BOTANISTS ASSESS WILDFIRE DAMAGE
DAVENPORT >> Beneath a stand of badly burned Monterey pines tucked behind the coastal prairies that line Highway 1, Todd Keeler-Wolf slid down a steep, ashen hillside cradling something in his hand.
Arriving at the base of the hill with binoculars, a camera and a rangefinder swinging from his neck, he opened his soot- covered palm and showed his younger colleagues a couple of Monterey pine seeds, unharmed except for their lightly toasted wingtips.
“These seeds rained down recently when the ground was still pretty hot,” said Keeler-Wolf, a retired vegetation ecologist, who explained that Monterey pines release their seeds after fires when plants that compete for light and water have burned away.
In the wake of the late summer wildfires that tore across California, Keeler-Wolf assembled a team of enthusiastic botanists from UC Santa Cruz’s Arboretum and Botanic Garden to conduct one of the only postfire assessments in the state aimed at evaluating how the Golden State’s different plant communities respond to varying levels of burn severity.
By trudging through burn scars in the Santa Cruz Mountains, Point Reyes National Seashore and Mendocino National Forest, the team hopes to learn precisely how the wildfires burned the land and how the damage will influence future generations of plants.
“Each forest stand has different species, different properties, different fuels, different flammability, different fire cycles,” Keeler-Wolf said. He said he believes it’s impossible to accurately measure the severity of a fire without getting your hands dirty in the field and paying attention to the stories plants tell.
“Todd’s work is great because typical fire assessments are more about fuel loads and less about species — and they’re certainly not about how these plant communities are changing,” said Lorraine Parsons, a vegetation ecologist at the Point Reyes National Seashore who is not currently involved in the project.
Last Monday, the scorched hillside overlooking the highway north of Davenport was the team’s first assessment plot of the day.
Tori Bauman, an undergraduate intern at the arboretum, began by pushing white flags into the ground in a 25-meter-wide circle. Bauman and Keeler-Wolf then poked around in the duff, the decaying vegetation on the forest floor.
They examined the tiny sprouts of poison oak and blackberries whose reddish green leaves stood out against the charred soil. They called out findings to Lucy Ferneyhough, the arboretum’s native plant project manager, who took notes on a clipboard and made her own observations. The group examined dead branches and new growth, checking for fallen seeds and digging their hands into the soil in search of clues.
Alex Hubner, a native plant specialist at the arboretum, pulled a chunk of soil out from under a carpet of flame-roasted pine needles. Instead of the chocolate brown you’d expect healthy soil to be, his dirt clod was a pale peachy- orange and let out a metallic clinking sound when he tapped it.
The dirt had been vitrified, literally turned into glass, much like how a kiln turns clay into ceramic dishes. “What we can say from this is that the fire stuck around here for a while,” Hubner explained. “It burned hot and it burned long enough to completely remove any organic matter and chemically alter the soil.”
Because the scientists couldn’t be there when the fires burned, they rely on evidence like baked dirt and freshly fallen seeds to determine exactly how ferocious the blaze was as it spread across the landscape. Some spots burned so hot that the only evidence of entire trees are underground tunnels where their roots had been. “It’s like someone snapped their fingers and the tree was gone,” Hubner said.
Fine details
But a wildfire isn’t typically a wall of flames that bulldozes everything in sight. Vaporized trees “will be right next to a patch of entirely unburned terrain,” Hubner said. Understanding why that happens and how different plants resist or succumb to fire offers greater insight for prescribed burns and predicting mudslides.
Hubner said he hopes that getting a more granular picture of how an ecosystem burns will help land managers and researchers know what to expect as they shift their st ewa rd ship pra c t ic e s away from fire suppression. Repeated mild burns, he said, prove helpful in controlling invasive species and promoting a diverse understory, the layer of vegetation beneath a forest’s main canopy.
While Hubner examined tiny seeds under a magnifying loupe he keeps on a chain around his neck, others in the group of eight excitedly shared their plant discoveries, calling out Latin names such as Toxicodendron diversilobum (Pacific poison oak) and Baccharis pilularis (coyote brush).
When the team members finished its analysis of the Monterey pine stand, members jumped into their Toyota Tacomas and drove deeper inland along a bumpy dirt road.
Keeler- Wolf, 69, exchanged witty jokes with the other self-proclaimed “old guys” on the trip: Brett Hall, the 65-year- old director of the arboretum’s native plant program, and Jim West, a 76-year- old self-taught botany savant who knows the Santa Cruz Mountains like the back of his hand.
Lifelong professionals but volunteers on this project, the senior scientists shared a wealth of knowledge and an appreciation for learning opportunities. Each of them frequently stopped what they were doing to examine the fine details of a rare species or relay interesting tidbits to the younger researchers, who listened closely, asked questions and absorbed the new information.
“I’m actually feeling quite good about the young people coming up into the world of ecology,” Keeler-Wolf said. “It makes us old guys feel like it’s worth it.”
After eating a quick lunch while standing around a box of pine cones that West had collected for Ferneyhough’s studies, the team drove onward to the last assessment spot.
On the meander ing walk through sedge prairies and manzanita scrub, West explained that more than 200 plant species could be found within 1,000 feet of where they stood. “Diversity equals flexibility equals multiple options to any given problem,” he quipped, pointing his finger in the air.
Flexibility
Nothing says f lex ibility in the face of fire like coastal redwoods. If their flame-resistant bark doesn’t save their trunk and branches from wildfire, they can resprout from surviving roots and burls below ground. The team is confident the torched trees in nearby Big Basin Redwoods State Park will recover, though it may take decades or centuries for the sprouts to grow into trees again.
“Every single plant has some way of dealing with fire, whether it’s capable of resprouting or not,” Hubner said. “And so far, we’ve found that just about everything that resprouts has resprouted already.”
Some species appear to be sprouting here for the first time in recorded history. Often called “fire followers,” some species of wildflowers, including the sweet- scented phacelia, have never been seen in the Santa Cruz Mountains until now, Hall said. “There’s a lot of things that come up after a fire and then we don’t see them again until the next fire,” he added.
Unfortunately, it’s not just rare native plants that take advantage of the cleared under-stories and pulse of nutrients that fires provide. In heavily burned spots where the slate has been wiped clean, invasive species can swiftly take over, outcompeting native grasses, wildflowers and saplings.
The younger botanists, however, expressed optimism for the future of the burned forests, their faith in the inherent wisdom of plants made stronger through studying fire’s consequences.
“Seeing the plants cleared out and coming back so immediately is pretty cool,” Ferneyhough said. “Maybe we have a chance now to maintain the land in a way that’s less dangerous to humans.”
Hubner agreed, noting that people may have a thing or two to learn from the plants his team is studying.
The plants “know what to do with fire,” he said. “We are the ones who need to figure out how to exist here. We’re still trying to understand our relationship with fire. But the plants have already figured that out.”