Pepperwood Preserve holds first controlled burn to fight invasive weed

Flames crackled in the dry grass and gray smoke arose over the Mayacmas Mountains on Friday as Pepperwood Preserve attempted to burn to death a weed with the unappealing name of medusahead.

Three Cal Fire engine crews were on hand to ignite - and closely monitor - a 7-acre controlled burn on a slope near the highest point in the 3,200-acre preserve, with clear views of Mount St. Helena, Fitch Mountain and even a bit of Warm Springs Dam on Lake Sonoma in the distance.

The burn was timed specifically to catch the medusahead, a purplish grass that flowers in the spring, with a tight cluster of seeds atop each stem. If the timing and behavior of the fire is right, a controlled burn can destroy 98 percent of the seeds, said Sasha Berleman, a UC Berkeley doctoral candidate in fire ecology.

“I think it did exactly what we wanted,” she said.

Michael Gillogly, the preserve manager, said it was “kind of exciting for all of us” to apply an age-old technique to cope with a contemporary nuisance. Medusahead, which grows in dense patches throughout Pepperwood’s 900 acres of grassland, is a nonnative, invasive species that tends to dominate the landscape, he said.

The cattle that graze at Pepperwood to reduce wildfire fuel won’t eat it, and medusahead eventually creates a blanket of dry thatch that covers the ground, suppressing growth of other plants and creating a “monoculture” as well as a fire hazard, Gillogly said.

Native Americans burned grasslands to promote growth of food and basket material, he noted. “Reintroducing fire to the environment is a big deal,” Gillogly said of the property’s first controlled burn since the preserve was established in 1979.

Michelle Halbur, the preserve ecologist, spent two weeks surveying the burn area to pinpoint the concentrations of medusahead and other vegetation, including Harding grass, another nonnative, invasive species with dense, spike-like flowering heads.

“I got grass seeds in my socks every day,” Halbur said.

Berleman said she was interested in seeing if the fire could diminish Harding grass by killing the roots of the perennial grass that stands 3 feet high.

Large green patches left on the otherwise charred burn area were Harding grass that may or may not have died, she said. But even if only one year’s growth of grass was eliminated, “that would be a plus,” she said.

The burn seemed to have devastated the medusahead, but Berleman said the ultimate test will come when the plant’s seeds are collected off the ground at the end of summer and planted in a greenhouse at UC Berkeley to determine how many will germinate.

Cal Fire crews conducted the burn, using drip torches to ignite the grass and patrolling the road with hand tools and three engines carrying water.

A Cal Fire bulldozer on a flatbed truck was on standby at Pepperwood in case the fire should escape from the burn area, said Megan Scheeline, a Cal Fire vegetation management forester who designed the fire plan.

“We’re working with Pepperwood to meet their ecological goals,” she said, noting that a controlled burn is also a good training exercise.

“Watch yourself. Eyes on the fire at all times,” a Cal Fire supervisor advised his crew as the flames began to spread.

You can reach Staff Writer Guy Kovner at 521-5457 or guy.kovner?@pressdemocrat.com. On Twitter ?@guykovner.