Wicked Reeds : Experts Hunt for Ways to Kill a Resilient Exotic Transplant Threatening Two Endangered Species

Call it the plant from hell.

Arundo, a tall bamboo-like exotic plant, is creating environmental chaos in the quiet canyons of Angeles National Forest above Santa Clarita.

The stubbornly resilient arundo--which can grow to heights of 25 feet--clogs streams and muscles out native plants. Birds won’t nest in it and, apparently, nothing will eat it. Fire and drought won’t kill it. And if you chop it down, it grows right back.

“I’m sure a swarm of locusts wouldn’t hurt it,” said Shawna Joyce, a wildlife biologist with the U.S. Forest Service, as she recently surveyed a grove of arundo in the national forest above the Santa Clarita Valley.

Yellowed by winter, the arundo--brought to the United States from Morocco years ago to control erosion--looks like a field of giant wheat filling a ravine in San Francisquito Canyon. The slender shafts tower above willows and cattails and surround the trunks of cottonwood trees, leaving only the branches visible.

“It has gone just hog-wild,” Joyce said.

Worried Forest Service officials are studying ways--including the use of herbicides--to destroy the pesky plant, which is slowly destroying the habitat of two endangered species. Joyce is spearheading the eradication effort.

Arundo can be spotted from San Francisco to San Diego along roads, in flood control channels and beside streams. The plant is found occasionally in other parts of Angeles National Forest above the San Gabriel Valley. The “giant reed plant”--as it is also known--is spreading in Los Padres National Forest in Ventura County as well, and forest officials there are keeping an eye on Joyce’s eradication effort.

But, for unknown reasons, arundo seems to prefer the canyons above Santa Clarita, Joyce said. And the forestry staff there is finding methods for its eradication limited and laborious. The most successful assault was developed by biologists in San Diego County, who discovered that, by cutting the stalks to about a foot in height and then spraying or painting the stumps with herbicide, they could control its growth.

But even this method has drawbacks, said John Rieger, a biologist working to keep Caltrans projects free of arundo in San Diego.

Work crews must apply the poison within five minutes of cutting the stalk because the arundo quickly seals the wound with a protective layer, making it impervious to poison. What’s more, this method only works in the fall, arundo’s prime growing season.

“It’s an extremely durable plant,” Rieger said “Burning won’t kill it. We’ve tried that.”

In fact, fire helps arundo spread. The giant reed sprouts back to life almost immediately after a blaze and dominates the landscape before native shrubs, bushes and trees can re-establish themselves, Joyce said.

Although thick arundo groves may weaken existing trees and shrubs, they probably won’t kill them, Rieger said. But the arundo, blocking out the sun with its thick canopy, will prevent the next generation of trees and shrubs from growing, he said.

Arundo is not just crowding out other plants. It is slowly destroying the habitat of some animals as well.

In Angeles National Forest, arundo mainly grows in and along stream beds that are the habitat of the least Bell’s vireo, an endangered songbird, and the unarmored three-spine stickleback, a tiny endangered fish.

The fish need running water, but thick blocks of arundo form miniature dams, causing the water to stagnate, Joyce said. The vireos prefer stream beds lined with a mixture of shrubs, bushes and trees. When arundo takes over, the stream bed is covered with a monotonous, green blanket the birds can’t even fly through.

The persistent plant can form large bamboo-like walls blocking off streams from deer, coyotes and other large animals.

The Forest Service is accepting comments from the public on its proposed three-year eradication program. If plant poison is used, it will likely be Rodeo, a herbicide for aquatic areas approved by the federal Environmental Protection Agency. The agency lists Rodeo as nontoxic to fish and animals, Joyce said.

Joyce stressed that the herbicide is just one option under study. “In no way have we decided what we are going to do,” she said.

Rieger, who has used Rodeo on the giant reed with success in San Diego, said most biologists generally avoid using poisons to control exotic species. But this plant, he said, leaves biologists few other choices.

“This is one area where a controlled use of chemical herbicide is justified,” he said.

Joyce said she hopes to develop an eradication plan by fall. By then, of course, the arundo will have grown a little taller and have spread a little farther.

As she recently drove down San Francisquito Canyon Road in a Forest Service van, Joyce recalled the roadside mailbox of one of the canyon’s many ranches. The arundo had grown so dense that the mailbox could hardly be seen. The rancher grew so agitated he whacked off the stalk.

A few months later, she said, the arundo was once again standing tall and the mailbox was hidden from view.