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Natural Enemy

Officials Struggle to Control Invasion of Waterways by Nonnative Plant


It creeps through waterways, growing 20 feet high, with long green limbs that leave a wasteland in their wake.

Even its name sounds alien: Arundo donax.

The plant with the nearly unquenchable thirst sucks up precious water, chokes out vulnerable natives and spreads amoeba-like from a single fragment.

The march of this relentless bamboo-like grass is proceeding across Southern California, unabated in some places. With wars already raging in Los Angeles, Orange, San Diego and Riverside counties, the battle in Ventura County is just beginning--slowly, and, some say, too timidly.

But not a moment too soon, according to conservationists. Arundo is public enemy No. 1 to Ventura County weed fighters.

And it's going to take 20 years and millions of dollars to fight a plant that grows ravenously in waterways throughout the county--increasing by an estimated 10% a year and creating expanses of giant reed in places as disparate as the Ventura River watershed and plots outside The Oaks mall in Thousand Oaks.

"It's the thing that wouldn't die," said Pam Lindsey, a county flood control biologist who is working with a task force on a pilot project exploring eradication of the plant.

The project is the first local step in confronting the invasion of nonnative flora that is upsetting the balance of nature in California.

The foreign invaders were brought by Europeans several hundred years ago, and the takeover continues as the plants escape from behind garden walls to squeeze out native flora and reshape coastal dunes.

Arundo donax, what some call false bamboo, giant cane or giant reed, was brought from the Mediterranean by Spaniards to stem erosion and to roof some of their missions.

It can grow several inches a day and reach heights of 25 feet. Within months, it can grow so thick that it becomes a dam, diverting stream beds. Storms wash fragments downstream, further spreading the plant and creating wastelands where no other life can exist. And when the dry stuff catches fire, its feathery leaves float on the wind, easily spreading the flames for miles.

"Birds won't nest in it and critters won't use it," said Ron Bottorff of Friends of the Santa Clara River.

That means an increased risk to such already endangered bird species as the least Bell's vireo, southwestern willow flycatcher and the warbling vireo, as well as to the steelhead trout, cut off from upstream spawning grounds.

But "finally, after years and years of talking and throwing up our hands, [officials] are realizing it's not going to get any better," Bottorff said.

Conservationists say that fighting the arundo--which leads such alien species as castor bean and tamarisk on the county's list of invaders--is one way to stop the creation of a monoculture, an ecosystem ruled by one form of life that forces out all others.

"On some level, you could say, so what?" said David Magney of the California Native Plant Society. "But it's not really evolution, because we created the problem. Evolution happens on a natural scale, not [caused] by humans."

Arundo serves few useful purposes. One company used the stalks for reeds for woodwind instruments, but the business is gone now. And in the river bottom, arundo sometimes provides a place for the homeless to hide.

Now the question isn't whether it should be eradicated, but how.

The weed has been a problem for years, battled scattershot by public works agencies and city crews, Boy Scout troops armed with pickaxes, and developers forced by law to do some good to pay for their developments.


A Ventura County task force formed two years ago to wipe out the plant is expected to finally begin its battle this summer, with a $60,000 effort along the Ventura River, where the stuff grows thick along Casitas Springs trails.

Peggy Rose, project manager for the county's resource conservation district, shudders at the scope of the task.

"People have noticed it for years, but this happened fairly quickly," Rose said. "It got out of hand before anybody realized it."

Rose first plans to clear a 4,500-by-50-foot trail of the weed from the Ventura River watershed. The plant can't just be chopped down once--the roots dig in. So workers will have to place herbicide on the stumps for at least five years.

They must start at the top of the plants and work their way down, to stop the spread of fragments.


Then they have to figure out how to get rid of tons of hacked-up reeds. Some will go to fix a mission roof near Lompoc. Some could be sold for particle board. Some may have to be burned.

This site was chosen because it's visible, along the paths where people can see the plant being removed. But people seem to like the reeds, which Rose doesn't understand.

The plants can be purchased at nurseries, despite all their faults: the fire potential, the monoculture, the fact that, as Rose says, they may be as big a threat to the endangered steelhead trout as the Matilija Dam, which also blocks the fish on their run to prime spawning grounds upstream.

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