The redwood trees are native to California, but I photographed them beside Canberra's airport in Australia. They are part of the legacy of Walter Burley Grifin, the American who designed the city.

[Lupine]

I'm a big fan of eucalyptus! Not a bad swap, redwoods for eucalyptus.

Sorry, eucalyptus is a terribly invasive species and a major fire hazard. The 1991 Oakland firestorm that killed 25 people and destroyed almost 4,000 home was fueled largely by eucalyptus trees. Just wave a match near a eucalyptus and it's likely to burst into flame because of the very high and very flammable oil content. Eucalyptus is a major contributor to many of the wildfires that plague California and it displaces more fire resistant native species.

Link

If I could, I would destroy every eucalyptus in North America.

[RobG]

Sorry, eucalyptus is a terribly invasive species and a major fire hazard. The 1991 Oakland firestorm that killed 25 people and destroyed almost 4,000 home was fueled largely by eucalyptus trees. Just wave a match near a eucalyptus and it's likely to burst into flame because of the very high and very flammable oil content. Eucalyptus is a major contributor to many of the wildfires that plague California and it displaces more fire resistant native species.

California Coast Pine (Pinus radiata) forests were a major contributor to the firestorm which destroyed hundreds of homes in Canberra, Australia in 2003. Pine trees are also highly flammable. Any forest in high fire danger conditions will burn, and the sad fact is that a lot of forest fires are deliberately lit, so it's not necessarily reasonable to blame the trees. Having read this link (from the comments in the same page you linked), the main causes of the Oakland fires were firestorm conditions and a failure to perform control burns prior to the fires to reduce fuel loads. The Canberra fires resulted from similar conditions - extremely low humidity, high temperatures and high winds.

[GeoJerry]

Having read this link (from the comments in the same page you linked), the main causes of the Oakland fires were firestorm conditions and a failure to perform control burns prior to the fires to reduce fuel loads.

Agreed. Another point is that California's native chaparral vegetation is notoriously flammable.

From Chapparal

"Chaparral plants are highly adapted to periodic natural fires which occur once every ten to thirty or more years.... As long as fire does not occur too frequently, it has the potential to rejuvenate chaparral by encouraging the growth of numerous species which might have been excluded in the years immediately preceding the fire."

In fact, about 20% of California's vegetation is not native to the state, having been introduced from the likes of Spanish missionaries and Gold Rush settlers.

Is the answer to remove all trees and vegetation for fear of fire? Or to replace all native vegetation with fire resistant varieties? I don't think so. I suspect Oakland's fire, and others (e.g. Malibu and Santa Barbara) would have burned with or without the presence of eucalyptus, whether significantly more slowly so that structures would have been spared is hard for me to say.

[Barnster]

Wow some nice shots but better history - what did we do before Google ? (make $hit up ha!)

No, I think of memory there was a place called a library where info like this was stored in books.

[RobG]

No, I think of memory there was a place called a library where info like this was stored in books.

And before that, people actually remembered stuff!

[Lupine]

California Coast Pine (Pinus radiata) forests were a major contributor to the firestorm which destroyed hundreds of homes in Canberra, Australia in 2003. Pine trees are also highly flammable. Any forest in high fire danger conditions will burn, and the sad fact is that a lot of forest fires are deliberately lit, so it's not necessarily reasonable to blame the trees. Having read this link (from the comments in the same page you linked), the main causes of the Oakland fires were firestorm conditions and a failure to perform control burns prior to the fires to reduce fuel loads. The Canberra fires resulted from similar conditions - extremely low humidity, high temperatures and high winds.

The causes of the Oakland Hills firestorm are fairly well established. However, I didn't blame the fire itself on the the Eucalyptus trees, I said it was fueled by them. Most resinous tree species are very flammable, including coast pines. However, eucalyptus has a characteristic that pines don't have; they have a tendency to blow up when they burn. That spreads flaming debris fire over a much larger area than a pine or oak that burns w/o blowing up. As a result, eucalyptus fueled fires can spread much quicker and over a wider area than it would have under the same conditions, but the trees had been the native redwoods, oaks and pines. Eucalyptus also 'sheds' much more heavily than native CA trees, so they generate a much greater amount of highly flammable ground debris, which also significantly increases the fuel load.

So my concern isn't that eucalyptus trees cause fires, neither they nor any other tree causes a fire to start. However, once a fire has started, eucalyptus are just about the worst possible trees to have in the fire zone.

[Lupine]

Agreed. Another point is that California's native chaparral vegetation is notoriously flammable.

