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Biological Warfare

Alien Plants
Janet Orsi

Alien Invader: Ann Howald, president of the Caifornia Exotic Pest Plant Council, stands amid the dreaded Arundo, also known as giant reed grass, coming soon to a neighborhood near you.

Alien species have escaped from their native habitats and hit California's shores.

By Christopher Weir

LIKE THE RED MARTIAN weeds that engulfed England in The War of the Worlds, German Ivy is invading the California coast, creeping over the Santa Cruz Mountains and advancing toward Silicon Valley. It's not going to slither over the concrete and assault anyone at the coffeehouse. But if it did, people would know exactly how thousands of local trees feel.

"It just smothers and shades out everything in its path," says Don Thomas of the California Native Plant Society. "It's a huge problem."

But certainly not unique. As dozens of invasive plant and animal species near critical mass, ecosystems of the South Bay and beyond are increasingly being pushed toward the brink of ecological ruin. From French broom to periwinkle, the red fox to the European green crab, nonnative species appear to be gaining unprecedented momentum in Santa Clara County. This parallels global trends.

"A lot of these problems start slowly, then accelerate," says Thomas, chair of his group's Escaped Exotic Plant Committee. "And now we're in the accelerated phase of this process."

Andrew Cohen, a marine biologist with the San Francisco Estuary Institute, concurs.

"We're losing our biodiversity and essentially seeing the same set of weed organisms from place to place as we go around the world," Cohen says.

A Bad Movie

LIKE THE VIRUSES that gained notoriety through a couple of movies last year, exotic species occupy the dark side of global intimacy. They are the inadvertent byproducts of modern transportation, as well as population sprawl. And they are now wreaking unprecedented environmental havoc, and that is having a financial impact.

The Nature Conservancy reports that the 79 worst alien species have already cost the U.S. economy $97 billion. While the environmental toll cannot be quantified on such a large scale, the Conservancy says exotics are second only to habitat destruction in chasing native species into extinction.

Of course, many nonnative species have been integrated into what's considered our natural environment. Eucalyptus trees, horses and wheat, for example, seem right at home in the hills outside San Jose.

And some insist that humans are the ultimate intruder, as the primary vehicle for nonnative species' introductions.

The growing trouble with exotics, however, concerns species that reproduce fanatically, vandalize indiscriminately and flourish unchallenged by the native environment.

'A lot of these plants and animals had something in their native habitats that controlled them, that kept them in check," Thomas says. "In new environments, they have no natural enemies, and so there's nothing to limit their spread."

In other words, alien species often infiltrate landscapes with all the grace and sensitivity of cancer. It's only recently, however, that this ecological disease has been detected by most people.

"It wasn't many years ago," says Ann Howald, president of the California Exotic Pest Plant Council, "that if you tried to talk to people in a serious way about the ecosystem impacts of exotic organisms, they would think you were absolutely nuts, some kind of wacko."

German Invasion

LOCALLY, GERMAN IVY is just one of many alien plants that are taunting conservationists with their resilience and vigor. Periwinkle, English ivy and French broom are rampant in the Santa Cruz Mountains, while yellow starthistle is especially attracted to the more temperate climate found in the Santa Clara Valley.

Ken Moore, director of the Wildlands Restoration Team, a volunteer group working to eliminating invasive plants from state parks in the Santa Cruz Mountains, says Scotch broom (or French broom) bushes "over-top" their neighbor plants and deprive them of sunlight.

"They just don't permit anything to coexist," Moore says. "The density of the stands is incredible. The stems can be a half-inch apart, and that's on a plant that's 15 feet tall."

In addition to trampling native diversity, broom also heightens wildfire concerns because it forms vast thickets loaded with highly flammable resins and incendiary deadwood. Its seeds survive for decades and the plants live for roughly 15 years.

"It's a serious and sobering prospect to control broom," Moore says.

Like broom, German ivy behaves like something out of a tawdry science fiction flick. "You can pull it out, but if you don't get every piece of root out of the ground, it will come right back," Thomas says. "If you accidentally leave a piece behind on the ground, it will re-root itself."

German ivy generally concentrates around rivers and creeks. According to Thomas, it is a relative newcomer, but is also showing a pretty nasty potential to strike hard, fast and wide. The worst-case scenario? "It could invade most of the mild-climate riparian corridors in the peninsula regions and beyond," he says.

Sea Monsters

INVASIVE PLANTS fall roughly into two categories: those that flourish primarily on disturbed ground--road cuts, recreational paths, fire trails, eroded areas, etc.--and those that spread as far and wide as their own limitations allow.

"Most invasive plant species are somewhat dependent on at least initial disturbance to become established," Moore says. "Once they're established, then that disturbance may or may not be a continuing requirement for the spread of the colony." And the worst of them spread like biological wildfire.

