Alien invasion: Parts of Nevada overwhelmed by non-native vegetation

Phil Hagen

Saturday, Oct. 4, 1997 | 6:45 a.m.

The aliens have already taken over and there's no independence day in sight.

While we search the skies for invaders, another life form has been here for years, attacking right under our noses. And it has hit the desert where it hurts the most: our parks, our wetlands, our water supplies.

This species, tamarix ramosissima (better known to earthlings as tamarisk or saltcedar), first landed somewhere around western Texas or New Mexico late last century when someone thought it would make a nice ornamental plant or a stabilizer for streambanks. Maybe it did in its homeland, Eurasia, but on foreign soil, without its natural enemies, it went wild.

It went wilder when we harnessed the rivers of the West with dams and diversions, interrupting the flow of nature. The elimination of spring floods cramped the life cycle of native vegetation, such as cottonwoods and willows, and paved the way for tamarisk, which produces a prodigious amount of seeds over a long period.

Not that tamarisk needed help competing. The thirsty colonizer crowds out its neighbors by hogging their water, then keeps them out by leaving the soil dry and salty.

Today, it occupies more than 1.5 million acres in the West -- and it keeps growing.

"A lot of people out here think it's just a natural tree," says the National Park Service's Curt Deuser, who oversees the nation's first tamarisk control crew, based at Lake Mead National Recreation Area. "They don't even realize it's exotic, because it's everywhere."

It is a cancer. "Oh, major, major. Big time," says Stan Smith, the UNLV biology department's resident tamarisk expert.

It has displaced native wildlife at places such as Ash Meadows in Nye County and is sucking up valuable water from the Las Vegas Wash. The Virgin and Muddy rivers may never be the same. Anywhere there's water in the desert -- from road-side ditches in Green Valley to the dry lake in Eldorado Valley -- there's the risk of a similar fate.

"The damage that it is doing to the environment and to the ecology of an area is just unbelievable," says Nevada Division of Agriculture entomologist Jeff Knight in Reno.

Knight hopes to help with the introduction of a biological control -- imported tamarisk-eating pests -- into Nevada. The pests can't stop tamarisk; experts only hope they can contain it. But concerns over containing the pests themselves have kept the potential breakthrough in the laboratory.

Meantime, the tamarisk's tiny seeds are frequent fliers to other fertile grounds -- sometimes hundreds of miles from their origin. And efforts to cut into its current population usually just make the tamarisk mad.

It's enough to keep a land manager awake at night.

"I have had dreams," sighs Eddie Garner of the Bureau of Land Management, "and they're not very pleasant."

Garner, a soil scientist with the Las Vegas district, is living and breathing tamarisk these days. That's because, on the BLM's 4 million acres in Southern Nevada, there are about 10,000 infested acres. Most of the district's 200 springs already have been invaded; for the rest it's only a matter of time.

The cancer at Hiko Spring, in the Paiute Valley about six miles west of Laughlin, is in the advanced stages.

A few decades ago, this was a diverse oasis in the desert. On the floor of a sacred canyon, whose stones are a museum of ancient Indian petroglyphs, spring water quenched cottonwoods, willows, mesquite and other native plants and grasses, which in turn fed a variety of fauna -- from bighorn sheep and coyotes to dove and quail.

Now it's mostly tamarisk with a trickle of water. For 2 1/2 miles, the stands have woven a thicket so tight most animals cannot penetrate it. Its floor is so shady, salienated and thick with duff that no plant can grow. Its seeds are inedible, its limbs fruitless and leaves salty, making it undesirable as a place for most birds to feed or nest. The water it has absorbed from its main root -- a tap that goes as low as the tamarisk is high (up to 20 feet) -- has left little for plants that were there first.

The native species are conspicuous by their absence, Garner says, as well as in their struggle to compete, as in the case of one cottonwood that has tried for about 10 years to get along with the tamarisk.

"That one dead cottonwood stands as a symbol of what happens to native plants when they have moisture deprived of them," he says.

Quite a victory for tamarisk, considering the hearty nature of cottonwoods. Even the normally invasive cattails have been pushed aside.

"When cattails can't compete, nobody can," says Peter Crookston, a wildlife biologist with the BLM.

Slaying the beast

Crookston is out at the Las Vegas Wash on a hot, late-summer morning, squirting another coat of herbicide on tamarisk stumps left from a crew's cuts a month before. That group, BLM hot shots from Mississippi, had slashed its way through a half-mile stretch along the wash before getting called to a wildfire. In their wake, within five minutes of each cut, certified BLM sprayers such as Crookston had to hit each sprig and stump. A few minutes too late and soon a stump will shoot up a dozen more sprouts, Garner says.