From Chapparal

"Chaparral plants are highly adapted to periodic natural fires which occur once every ten to thirty or more years.... As long as fire does not occur too frequently, it has the potential to rejuvenate chaparral by encouraging the growth of numerous species which might have been excluded in the years immediately preceding the fire."

Chaparral is a native species, fire is part of it's life cycle and it does not displace other native species.

In fact, about 20% of California's vegetation is not native to the state, having been introduced from the likes of Spanish missionaries and Gold Rush settlers.

Honestly, I'm surprised it's 'only' 20%.

Is the answer to remove all trees and vegetation for fear of fire? Or to replace all native vegetation with fire resistant varieties? I don't think so.

Neither do I. However, I do think that eliminating invasive non-native species is a good idea, even if they aren't more fire prone. They displace native species and provide absolutely no benefit to the environment or people. In the case of eucalyptus, they are actually a negative, because of all the flammable debris they produce and because they displace native pines, oaks and redwoods.

I suspect Oakland's fire, and others (e.g. Malibu and Santa Barbara) would have burned with or without the presence of eucalyptus, whether significantly more slowly so that structures would have been spared is hard for me to say.

It's not hard for the experts. While they agree that they fire would have been bad under any circumstances, they also agree that eucalyptus trees aggravated the severity of the fire. Link - Claremont Canyon Conservancy

Additionally, the introduction of vegetative species that are not native to the area has dramatically impacted fuel loading. This is particularly true of the introduction of eucalyptus. Fuel accumulations in some areas under eucalyptus plantations have been estimated between 30 and 40 tons per acre. Monterey Pine was also introduced into the area and contributed significantly to the fuel loading.

Audobon Magazine Link - America's Largest Weed

Of the many eucalyptus species that evolved with fire, none is more incendiary than blue gum. "Gasoline trees," firefighters call them. Fire doesn't kill blue gums. Rather, they depend on fire to open their seedpods and clear out the competition. And they promote fire with their prolific combustible oil, copious litter, and long shreds of hanging bark designed to carry flames to the crowns. Blue gum eucalyptus doesn't just burn, it explodes, sending firebrands and seeds shooting hundreds of feet in all directions. Living next to one of these trees is like living next to a fireworks factory staffed by chain-smokers.

Just to be clear, I am well aware that native species also cause problems. Monterey pines have been introduced into a lot of areas where they aren't native either, and not surprisingly, they also cause problems, although not to the scale of eucalyptus.

[RobG]

However, eucalyptus has a characteristic that pines don't have; they have a tendency to blow up when they burn.

Interestingly, when I did a Google search on "exploding trees" one of the first articles I found (thanks to Google localising the result) was the transcript from a TV clip about the 2003 Canberra fires. The only mention of exploding trees was exploding pine trees, not eucalypts. I'm sorry, but your repetition of the "exploding tree" myth of Eucalypts without basis is annoying. The Canberra fires killed thousands of trees in Namadgi National Park, the vast majority of which are still standing. I can send you photos which I have taken myself, if you like. Many other trees died in the open fields because their crowns burned and the heat was so intense that the branches were unable to recover. If Eucalyptus trees are truly as explosive as you claim, the Canberra firestorm should have reduced the native forest (whose large trees were almost entirely eucalypt species) to an ashen wasteland with no standing trunks. It didn't. I would expect that in the heat of a firestorm, any tree which contains a lot of sap might burst apart, not simply one particular species or family. So - do some trees burst in the heat of a firestorm? Absolutely. Does every eucalyptus tree behave this way in a fire? Absolutely not. Do other species of trees suffer the same fate? Sometimes, yes. The suburb of Canberra which suffered the most in the fires was right next to a mature pine forest. Cinders from that burning forest would have caused the majority of house fires in that suburb. Should Australians demonise Californian pine trees?

My point is that the way you describe Eucalyptus trees is to make it look like each one of them is a bomb waiting to go off, which is not accurate. I also didn't post this photo of Californian Redwoods in the Pialligo forest in order to have a disagreement about bushfires and trees. I love both pine trees and eucalypts. They each have their good and bad points. I suspect we'll have to agree to disagree on their benefits and hazards.

