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Eradicating iceplant on California's central coast

Native plants rebound after weed remediation.

Publication date: January 25, 2012

By Leslie Drahos

Point Piedras Blancas on California's central coast, just north of San Simeon State Park, is home to an historic light station built there in 1875. The name came from Spanish explorers who used the "white rocks" off the end of the point as a maritime landmark. Piedras Blancas Light Station (PBLS) sits on a point at the southern end of Big Sur and the Santa Lucia Mountains, six miles north of the community of San Simeon.

The 19-acre parcel includes a half-mile of ocean frontage and is surrounded by a rocky shoreline that supports a diversity of marine life, including northern elephant and harbor seals, sea lions and otters, gray and humpback whales, and a variety of marine and terrestrial birds.

PBLS was operated by the U.S. Lighthouse Service until the Coast Guard assumed command in 1939. In 2001, site operations were transferred to the Department of the Interior's Bureau of Land Management (BLM).

When the BLM inherited the property, all but 15 percent of the 19-acre-site was blanketed with a thick mat of iceplant (Carpobrotus edulis) that had been planted during the Coast Guard's tenure. Iceplant was thought to control erosion, required little maintenance, and was fire resistant. The creeping succulent was introduced to California in the early 1900s from South Africa to stabilize soil along railroad tracks. It was later planted by the California Department of Transportation along coastal highways and beaches to combat sand drift and erosion.

Iceplant grows in warm climates under 500 feet in elevation, is intolerant of frost, and is not found far inland. Yet the plant has flourished along coastal highways, on military bases, and on other public and private lands. It has invaded foredune, dune scrub, coastal bluff scrub, coastal prairie, and most recently maritime chaparral communities, competing directly with threatened or endangered plants for nutrients, water, light, and space.

The BLM crafted a management plan to restore the native ecosystem that called for removal of the iceplant as well as other nonnative plants found on the Point Piedras Blancas land. The initiative required workers to avoid disturbing Native American artifacts buried in the area, protected under state and federal laws, that date back 3,000-plus years.

"When the BLM assumed management in 2001, they advertised for volunteer help," says Carole Adams, freshly retired at the time. "I was interested in preparing marine mammal training material for guides, but when I met the park manager, he said what was really needed was a booklet about nonnative plants that they wanted to get rid of. So I learned about all the plants that were growing out here. We identified 40 nonnatives growing on the light station property. The most prolific was the iceplant; it was choking out everything else."

There were two phases in the battle against iceplant. "The first was hand-pulling in areas where there were native plants surviving under and around the iceplant, an incredibly labor intensive and tremendous accomplishment on the part of volunteers. We did a lot of manual work for about four to five years," says Adams. "After that, the BLM was approved to use chemical [herbicide] spray on sections where the iceplant was so thick that it came up to our knees. We couldn't ask volunteers to pull out something that thick. The spraying was done in stages by trained BLM personnel and spread out over several years."

The herbicide glyphosate was used to kill the iceplant in areas where it grew in dense accumulations and where no native plants were present.

The pulled and sprayed iceplant was left to dry out before it was removed from the site. Then tarps, wheelbarrows, and trucks were used to haul the debris to dumpsters. "If you just leave it in a pile, it will start to grow again," says Adams.

Jim Boucher, PBLS park manager for the BLM, credits Adams as the driving force behind the restoration. She organized the whole project, identified invasive plants, mobilized volunteers, and has maintained detailed records since 2001. She also conducts an annual survey to track progress and trains volunteers to give guided tours.

"It is astonishing how quickly the entire ecosystem recovers [when invasive species are removed] and it is not just the plants that are coming back," says Adams. "We have seen tremendous increases in the number of species from insects, butterflies, and birds to small animals — voles, mice, ground squirrels, rabbits, long-tailed weasels, coyotes, and even deer, which had not been seen out here for 20 years."

The effort is ongoing as dedicated volunteers, drawn to the site for its beauty, must continue to weed out invasive plants. And the challenge has grown since the 2005 acquisition of 13 miles of coastline from the Hearst Corp. for San Simeon State Park, which abuts the PBLS property.

In 2008, PBLS was designated as an Outstanding Natural Area within the National Landscape Conservation System (NLCS), which ensures the conservation, protection, and restoration of nationally significant landscapes.

Leslie Drahos is a freelance writer in Sagamore Hills, Ohio.