Even with precise timing, that practice isn't always perfect.

Garner points to a large stump and its log, laying alongside. It's been completely severed and sprayed, but still has new life coming out of it. "That's how aggressive it is."

Still, they hack down the thickets, hoping simply to return these delicate desert areas to the way they were. So far, so good, Garner says. About 80 percent of the stumps have not resprouted. And without the thirsty tamarisk, the trickle of water is practically a rivulet.

This crew, hot shots from Las Vegas, is at Hiko for a couple of days to cut some more tamarisk and burn the slash piles from the previous effort. They or another crew will be back next month and again early next year to remove the remaining two-mile stretch -- providing there is federal funding. The agency has already run up an $11,000 bill.

"It takes a lot of time and effort, and it's very expensive," says Sid Slone, head of the BLM's local wildlife division. "But we're gonna see a lot more effort go into it over the next 10 years."

Fed vs. fed

Tom Smigel is uneasy about the government getting bolder in its tamarisk removal. A native species himself, he has witnessed the tamarisk's impact on the wash as well as the benefits of removing it.

But he's also concerned about the herbicides they're using to do the job. He owns water rights and a grazing allotment at the spring, where he wants to produce an organic crop -- date palms. He's writing an appeal and request for stay against the BLM's application of herbicides there. "But that's just me on the personal level," he says.

As regional manager of the U.S. Department of Agriculture, he points to a cottonwood tree and two willows as being symbols of the damage a nonselective herbicide can do.

"The cottonwood is burned 50 percent, one willow is dead and the other one is burned significantly," he says. "So they got rid of the tamarisk, but damaged the vegetation they want to keep." (Garner is confident the old cottonwood will bounce back.)

Smigel believes the agencies need to pick their weapons carefully.

"There are places where it's worth doing," he says. "But tackling the Virgin River or the Muddy River flood plain for tamarisk, I just think it's an impossible task. They're wasting their money trying to kill something they can't kill."

The war room

A major counterattack against tamarisk is sprouting. Agencies from Nevada, Utah and Arizona are joining forces to come up with a strategy. They recently started meeting once a month to develop a management plan and to increase public awareness. When all is in place, including their weapons, they'll advance to the first battlefield -- the Virgin River area near Mesquite, where thousands of acres have been invaded.

The allies against the alien, calling themselves the Virgin River Basin Tamarisk Work Group, include about 10 agencies and, they hope, everyone else affected by the invasion, such as private landowners.

"There has to be 100 percent involvement," Garner says. "Ninety-nine percent doesn't work, because anything less than total involvement would not prevent the spread."

Since tamarisk crosses all boundaries, he says, it's everybody's nightmare.

"I think the biggest benefit is we've recognized a common enemy and suddenly everybody starts communicating for a change," says Bruce Sillitoe, principal environmental planner for Clark County, which is involved in the Virgin River group.

"Certainly the Park Service has recognized it as a problem and the need to control it in the park, and they have done a pretty dang good job of it. They can do everything around the park, but if you have the Virgin River and the Muddy River as a major seed source, you're never gonna make a dent."

With Hiko Spring, the Park Service convinced the BLM to spring into action against tamarisk.

"They've done well," says Deuser, a Park Service resource management specialist. "They're starting to be more proactive.

"There's an area we went into in 1993 (Sacatone Wash) that was just like Hiko. Now it's a lush oasis, with hundreds of willows and cottonwoods and aquatic plants. It's functioning again. Hiko Spring has all that potential."

Garner is pleased with the early returns. He's calculated that the creek's flow has more than tripled since the first cutting a month ago. Soon, he hopes, the native trees will make a comeback.

"If we don't see any, we'll come back and plant some," he says.

Professor Smith believes such reclamation will be necessary.

"I have argued that you're not gonna get back the original system you had, at least not in the near future, because the saltcedar has changed the landscape," he says. "It's lowered the water tables, which might come back, but you also have a salt buildup in the soils, especially if (the tamarisk) has been there 20, 30 years."

It's still worth the sweat, says Dave Phillips, a BLM resource management ranger, who expended a lot of it spraying the Hiko stumps in the hot sun.

"I'm glad to see the government starting to rehabilitate places like this," he says. "It's a good feeling to get rid of this stuff. I'd be happy doing this the rest of my life."

He may have to.

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