[southlander]

I'll wade in here. In 1983, in an event known as Ash Wednesday, bushfires (wildfires to Americans) erupted in the hills immediately to the east of Adelaide. Across South Australia there were 28 deaths. This included 14 fire-fighters who died across both SA and Victoria that day. Many fatalities were as a result of firestorm conditions caused by a sudden and violent wind change in the evening which rapidly changed the direction and size of the fire front. The first day, the hills were shrouded in a thick blanket of dust driven down from Australia's interior from hot northerly winds (with a temperature of 43C (109F) that day). Because of the dust, no-one really understood just where the fires were. The second day, the hills were visible after that wind change that introduced clear air off the Southern Ocean, but also acted to turn the fires onto new paths. I was in a city high rise building both days, but on the second day, with now clear views to the east of the city (the prior day, the hills could not even be seen from the city for dust). What actually explodes is balls of combustible gas (carbon and boiled off eucalyptus oil) that forms above the tree line. Periodically, the air would reach a combustible air to fuel ratio and an upward lick of flames from the trees would set off a fireball above the treeline. I watched this happen numerous times that day.

So, in my opinion, its not the trees but gas balls above that 'explode'. In itself, this does not spread debris. Once an intense fire develops, it creates its own local weather system and thermals. This is what lifts cinders and the like into the air, and moves them forward from the fire front.

South Australia also had devastating fires in pinus radiata plantations in the southern part of the state during the same event, so I'm not on any particular tree's side here.

Bottom line, whether it is eucalyptus oil from gum trees or resins from pines, once intense fire conditions develop, both oils intensify a fire and create deadly conditions.

The underlying issue, again in my opinion, is that as suburbia, bush blocks, farmlets, whatever, encroaches on bushland/forest, natural fires that reduce the fuel load of the scrub and waste below trees tend not to occur and preventative measures such as controlled 'cool' burns in autumn or spring are not undertaken due to the complications of houses now tucked into forest and associated NIMBY issues. So, the fuel load builds for 20 year or more until an uncontrollable fire occurs and then an extremely intense fire occurs because of the fuel load that has built up. It's not any tree's fault, it's another example of man interfering with natural patterns, and then looking to shift blame back to nature when the mirage of man being master of the planet receives a setback.

[Lupine]

II'm sorry, but your repetition of the "exploding tree" myth of Eucalypts without basis is annoying.

I didn't just pull that claim out of my hat and I'll also point out that the vast majority of eucalypts in California are Blue Gums. According to what I've been able to find in my research, Blue Gums are far and away the worst of the species WRT fire and flammability.

http://firefreefitch.org/eucalyptus/
http://wwwlibrary.csustan.edu/bsantos/section3.htm
http://www.omg-facts.com/view/Facts/47929
http://www.ehow.com/list_7478176_dangers-eucalyptus-trees.html
http://www.newworldencyclopedia.org/entry/Eucalyptus

I am sorry for hijacking your thread, I confess that I do tend to over-react a little on this topic. I live just south of Oakland and have friends who live(d) in the fire zone, one of whom lost his home and another whose house is less than 200 feet from where the fire stopped. You can still see the burn line today.

[RobG]

I didn't just pull that claim out of my hat and I'll also point out that the vast majority of eucalypts in California are Blue Gums. According to what I've been able to find in my research, Blue Gums are far and away the worst of the species WRT fire and flammability.

Thanks for the links. I'm disappointed that none of them have any references to research papers - not even the University article. So I'll grant you that a number of US sources are claiming that Eucalyptus trees "explode" but I can't see any basis for the claim. I also faound claims that pine trees "exploded" in Canberra. I don't really want to continue the disagreement - my main concern which I expressed previously was that care has to be taken to avoid giving the wrong impression. It may well be that Blue Gums can sometimes burst in firestorm conditions, but having this happen to occasional trees in a firestorm is very different from giving people the impression that all Blue Gums are bombs waiting to explode at the slightest provocation. The Oakland fire report talked about the contribution of poor control of fuel in the time prior to the fires.

I am sorry for hijacking your thread, I confess that I do tend to over-react a little on this topic. I live just south of Oakland and have friends who live(d) in the fire zone, one of whom lost his home and another whose house is less than 200 feet from where the fire stopped. You can still see the burn line today.

The fires in Canberra got to the back window of my brother's apartment, went around the side and burned down the building next door. A lot of people were calling for all the pine forests in the ACT to be cut down after the firestorm. In the sort of conditions that led to the firestorm in Canberra, any sort of vegetation contributed to the spread of the fires. Spot grass fires occurred throughout the ACT. The important sorts of lessons are things like - using controlled burns in appropriate conditions to reduce fuel loads and keeping sufficient distance between forest and houses. The answer is not necessarily to blame one kind of tree. In firestorm conditions, there will be circumstances where nothing can be done, regardless of what kind of forest or vegetation is involved.