Fire’s return to Sonoma Valley marks growing effort to use flames to aid ecology, reduce risk

A large plume of smoke that rose above an oak-studded hillside in Glen Ellen on Friday marked the return of flames to a part of Sonoma Valley that was badly burned and is still recovering from the destructive Nuns fire of 2017.

But the fire that spread across sloping grasslands and oak savanna at Bouverie Preserve this time around was small and intentionally set, with the aim of restoring ecological balance and reducing fire risk.

Yellow-clad firefighters torched the land in staggered lines — bright orange walls of flame rising quickly, fiercely, amid loud snaps and crackles in the tall dry grass, before dying down just as fast, leaving blackened ground and dark smoke behind.

Charred Douglas fir and knobcone pine stood as eerie sentinels on a ridgeline blasted by the Nuns fire two years ago. But the blue oaks and live oaks at lower elevations demonstrated the fire resilience for which they are known. On Friday, they showed no ill effects as crews burned light, flashy grasses around some of them.

“These oaks can take a lot,” said Brian Peterson, a fire ecologist with Audubon Canyon Ranch, owner of 535-acre Bouverie Preserve.

The controlled burn comes amid growing interest and improved understanding of fire’s historic presence in California’s semi-arid landscapes —a force long harnessed by native people, but largely barred over the past century to the detriment of both ecological health and public safety.

Now, organizations including Audubon Canyon Ranch are turning back to fire as a land management technique and defensive tactic against the escalating threat of extreme wildfires like the those that swept over nearly 140 square miles of Sonoma County in October 2017, killing 24 people and destroying more than 5,300 homes.

The less-intense more frequent and controlled introduction of flames allows fire-adapted plants to reproduce and thrive, suppresses certain invasive species and reduces dead and dry vegetation that can fuel wildfires, experts say.

Local land managers have started slowly, with projects on the properties they control. But they’re building the capacity to broaden the effort to include individual property owners, said Sasha Berleman, who called the shots during Friday’s fire as consulting director for Audubon Canyon Ranch’s Fire Forward program.

“The only way to better tackle this is on this landscape scale,” said Tony Nelson, Sonoma Valley program manager for the Sonoma Land Trust.

A key initiative is the new Sonoma Valley Wildlands Collaborative, through which six public agencies and conservation organizations that manage 18,000 acres across 11 different sites in Sonoma Valley have agreed to work together on prescribed fire and vegetation management in conjunction with Cal Fire in hopes of providing a buffer against the next big wildfire.

Members include Audubon Canyon Ranch, Sonoma Land Trust, California State Parks, the Sonoma County Agricultural Preservation and Open Space District, Sonoma County Regional Parks and Sonoma Mountain Ranch Preservation Foundation.

Though conceived some years ago, the collaborative did not come to fruition until after the Nuns fire, which in 2017 burned through 56,556 acres of largely steep terrain around the valley as wildfire exploded around the region incinerating large swaths of open space, including state and county park lands.

“We’re really excited about being a part of the collaborative — that bigger picture perspective that models how we can better protect the Sonoma Valley and protect these 18,000 acres,” Berleman said. “It’s a really exciting project.”