Yet Rice, who helped plan UC Berkeley’s portion of the FEMA application, says that factor is mitigated by the higher moisture content of bay laurel leaves. ... Wildfires burn rapidly under them and through the tree crowns. A widely grown species, silver dollar gum (Eucalyptus polyanthemos) is hardy to USDA zones 9 through 10. “We’re trying to change fire behavior,” he says, “to make it easier to put the fire out, to give people more time to evacuate.”. Here, the debate about the flammability or fire danger of an entire forest is reduced to its smallest, most arcane variables, starting with leaf chemistry. The shower of firebrands tossed from the ridgeline by the 100-foot-tall trees foils any attempt to create a firebreak. Like the other Australians I spoke with, Sullivan called the Bay Area blue gums “supersized,” treated to better soils than those in nutrient-poor Australia and untrimmed by their native pests. These hardy plants have delightfully scented, volatile oil in all parts of the plant. Andrew Sullivan, a bushfire expert at the Commonwealth Scientific and Industrial Research Organization in Canberra, says that in Australia, dry eucalypt forest might accumulate eight to 12 tons of debris per acre. That’s the idea in thinning the eucalyptus—not to prevent fire, but merely to create the possibility of keeping it from growing out of control even in those rare instances when conditions are at their worst. Although blue gums tend not to invade new territory, they are salt-the-earth occupiers: Along with shading out other species, their leaf litter leaches chemicals that suppress growth of native plants, even after the trees are removed. “This is my favorite tree,” Grassetti says, giving it a slap on the trunk. This is Gallup’s favorite part of the job, he says—choosing which trees to remove, which trees to keep. Leaves or other components, meanwhile, can tell you only so much about the whole, and individual trees only so much about the forest. The trunk can sprout new limbs and regenerate the plant unlike other types of trees, which have to re-sprout from the roots. You get away from stress, smell the smells, see the birds. The bark is a blue-grey colour and peels off in strips to reveal yellow patches underneath. Gallup considers the gum, buried in a pyre of its own debris. Many eucalyptus species are available as landscaping plants. But the frost didn’t really kill the trees, only made them retreat back down into their roots. The gums are mottled tan and brown like chicken bones, crowded together, the spaces between them choked with brush and hung with streamers of bark. So are eucalyptus trees flammable? Sign up to get all the latest gardening tips! The eucalypti grow rapidly, and many species attain great height. In the early 2000s, UC Berkeley and the nonprofit Claremont Canyon Conservancy cleared 70-odd acres on the south side of Claremont Avenue. (510) 528-8550, Subscription Customer Service: We target grass. (This is the approach that Jerry Kent predicts will cost the most, and native plant advocates say will result in a monoculture, though it is acceptable to the Hills Conservation Network.) zachstgeorge.com. It was immediately clear that the debate over the blue gum’s flammability is only one of several parallel conversations around the tree; while that is the Hills Conservation Network’s primary focus, it was not necessarily what most interested the individual protesters or their opponents. Get involved. Seasoning refers to splitting the wood soon after the tree is cut so that the wood can dry out. -Brad Gallup, EBRPD fire captain. There are some native eucalyptus but the majority have been introduced. Everything you need to know about choosing the right eucalyptus for you. Eucalyptus trees are common in California and the warmer states of the United States. But then they catch on fire.” Eucalyptus is a highly flammable tree and particularly dangerous to have in a wildfire prone areas. He has also independently researched the costs of eucalyptus removal and management. Near Anglers Rest, Victoria, Australia. Perhaps as important, Kent says, this side is cheaper. We pass through the tunnel and drive into the hills. As intriguing as the theory is, Bowman thinks it goes too far, failing the Occam’s-razor test: It’s simpler to imagine that eucalyptus evolved with oily leaves because those oils deter insects and koalas; they evolved peeling bark because the falling bark takes parasitic epiphytes with it; and the trees quickly resprout en masse after fire because they’ve evolved to tolerate fire, not to enjoy it. “Eucalyptus is highly flammable and a very dangerous tree.” Fuel reduction projects that target the nonnative trees are not