The recent fire in Lake County demonstrated just how quickly disaster can ignite on our dry California landscape. Here in the densely populated Bay Area, we’re no less vulnerable.

The 1991 fire in the Oakland hills took out more buildings than any fire in state history. Since then, local agencies have been trying to compromise on a fire mitigation strategy to keep the costly disaster from recurring. Decades later, we’re close to finalizing that plan. Among other things, it involves cutting down 5-10,000 eucalyptus trees. But, many people want the trees to stay, and there have been several lawsuits and protests to keep them standing.

As someone who grew up with the trees, it's hard to sort out the controversy. For years I’ve been running up the Wild Cat canyon trail in Berkeley. On the hill, the eucalyptus trees loom and creak. You’re subsumed by the smell of camphor and the fog. Up close the bark is literally opalescent pink and blue. These forests cluster all over the Berkeley and Oakland hills now, but should they remain?

I wasn’t around for the fire in 1991—the one that started in the Oakland hills just south of where I run. And I’m not a scientist, so I talked to Scott Stephens, Professor of Fire Science in the department of Environmental Science, Policy, and Management at UC Berkeley.

“We walked in that place for a week after the ‘91 fire it was actually incredibly sad how many places were burned up and essentially destroyed—all happening in one day,” says Stephens.

On an average day, most days of the year, Stephens says, eucalyptus is not a problem. But, when the right conditions come together at the same time, specifically, “an east wind in 90 degrees with humidities below 20— you got a problem,” he says.

Here’s how it starts. The fire begins on the ground -- the understory. Eucalyptus shed big strips of bark, you know they have that shaggy look, so the ground beneath them is littered with scraps that are basically fluffy piles of kindling. And the flames down there get so big they lick at the canopy up top where the leaves are, and because there’s so much oil on those leaves, the trees torch. The Australians call them gasoline trees. Stephens says, “you can easily get flames as tall as 60, 70, 100 feet high.”

The trees up high in the hills make the fire spread faster and farther. “When they burn they can throw embers a mile down wind,” he says. The burning scraps are actually the perfect shape for flying, like wings, so when the wind comes, they take off, with enough oil to keep them burning until they land down the hill.

“Those burning embers will get down there and they’ll actually start new fires,” says Stephens. “So it's not moving as a wave, it's moving by jumping. That's exactly what happened in the ‘91 fire.”

But, not everyone agrees with that story.

At a protest in Berkeley, people have a lot of reasons for wanting to save the Eucalyptus. Some hold up signs that are anti-Monsanto and DOW, two big agriculture businesses that sell herbicide— The same kind that would be hand painted on Eucalyptus stumps to prevent regrowth.

Activists point out that the US Government buys a billion dollars worth of herbicide from Monsanto every year. But not all the protesters here think that big agriculture money is behind the plan to chop the trees.

Jack Gescheidt, an organizer to save the trees, says honestly he’s “not so cynical to think that's what’s driving it. I really think its ideology that’s driving the plan to cut so many trees down.”

The ideology he’s talking about is the one that values native species over newer species. He says those values are not always rational. “This romantic notion that we should go back to just oaks and bays on the hillside with a few grasses—it doesn't make any fire sense, it doesn't make any ecological sense,” says Gescheidt.“It's exactly the opposite of what we want. We should have more trees.”

This native versus non-native species argument goes way back. You see, a lot of people think the eucalyptus were never supposed to be here.

Before the 1900’s there weren’t many trees on these hills, just some Oak and Bay. Then, a group of Berkeley professors started importing all kinds of non-native trees because they liked the idea of an urban forest. Then, real estate people found that planting them in the neighborhoods lured more homeowners.

The Eucalyptus has it’s own story. The ones in the east bay hills were bought from Australia for a lumber business. But it turned out that eucalyptus makes crappy wood. So the trees were never harvested. They just spread, edging out the other species competing for the land. Which is why people call them invasive.

But on both sides of this debate, one thing both Gescheidt and Stephens agree on is that there is no one right environment for these hills. As Stephens puts it: "We’ve changed ecosystems so much in this country.”

He says there were hundreds of years when the Native Americans were burning all the plants that grew on the hills in order to make room for a certain grass that flourished from the ashes. The seeds in the grass were a staple crop of theirs. But that grassland is gone. According to Stephens, the grasses we have in the East Bay now are eighty percent invasive. They came from the Spanish 300 years ago.

So, we can’t realistically return the land to the way it was before. All we can do is figure out what’s most beneficial for the land that we can control.

“You don't want to go after every species that takes over a site thinking it's always evil,” says Stephens, “the new system could provide services. So, you have to look at it one thing at a time.”

And the one thing we need to look at now is the fire hazard.

These days, when I run in the hills I’m more captivated by the Eucalyptus. In the morning the rest of the hill begins to scorch from the sun, but I look at them and they’re glistening with wetness. It’s because the Eucalyptus trees collect moisture from the fog. I head underneath the canopy and it sounds like it’s raining lightly. But, tragically, it’s not enough moisture to make the area fire proof.

Many of these plants are fire dependent. But we’ve been preventing fires here for 150 years. The fuel is just building up. So now, when I look around, I see a hillside that’s been waiting for over a century to do what it wants to do every several months: burn.