 times the fuel load • Information. Infestations must be needed to carry fire in the desert. mapped and analyzed. We need a better idea of the most effective modes of at- "The more it burns, the more frequently tack and more research on biological it will burn and the hotter the fire will controls. be," says Travis Bean, a researcher at . • Structure. Arizona is just starting to get organizations and cooperative frame- Buffel grass will fuel wildfires in winter, works in place to deal with invasive when we didn't have them before, pre- plants. Another urgent job is to set pri- dicts Julio Betancourt of the U.S. Geo- orities on which plants to fight and logical Survey. We're poised for more where. transportation disruptions from highway fires, like this year's closures of Inter- • Resources. Of course, we need more state 17 and the Beeline Highway. money. It's especially critical to step up weed management along roads: Runoff Cities are likely to see ferocious new and the warmth from asphalt create ideal blazes. In Phoenix, buffel grass infests conditions for invasive plants to grow and the slopes of Piestewa Peak so heavily spread. Volunteers can also play a big that you can see the tan patches from role, if there's an effective way to mobi- downtown high-rise windows eight miles lize them. away. Fountain grass has fed half a dozen fires at South Mountain Park this year. Some people will say that this invasion is too expensive and difficult to fight. The way we're headed, says Mark Dimmitt, director of natural history at the But the costs and risks of doing nothing