Attack of the Killer Weed

Can a hardy little moth stop the fern that wants to eat the Everglades?

It's been enough to convince even skeptics that bioagents are a real alternative to spraying. "We needed to convince the state agencies that this was a long-term alternative to chemicals," Rayamajhi says. "At the beginning, we didn't have the funding to disperse the insects, but now they've reallocated some of the chemical funds to insects."


In late 2000, John Volin, an infectiously energetic plant scientist at Florida Atlantic University, began looking at the steady growth of Old World climbing fern. Little was known about its biology. Not until 1978 was its spread scrutinized by two scientists, who found it growing near the shoreline in southern Martin and northern Palm Beach counties. They concluded that the spore-bearing plant was a cause for worry.

A sprig mug shot of Florida's Public Enemy Number One: Old World climbing fern.
Peggy Greb
A sprig mug shot of Florida's Public Enemy Number One: Old World climbing fern.
The lighter-colored foliage atop this tree island is Old World fern, which smothers the native vegetation below.
The lighter-colored foliage atop this tree island is Old World fern, which smothers the native vegetation below.

No one got worried.

The fern, however, spent the next 15 years diligently establishing itself in the undergrowth beneath trees, then climbed upward, finally coiling around branches and leaves. Starved of sunlight, the trees slowly died. The South Florida Water Management District, a state agency that's a frontline warrior against invasives, began aerial surveys of the fern in 1993 from coast to coast at 500 feet above treetops. By the end of the decade, the water district had data indicating that the fern had spread to Florida's west coast and was overwhelming the tree islands of the Loxahatchee National Wildlife Refuge in south Palm Beach County.

What, Volin wondered, was the Everglades facing?

Using the data collected between 1978 and 1999, Volin devised a computer model to project the spread of the climbing fern by the year 2014. Despite knowing how rapidly the plant had multiplied, what Volin found stunned him. The model revealed the fern covering almost all of the Everglades in Palm Beach, Broward, Hendry, and Collier counties. Substantial portions of Martin and Glades counties will be smothered, and the infestation will have made deep inroads into Everglades National Park in Miami-Dade County.

Volin's findings seemed too dire to be true. "I said, 'Hell, we can't share this,'" Volin recollects. So before announcing the findings in 2002, Volin and his research assistants double-checked the reliability of his prediction through painstaking marches through the Everglades. "I feel strongly that, as a physiological ecologist, when we're doing predictions -- whether it's about climate change or, in this case, an invading species -- you don't want to overstate it," Volin says. "It's like saying the sky is falling. You don't want to do some dire prediction only to eat your words later on."

No one's calling Volin a Chicken Little.

Don Schmitz, with the Florida Department of Environmental Protection's invasive-plant bureau, estimates that state agencies spend more than $2 million a year to combat Lygodium, about eight times more than five years ago.

The Loxahatchee Refuge recently received $4 million from Congress to fight exotics, Melvin says, and the threat of Old World fern certainly helped loosen up those purse strings for tree triage. "There will be aerial spraying of islands where there aren't any native plants left and follow up with a ground crew on the perimeter," she adds.

Volin, who possesses a bantam build, impressively full goatee, and piercing eyes, is overseeing another ambitious, yearlong project, funded by the water district, to hunt down incipient sporelings of Old Word fern in the east-central part of the Everglades. His research team will visit each of the roughly 500 islands and, using a global positioning satellite device, record each sighting of the fern. The management district will then send out contractors who will find that exact spot and treat the plant with a systemic herbicide that destroys it. It's an endeavor analogous to bicycling across the U.S. to visit every 7-Eleven: They're everywhere, and you never know where the next one will spring up. Just how much this will cost won't be known until later.


On a partly cloudy morning in late May, Volin and three other researchers haul two airboats an hour south of Davie to a public dock along Tamiami Trail. This is the driest month in the Everglades. The water covering the vast expanse of grass surrounding tree islands has slowly dropped through the desiccated winter months, and the routine rainstorms of the tropical season have yet to begin in earnest.

The airboats are relatively small three-seaters, each driven by a cacophonous 12-cylinder aircraft motor. The two boats weave northeasterly for about 20 minutes, sometimes crossing patches of slough that are little but mud. They pull up to a high stand of sawgrass on the east side of a tree island. The real work begins on foot. All dressed in long-sleeved shirts and long pants, they begin the fern hunt by stepping off into water that's just under two feet deep.

This is the first foray into the Glades for Mary Ann Furedi, a new researcher who's only recently moved down from West Virginia, where she walked mountainous terrain studying ginseng. A 20-something with longish, dark-blond hair, Furedi will head this new project, but it will go far beyond the tasks contracted for by the water district. Among other things, they'll be trying to identify "bio-indicators," which are plants or formations that act as hospitable hosts to a particular invasive species. When such a correlation is made, a bio-indicator creates a kind of shortcut for locating invasives and figuring out their reproductive and growing cycles. Melaleuca, for example, is a sucker for spots that have been disturbed by fire.

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