The same goes for a number of marine invasive organisms. A report prepared last year for the U.S. Fish and Wildlife Service declares the San Francisco Bay-Delta region the 'most invaded aquatic ecosystem in North America." The report identifies more than 200 exotic organisms and says that in some areas, "it is difficult to find any native species in abundance."

Invader species, the report concludes, "have contributed to the extinction of California freshwater fish and are now strongly contributing to the further demise of endangered marsh birds and mammals."

According to the Estuary Institute's Cohen, who co-authored the report, one new organism invades Bay Area waters approximately every 12 weeks.

"That's about three times the rate we had prior to 1970," he says. "It's all part of the internationalization of commerce and travel, as well as the total lack of regulation in terms of trying to prevent the movement of these organisms."

Japanese moon jellyfish, Chinese mitten crab and the European green crab are some of the South Bay's most notorious marine invasives, many of which disrupt and weaken the local food chain by feeding on the larvae of oysters, mussels and clams, and also by eating algae and invertebrates that are a marine ecosystem's lifeblood.

The green crab--first found on the West Coast near Redwood City seven years ago--has moved steadily northward and is now fouling Sonoma County's Bodega Bay.

Cohen says lagoons, estuaries and other aquatic enclaves in the South Bay are under full-tilt assault.

"I could list 20 to 30 exotic species for any of these sites," he says. "Many of them have taken over substantial portions of the ecosystem."

Amidst the recent launching of new legislative flotilla--more than 30 proposed state laws that aspire to address a spectrum of coastal environmental concerns--none of the bills specifically address the marine exotics problem.

"We've spent so much time focusing on water quality, fisheries issues and coastal management that exotics have almost slipped through the cracks, at least regarding this legislative flotilla," says Vicki Nichols, executive director of Santa Cruz chapter of Save Our Shores.

The Iceplant Cometh

THE CATALYSTS behind invasive species are manifold and complex. Most nonnative marine organisms travel the globe in ship ballast--water that is carried for weight and dumped at destination ports. Many invasive insects migrate in reaction to changes in their own native ecosystems, coaxed by changing climate patterns or simply encouraged by Darwinian opportunism.

European beach grass was imported to the California coast because it was thought to be a nifty natural mechanism for stabilizing dunes. Nope.

'It stabilizes the sand dunes so well that it changes the way they're formed along the West Coast, and wipes out native species in the process," Moore says.

The ubiquitous iceplant, a Caltrans favorite, is another exotic that has escaped control of its sponsors. Iceplant, Howald says, has minimal food value for wildlife. When eaten, however, its seeds receive a sort of intestinal Miracle-Gro treatment. These fertilized seeds are then deposited in new environments--such as dunes--that are easily conquered.

Meanwhile, the most noxious exotic plants are doing brisk business at your local nursery.

"With the possible exception of German ivy and European beach grass," Moore says, "all of the invasive species we're fighting are still sold in nurseries. You can get French broom right in the parking lot at Kmart. And every one of those plants has the potential to be an escapee into the wild. It's very disconcerting."

On a national level, government agencies spend billions fighting an estimated 4,500 invasive species. Last year's Invasive Species Act authorizes $29 million annually for controlling exotics, with an emphasis on aquatic organisms that foul industrial and municipal infrastructures. Unfortunately, it will probably take much more than that to wage an effective and unified war against these aliens.

Conservationists and concerned agencies now fight the collective invasion with a vast network of counteroffensives. The state Department of Fish and Game traps and kills red foxes in a controversial eradication effort. Ballast-water technologies and reforms aspire to curb the impact of marine intruders. Biologists introduce and even genetically enhance exotic predators to bring the hammer down on rampant species.

As for invasive plants, volunteer-powered, hand-to-hand combat may ultimately represent the survival of our natural wildland legacy.

Moore says the Wildlands Restoration Team targets nearly a dozen nonnative plants that have established a serious foothold in local state parks.

Started as a "casual, one-man vendetta against invasive exotics," the project now boasts teams of weekend volunteers who maintain 347 work sites throughout the region's state parks.

Each targeted plant requires a different response, Moore says. "With German ivy, you pretty much have to eliminate all living things on the site," he says. "We call it our scorched-earth policy. And it's very unpleasant."

Thankfully, he says, the vigorous riparian habitat regenerates quickly and the native plants reestablish dominance.

Know The Natives

ULTIMATELY, conservationists say, heightened public awareness is essential to winning the battle against exotic species..

"These organisms displace native species and thereby reduce the planet's overall biological diversity," Moore says. "In turn, this creates a much more functionally and aesthetically impoverished planet. We have a lot to lose, and we need to recognize that."

If we don't, will the invaders eventually transform us into a desiccated alien world conquered by a clique of biological opportunists, an organic wasteland teeming with rats, cockroaches and starthistle? Sure, it sounds like a bad movie. But have you noticed how fast German ivy grows?

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From the May 1-7, 1997 issue of Metro

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