Rebuilding Sonoma County: Revival underway at fire-ravaged Pepperwood Preserve

From a hilltop in the Mayacamas Mountains, the view is spectacular.

Massive Mount St. Helena looms to the east; the Santa Rosa Plain stretches for miles to the west, and the surrounding gentle hills are cloaked in tall grass mostly turned summer gold, waving in an afternoon breeze.

Green tree canopies seem to cover the more distant forests.

To a casual observer, the sprawling 3,200-acre Pepperwood Preserve, a place dedicated to conservation science and education, looks a lot like it did a year ago before the worst wildfires in California history ignited in October.

But a solitary black oak tree atop the hill attests to the impact of the wind-driven Tubbs fire that roared east from Calistoga over nearly the entire preserve en route to inflicting terror and loss of life in Santa Rosa.

“This one didn't make it,” said Ben Benson, the preserve's cultural resources coordinator, pausing to touch the gnarled black oak he considered an old friend. “Feels like a tombstone to me.”

Fire scorched 90 percent of the preserve, blackening grass, brush and trees and destroying two houses, two outbuildings and an observatory with a 19th-century brass telescope. The $9 million Dwight Center withstood the fierce flames, as it was built to do, but it took about two months to get preserve staff back at work inside the concrete walls.

Still, Lisa Micheli, president of the Pepperwood Foundation, doesn't consider the landscape damaged.

“Fire is an agent of rebirth and recovery,” she said, calling it a “critical part of the landscape.”

As soon as the preserve's woodlands were deemed safe to enter, staffers and other scientists began assessing the fire's immediate impact and devising long-term studies to inform future firefighting strategies and forest management practices.

“We didn't change our mission,” she said. “We changed our task list.”

Michael Gillogly, the preserve manager who has lived on the property for 24 years, said Pepperwood enjoyed a bumper crop of wildflowers this spring - yellow, white, blue and violet - and grasses that are now up to 6 feet high, taller than usual.

The abundance was nurtured by a “burst of nitrogen” from the ash of incinerated plants, he said.

Manzanita seeds, stored below ground, need fire to germinate. Knobcone pine trees readily burn, but the cones need heat to open and release seeds, he said.

“The plants have evolved with fire,” Gillogly said. “Ecologically, it wasn't a bad thing at all.”

Greg de Nevers, a former resident biologist at Pepperwood for 15 years, surveyed the property in April and May and identified 43 native plants he deemed “fire followers” for their propensity to spring from soil-stored seeds in the wake of fires, including four that had never been recorded on the property.

One of those, an annual herb with a small red to pink flower called Brewer's redmaids, was found in several spots, including a nearly solid 500-square-foot hilltop patch.

In his report, de Nevers said he felt “incredibly privileged to be able to witness the wonders of the natural world as the land and its inhabitants are transformed by this event.”

“Feeling the resurgence of life from the ashes inspires confidence in the resilience of the biosphere,” he said.

Benson, who is monitoring the preserve's black oaks, found mixed impacts from the fire.

“I see some that are so hideously burned that it's like a graveyard,” he said. All that's left of some black oaks is white ash on the ground, while 30 feet away another tree remains standing.

In a black oak grove near the top of Pepperwood's Redwood Canyon, Benson pointed out the blackened trunk of a slender tree, with a small branch bearing green leaves 20 feet above ground.

“It's amazing,” he said.

Black oaks are among the most fire-resistant of oaks thanks to their thick bark and deep taproot. One of nine oak species at Pepperwood, black oaks were prized by the Wappo, the people who inhabited the land going back 8,000 years, Benson said, based on dating of obsidian tools he's found there.

Overall, the black oak survival rate is higher than 50 percent, he said.

The depths of Redwood Canyon are a surreal area, Benson said, with the charred-black spikes of redwoods and huge firs towering to the sky mixed with felled trees that crashed onto the canyon walls or formed bridges across it.

“Yet high in the canopy, above the graveyard, some redwoods have green growth,” he said. “There is renewal there.”

Everyone at Pepperwood knew the place - home to 750 varieties of native plants and 150 wildlife species, including black bears, mountain lions, bobcats, coyotes, foxes and blacktail deer - was in harm's way.

The Tubbs fire, which killed 22 people and destroyed about 3,300 homes in Sonoma County, followed virtually the same path as the Hanly fire in 1964, pushed by strong winds from Calistoga to the edge of Santa Rosa. Healthy redwood trees at Pepperwood were left with black scars 40 feet up their trunks.

In 2013, Gillogly stood on an east-facing slope at Pepperwood raked by the Hanly fire and said it could happen again. “All it needs is an ignition source,” he said. “It could burn any time.”

Since the Tubbs fire, Pepperwood has become a “living laboratory” for a host of researchers, Micheli said.

The Sonoma County Water Agency paid the U.S. Geological Survey nearly $140,000 for a yearlong field study aimed at determining the risks of flooding, landslides and erosion on Pepperwood's slopes.

In particular, experts are conducting tests to determine the degree to which the fire created a “hydrophobic layer” atop the soil, a crust that would repel water, said Jay Jasperse, chief engineer and director of groundwater management for the water agency.

When winter rains come, the study intends to assess whether the fire resulted in an increased flow of surface water, he said.

Micheli, a watershed scientist, said the local research is valuable because most of what Cal Fire knows about post-fire risks comes from the Sierra and Southern California, much different ecosystems than North Coast woodlands.

Pepperwood's experts are also taking cues from an advisory council of Wappo tribal members, who still revere the preserve as their homeland.

Benson said the Wappo developed over thousands of years a “scientific knowledge of extraordinary depth and nuance.”

About twice a decade, the tribe set fires that harmlessly burned grass and brush, preserving open woodlands and lush meadows that sustained deer and elk, providing food for the Wappo and maintaining an ideal “park land environment,” Benson said.

Europeans and subsequently American settlers missed that message, suppressing wildland fires and allowing Douglas fir and other vegetation to grow densely among the oaks.

Those thickets created a massive fuel load vulnerable to fire, and expanding Douglas fir populations also cut off the oaks from sunlight, and in some cases took over former oak woodlands.

Gillogly said he has learned that “getting fire on the ground” is the key to sound forest management, where appropriate. But now, overgrown forests need to be thinned before they can be burned, and Pepperwood has found the conventional “lop and scatter” technique - cutting felled trees into pieces and leaving them in place - doesn't always pay off.

“It's basically like putting firewood on the ground,” Micheli said. Given time, the logs would decompose, but until then they are potential wildfire fuel, she said.

Pepperwood is evaluating its options, which include chipping the unwanted trees into small bits and scattering them like mulch, or burning small piles of wood to consume fuels.

“It's really an evolution in environmental science,” Micheli said. “We realize you can't just leave the land alone and have it stay ecologically healthy. People are critical to the health of the land.”

On a recent foray into Redwood Canyon, Benson said he watched a healthy young black bear run below him, across the creekbed and up the opposite slope.

“The bear's message of vitality and healing nourished my soul with hope for the future,” he said.

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