Joy Riders Threaten Delicate El Segundo Nature Preserve : Ecology: Vandals may destroy the habitat of the endangered blue butterfly that lives in the dunes near LAX, environmentalists say.

If the largest remaining site of coastal dunes in Southern California is hard to find, it isn’t because it’s remote.

In the shadow of Los Angeles International Airport, the El Segundo Dunes Blue Butterfly Nature Preserve is home to 11 threatened varieties of flora and fauna, including its endangered namesake.

But in the eight years since it was established, the 200-acre preserve has also become the target of a troubling breed of vandal: late-night joy riders on all-terrain vehicles who have repeatedly savaged the delicate landscape.

The latest incident 10 days ago caused environmentalists to express fear for the future of the fragile ecosystem and prompted Los Angeles City Councilwoman Ruth Galanter to criticize the security provided by the Department of Airports, which owns the property.

Authorities say a vandal or vandals used heavy bolt cutters to enter a little-used gate, then plowed through several of the highest dunes, seriously damaging plants and seedlings considered vital to the rare butterfly’s survival.

The preserve, on a narrow coastal strip at the end of the airport’s runways, is home to most of the estimated 5,000 El Segundo blue butterflies known to exist. Much of the area was cleared of houses when LAX was built in the early 1960s.

The butterfly’s survival depends almost entirely on the delicate coastal buckwheat, which butterfly pupa depend on for nectar. Officials said the fragile plant was among the most heavily damaged by the incident.

“It’s really tragic,” said Irena Mendez, project scientist at the preserve. “When you kill one of these plants, you effectively kill the butterflies.”

It was the third time in eight months that trespassers on all-terrain vehicles, commonly called ATVs, have entered the state-funded preserve, and the fifth such incident in five years, said Adriano Mattoni, its chief restoration specialist.

In the worst incident last November, vandals caused an estimated $25,000 damage to equipment, seedlings and habitat, scattering thousands of seeds that Mattoni had hoped to use for the next planting season.

Galanter, who played a key role in designating the dunes as a protected area and securing restoration funds, expressed outrage over the incident.

“Not only have these idiots severely damaged an environmentally sensitive area, but they have destroyed the work of hundreds of concerned people,” she said.

The councilwoman was especially critical of the Department of Airports, saying the incident “reflects very poorly” on its efforts to provide security.

The Federal Aviation Administration has several important pieces of navigational equipment at the preserve, including a transmitter that enables aircraft to lock in on the airport from as far as 300 miles.

Galanter said that, besides the environmental damage, the incidents raise questions about the Department of Airport’s ability to protect the navigational equipment, which she said “poses a threat to millions of passengers flying in and out of LAX.”

A spokeswoman for the Department of Airports said that airport police have stepped up patrols of the preserve and intend to assess what additional measures may be taken to prevent similar incidents in the future.

Spokeswoman Cora Fossett said that the department’s general manager, John Driscoll, and Galanter intend to meet Monday to discuss the problem.

“We are as distraught as anyone when these things occur,” Fossett said, adding that the department is “eager and willing to formulate any new security strategies that may be needed.”