new. We drive next to Signpost 29, for another view of the possible future. “We’re in our infancy in understanding how flammability can be practically measured and scaled up,” he says. Of the hundreds of species, only a few call California home. 3. “I love trees,” he says. The summer fogs have faded, and it’s been unseasonably hot for a week. From the brush down at the bottom of the gully, there is the whine of a chain saw. But it is plenty complicated on its own. > IUPAC name 1,3,3-Trimethyl-2-oxabicyclo[2,2,2]octane “They’re absolutely dangerous plants,” he says. Bay Nature connects the people of the San Francisco Bay Area to our natural  world and motivates people to solve problems with nature in mind. After a fire, many eucalypt species will sprout epicormic shoots along their entire trunks. We walk uphill along Claremont Avenue, then hike up into the eucalyptus grove. The Hills Conservation Network, a small Berkeley nonprofit whose members live in the area covered by the FEMA grant, promptly sued FEMA to stop the grant, focusing in particular on roughly 350 acres of Oakland and UC Berkeley property in Claremont Canyon and Strawberry Canyon and around the Caldecott Tunnel, where all nonnative trees—predominately eucalyptus—would be removed. “Anybody who wants to encourage really flammable plants in an urban mix has to do it with their eyes open,” David Bowman told me. This makes the tree’s oil a wonderful antibacterial, antimicrobial, and anti-inflammatory, but the unbroken down material is like using kindling to start a fire. Every story from Bay Nature magazine is the product of a team of people dedicated to connecting our readers to the world around them and increasing environmental literacy. We stop at a turnout and hike up a path through tall grass that opens into a field. They provide interesting color to flower arrangements. They simply dry up, becoming increasingly ever more flammable. Like many of the trees in this forest, it was cut after the hard frost of 1972. This summer, even without rain, some of the trails were so slushy they were nearly impassable. He is persistently neutral: “Everybody’s right, everybody’s wrong,” he says at one point. I asked her why the consortium gave blue gum a high ignitability rating as well as a high hazard rating—what studies was that based on? More bark peels from the trunks and spills out from piles built up in the valleys between them. Euc-defenders point out that the leaves of native California bay laurel trees also have a high oil content. As its shred-like bark is considered flammable, keeping this debris cleaned up is preferable. Scientists speculate that flammable eucalyptus trees evolved to be “fire friendly.” Rapidly catching fire until there is no obvious tinder allows the plant to retain most of its trunk when fire moves on to find more to burn. They do this in several ways: by sprouting from underground tubers, hidden buds under their bark and f… Even a small fire can transform to a major wildfire in eucalyptus forests, due to the huge amount of leaf litter, the oil-rich leaves on the trees, and flammable bark. The tree sheds bark and dead leaves, which make a perfect pile of tinder under the tree too. Not just any fire, but the fire, the fire that all this is about. Eucalyptus trees are widespread in California and have been introduced to many other warm states. Are Essential Oils Flammable? The main constituent of Eucalyptus oil is Eucalyptol it has a flash point of 46°C so easily burns. But now, standing by Grassetti’s favorite tree, even this most damning of blue gum statistics seems woefully abstract. One bolt of lightning or a careless cigarette and the forest can easily become an inferno. And he imagines it catching fire. “It’s an amazing just-so story,” he says of the possibility: “Eucalypts evolved to burn their neighbors.”. Their concerns echoed some of those of the 13,000 people who wrote comments on the first draft of an environmental impact statement FEMA prepared ahead of the grant. Eucalyptus pulverulenta, the silver mountain gum is loved by the florists. The ground is muddy. You get away from stress, smell the smells, see the birds. And then somehow—maybe a spark from a car, maybe a tossed cigarette—the whole dry, airy mess catches fire. “Like, you couldn’t come up with a better way to get that tree to burn.” This tree is surrounded by others just like it; this grove just one of the dozens between here and Lake Chabot, millions of blue gums billowing from the ridgeline like sage-green smoke. He is among the pro-eucalyptus faction’s star fire authorities, although his expertise, he admits, is not in wildland fire. 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