Natural firebreaks:
Welltended vineyards offer natural barrier
Vineyards have slowed or halted the spread of the wildfire, saving structures.
While the Kincade Fire raged through the Alexander Valley on Thursday, Ken Wilson waited anxiously to learn the fate of two wineries and a ranch he owns in the famed winegrowing region.
Early Sunday morning, Wilson received devastating news: Soda Rock Winery, which he and his wife Diane have owned for 19 years, had been reduced to ash.
But at Wilson’s other Alexander Valley winery, deLorimier, something amazing had happened.
“The fire burned right to the edge of the winery,” said Wilson, who had gone to deLorimier on Friday to assess Kincade’s initial damage. “Just all the way to the front driveway.”
Wilson knew the reason it did not spread further — his grapevines.
“Basically, it burned to the vineyards and then stopped,” he said. “The vineyards did a good job of stopping the advance of the fire.”
He was observing a phenomenon that other vintners throughout California have been witnessing repeatedly over the past few years: Grapevines are natural fire breaks. And though they are not capable of stopping a fire like Kincade in its tracks, they may be saving struc
tures and even lives.
“The vineyards — if the vines are well kept and if they’re not letting grass grow underneath the vines — have been helping us as fire breaks,” said Cal Fire deputy chief Scott McLean. “It’s not night and day. Keep in mind these fires have seen dramatically strong winds. But we can definitely fight fire off of these vineyards, using them as anchor points.”
What is it about vines that helps combat fire?
“Vines are green and full of water,” said S. Kaan Kurtural, UC Davis professor of viticulture and oenology. “With the amount of water they can hold in their tissue, they become an oasis in a hot environment.”
Sounds simple enough. But if all it takes to stop a fire is a living plant, then why don’t trees do the trick?
“Forests have a lot of underbrush, so there’s a lot of fuel for a fire underneath the canopies,” Kurtural said.
Vineyards, by contrast, are well manicured. Aggressive pruning and leaf trimming regimens remove extraneous vegetation. By the time wildfire season hits, most grape growers have tilled their cover crop — the beneficial plants, such as rye and barley, that grow between rows of grapevines — which removes yet another burn risk.
Unlike forests, most vineyards are irrigated regularly, keeping that inner tissue moist. By the time the Kincade Fire hit Alexander Valley, most of the region’s grapes had recently been picked. Farmers usually give their vines a big irrigation drip after harvest, so the valley was likely full of wellsated vines.
The layout of vineyards also helps. The typical California vineyard is densely planted and relatively uniform, acting like an infantry in tight, close formation. It’s hard for a fire to break through that army of standing water.
“In this case, the monoculture is what makes them special,” Kurtural said.
So far, vineyards have seemed to be microbreaks, not macrobreaks. They may save individual structures, but they seem unlikely to change the overall course of a large wildfire. And they’re helpless to defend when fires jump — which happens when wind carries burning material beyond the main fire, igniting a spot fire. That was the case with the Kincade Fire, which jumped early Sunday morning to the west side of Highway 128, where it met Soda Rock.
“We take everything into account when we’re fighting these wildfires,” said McLean. “Natural boundaries, natural borders, natural defenses. A vineyard is one less thing that burns.”
Can vines ever burn? It’s possible but, according to Kurtural, unlikely. What does burn are the plastic irrigation lines, which hang near the base of vines. A vine would have to be exposed to heat for a very long period of time in order to desiccate and burn, and fires often move too fast for that to happen.
Kurtural suspects that vines’ firefighting capacity may be enhanced as these natural disasters occur.
“We’ve taken a lot of measurements of vines during these wildfires,” finding that the plants sometimes cease to perform photosynthesis due to the excess carbon in the air and the lack of sunlight from prolonged smoke, he said.
“They certainly are confused, and they can’t photosynthesize. So all the water stays in the tissue,” Kurtural said. “That might be one of the reasons they’re so good at stopping the fires.”