Twice burned, Sonoma County’s Pepperwood Preserve has long-term stake in wildfire science and recovery

Brittle, blackened leaves on a small bay laurel tree remain frozen just as they were ruffled by the hot north wind of the Kincade fire that stormed Pepperwood Preserve three weeks ago, scorching the 3,200-acre property in the Mayacamas Mountains for the second time in three years.

Nearby, in Hendley Flat at the north end of the sprawling preserve, the shattered 20-foot stump of a venerable “grandmother” valley oak tree stands among downed limbs, another remnant of the massive blaze that scorched 60% of the property dedicated to conservation and education.

“I actually cried over this tree,” said Michelle Halbur, the preserve ecologist, noting that coyote pups had been spotted within the tree’s base, hollowed out by an earlier fire.

Nearly half of Pepperwood, some 1,658 acres, was scarred by both the Tubbs fire in 2017 and Kincade blaze, snuffed out last week after burning for 13 days, destroying 174 homes and covering 120 square miles, becoming the largest fire in Sonoma County history.

The fires’ one-two punch have cost Pepperwood more than $5 ?million in rebuilding and restoration work. But they also have further positioned the preserve as a leader in the science of wildfire recovery, with the unique opportunity to document the consequences of repetitive fires and climate change on California’s wildlands.

Already, a Sonoma State University team is at work using lidar, a laser-based measurement system, to determine how much fire fuel remains at Pepperwood, and researchers have identified more than 6,000 trees for long-term study of how the woodlands evolve over time.

A deployment of Cal Fire dozers stopped the Kincade fire on a Pepperwood ridge, and preserve staffers are now racing to repair 15 miles of tracks scraped bare by the 45,000-pound machines before the winter rains arrive.

With hand tools and a tractor, workers led by preserve manager Michael Gillogly are smoothing over the tracks that cover about 22 acres, as wide as a two-lane road in some places. About a mile had been restored Friday, he said, with volunteers and a contract crew soon to join the effort.

A few sprinkles of rain now would be a boon, triggering regrowth of grasses on bare dirt, but substantial rain would create gullies in the dozer lines, carrying sediment into creeks that feed the Russian River and support imperiled salmon and steelhead runs.

“Dozer tracks are more devastating ecologically than the fire,” Halbur said.

Rain will eventually restore the preserve’s 900 acres of grasslands, she said, and most trees - even those burned twice since 2017 - will survive in a landscape that evolved with wildfire.

“A lot of native plants do just fine with fire,” Gillogly said. “When we get rain they will spring right back.” Even trees that die serve a purpose, opening up the forest canopy to let more sunlight reach the ground, he said.

Lisa Micheli, president of the nonprofit foundation that operates Pepperwood, said the firebreaks cut by Cal Fire dozers were critical to containing the Kincade. On the pivotal night of the firefight, Oct. 27, winds at Pepperwood were recorded at up to 60 mph.

The preserve’s open space served as a battleground for stopping the blaze that roared in at night, when no Cal Fire aircraft could operate, she said, calling the scenic lands devoted to science a “tactical location” for firefighters.

Ben Nicholls, division chief ?of Cal Fire’s Sonoma-Lake-?Napa Unit, said dozer lines cut in Pepperwood stopped the fire on the preserve, keeping it out of the Mark West drainage.

“It was a huge win that we were able to hold it there,” he said, preventing a repeat of the Tubbs fire’s rampage down the drainage into Larkfield and northeast Santa Rosa.

Ten additional fire engines also were dispatched to the Pepperwood area to keep the fire from coming over a strategic ridge, he said.

Chad Costa, a Petaluma Fire battalion chief who managed the area from Calistoga to Larkfield, said the roads and grazed land in the preserve allowed dozers and engine crews to halt the fire’s southern front.

Kim Sone, a Cal Fire division chief and a forester, said the agency’s erosion control work started at Pepperwood as soon as the fire was contained Nov. 6, using some of the same dozers that forged firebreaks. Cal Fire reports said up to 67 dozers were committed to the Kincade fire, which began Oct. 23 near a malfunctioning PG&E transmission tower close to The Geysers geothermal field in northern Sonoma County.

Dozers built berms to divert water off the bare tracks and pushed dirt out of streambeds, while brush, gravel and straw wattles were also applied to curb erosion, Sone said.

Cal Fire makes repairs on public and private land at state expense, she said.

Gillogly said he appreciated Cal Fire’s work, but the large dozers could do only so much in four days. Pepperwood workers are smoothing out berms to ensure the grass seeds they hold germinate and cover the bare earth and prevent sediment from reaching the creeks.

“There’s a lot more for us to do,” he said.

Pepperwood’s forests and grasslands are home to 750 varieties of native plants and 150 wildlife species, including black bears, mountain lions, bobcats, coyotes, foxes and blacktail deer and the headwaters of three creeks that flow into the Russian River.

An acrid odor pervades the charred portion of the preserve, with black earth dotted by patches of gray ash where trees damaged or killed by the Tubbs fire burned to the ground, in some places leaving a hole where the stump would have been.

“Don’t go there,” Halbur cautioned, noting that tree roots can smolder underground for weeks.

Along Martin Creek, now a dry rocky bed in the preserve’s northwest corner, smoke rose from roots and stumps, including one stump about 6 feet tall.

“If that burns a nice cavity, it’s a habitat for wildlife,” she said.

Parts of the once mighty grandmother oak lay on the ground, riddled with small, empty holes drilled into the bark by acorn woodpeckers to hold their preferred food. The small black and white birds with red caps were busy collecting acorns from coast live oaks and flying them - under a PG&E transmission line - to a row of blue oaks forming their new granary.

Hawks, kites, harriers and other raptors were feasting on their prey, the mice, lizards and snakes that hid from the fire in their burrows but emerged without grassy cover from their sharp-eyed predators.

The human restoration work includes spreading native grass seeds over the bare, disturbed ground made vulnerable to nonnative invasive species, Halbur said.

The Tubbs fire, which covered 90% of Pepperwood, did far greater harm, destroying two homes and a barn. Two replacement structures, under construction with fire-resilient materials at a cost of $5 million, were spared by the Kincade fire.

Costs from the Kincade fire, totaling about $200,000, include erosion control work, road and culvert repairs and replacement of the scientific equipment, including wildlife cameras, positioned around the preserve.

The Tubbs fire left a lot of dead, standing Douglas fir saplings rendered more flammable by the seasons, and some remain in the wake of the Kincade fire, Micheli said.

There’s a “very low probability” the preserve could burn again soon, she said, “but we can’t rule it out.”

The series of megafires and onslaught of climate change are combining to transform Pepperwood’s landscape, Micheli said.

“We expect a trend toward more drought- and fire-tolerant species,” she said. There are 54 long-term forest monitoring stations tracking more than 6,000 ?trees to document the future of the preserve’s roughly 2,000 ?acres of woodlands.

Forests may ultimately yield to chaparral, a shrub-dominated plant community that covers only some 225 acres at Pepperwood but was far more prevalent throughout Sonoma County when Europeans arrived, Micheli said.

“Fire opens up space for new organisms and species to move in,” she said. “This is very, very exciting to us.”

You can reach Staff Writer Guy Kovner at 707-521-5457 or guy.kovner@pressdemocrat.com. On Twitter @guykovner.