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Looks Are DeceivingNoxious weeds tend to have ominously evocative names: devil’s foot, hawkweed, bindweed, ragwort, cheatgrass. Yellow star thistle, by comparison, sounds almost benign. But it’s a sinister fellow, dominating hillside after hillside in the canyon, 280,000 acres in Idaho, more than 8 million acres across the West. The plant first came to North America from Mediterranean countries in tainted loads of clover seed or alfalfa shipped to California in the Gold Rush days. From there, it has marched steadily east. It bears a pretty yellow flower, but that’s the only nice thing to say about it. Once it takes root, it tries to squeeze out everything else that might want water or soil or sunlight. And it often succeeds because it’s aggressive enough to elbow out native plants that took thousands of years figuring out how to live in this harsh place. Once star thistle has a foothold, it just keeps pushing, creating millions of seeds and sending them traveling on animal hair, vehicles, boot laces, the wind. It has incredibly tough thorns, as sharp as a prickly pear but not as long, and it carries these weapons about thigh-high on a human. Walk through a field of it in short pants and you’ll bleed. Not much will eat it. Chukars, maybe, and some grazers if they’re hungry enough. But if a horse nibbles the springtime rosettes, before the spines form, the thistle causes a sort of craziness called chewing disease. And it’s both opportunistic and patient. It can germinate in 16 hours, or it can lie dormant in the soil for seven years. Come spring, star thistle is out of bed early, growing fast while the native plants think it’s still winter. Nasty stuff, as Talsma says. Scouting From the AirYellow star thistle is what sends us careening through the canyon in the helicopter. Mike Atchison is an Idaho field representative for the Conservancy, and his job often puts him in the helicopter’s front seat, where he straps a hard, military style laptop computer to one leg so he can use both hands to enter data. He’s a little casual about the demands of his work, which has the technical name of Digital Aerial Sketch Mapping. “You need three skills,” Atchison says through the rotor wash and the music on the radio, which has switched to some kind of head-banging thing. “You’ve got to be able to identify weeds, be good on the computer and not get sick.” The basic sketch-mapping process has been around since the 1940s, when the Forest Service put people in airplanes, armed with paper maps and pencils, and told them to chart infestations of tree-killing insects. Later, the service incorporated big computers, but their approach was so clunky and expensive, hardly anyone used them. Jason Karl, a spatial ecologist at the Conservancy, thought the concept could be used for weed eradication, so he brought the technology up to date, making it smaller, cheaper and easier to use. “It doesn’t require a professional geek like me,” says Karl. “Give us a person with an iron-clad stomach and a few hours of training, and we can get them going.” Atchison says his stomach is pretty solid, but others can’t tolerate the flying — the spinning, the sideways dives, the dipping and climbing — let alone do it while constantly shifting their eyes from the ground to a computer screen dense with graphics. If you’re 100 feet in the air, you’re too high to spot the weed patches, so you hug the ground. But that doesn’t mean you slow down. “It’s fairly demanding flying,” says Jim Pope, who’s piloting the bright-red Hughes 500 and grinning the whole time. “You’re not going to fly with just anybody,” Karl cautions. “You’re only going to fly with a really good pilot.” Pope is one of them, a second-generation backcountry pilot who flew in the military and as a firefighter. But for this mission, he says, he applies skills he learned as a crop-duster. When Pope gooses the machine up to 140 mph, he’s the one who cautions: “Don’t put your arm out the door. Or you’ll lose it.” Pope’s helicopter has become an invaluable tool. Since Hells Canyon is so vast — up to 20 miles wide and 140 miles long — human feet can’t keep up with the spread of weeds. Roads are scarce here, and trails only skirt most of it. Even with mules and jet boats, you can’t cover it all. “The helicopter is really the best way to cover lots of ground,” Atchison says. “There are places mules can’t even go.” But the helicopter lends a hand only if it carries the sharp, trained eyes of people like Atchison, who can spot the delicate violet blossoms of knapweed or the yellow spray of star thistle, while holding down their lunch. Atchison’s computer has a wireless link to the GPS unit on the helicopter’s dashboard. As he flies, the map on his screen constantly changes to reflect what is below him. When he spots weeds, he marks the location on his computer screen with a stylus, noting the size of the patch and the species of weed. Later, he downloads the information. Then people with hand-held GPS devices use the data to make a beeline for the weeds. Without those coordinates, the weed patrol would have to hike hundreds of miles in a grid searching for the invaders. This groundwork is where the SWAT team comes in, carrying weed killer in tanks or weevils in paper cups. “We definitely run a lot of search-and-destroy missions,” says John Sugden, a member of last summer’s SWAT team. The sketch mapping lets the SWAT team do a lot less searching and a lot more destroying. Nature picture credits: Photos © Karen Ballard |
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Copyright © 2008 The Nature Conservancy
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