I’ve heard that eucalyptus trees are a major contributor to wildfires and forest fires because they burn more easily. Is this true that they’re more flammable than lots of other types of tree? And if so, why?
The eucalyptus tree, native to Australia and now common in other parts of the world, is an exotic-looking and aromatic tree.
But in addition to looking and smelling wonderful, they’re also often regarded as potential fire disasters waiting to happen. Because of this, many in the firefighting industry and government would prefer they were just all cut down and disposed of — particularly in California.
But is the eucalyptus’ reputation as a firebomb deserved? Read on.
The tree truth
The oil that generates that lovely eucalyptus smell is unfortunately also the catalyst for a major fire event, as eucalyptus oil is highly flammable and ignited trees have even been known to explode. On hot days, the oil will vaporize and rise above the treetops, creating a highly flammable vapor that will give a fire an easy way to travel across the canopy of branches.
This leads to an accumulation of very dry, highly combustible fuel on the ground. As such, densely populated eucalyptus groves are susceptible to firestorms of incredible proportions, as presciently pointed out in this study of eucalyptus around the Berkeley-Oakland Hills area, authored 18 years before the catastrophic Oakland fires of 1991. In fact, it has been pointed out that eucalyptus was responsible for an estimated 70% of all energy released in the 1991 Oakland hills fires.
Don’t panic
Now, before you run out and chop down the tree in your backyard, let me inject a bit of sanity to reduce the paranoia.
In most cases, the particular species giving all of eucalyptus a bad name for fires is the Blue Gum Eucalyptus. Its cousin, the Red Gum, is much more fire-resistant and lacks the tendency to explode.
If you do have a eucalyptus tree on your property, there are several things you can do to reduce your fire risk. For starters, pick up the debris it drops, such as branches and leaves. Dried out, these are explosively flammable. Also, keep your tree trimmed so that it is not in a position to constantly drop dead branches, so it isn’t hanging over your house like the sword of Damocles.
If you live near a large grove of trees that are not under your control, the best thing you can be is aware of the fact that they are there. If it’s a neighbor, politely suggest the abatement steps listed above, if they don’t already practice them. If it’s public land, contact the local parks department and ask if there’s a clean up program in place to pick up eucalyptus debris.
One other alternative is to find a family of koalas to help out. These cute and furry little Aussies pretty much live on a diet of eucalyptus leaves.
Eucalyptus tree photo by NJ Price / Koala photo by Arnaud Gaillard
Fuel for debate
But in addition to looking and smelling wonderful, they’re also often regarded as potential fire disasters waiting to happen. Because of this, many in the firefighting industry and government would prefer they were just all cut down and disposed of — particularly in California.
But is the eucalyptus’ reputation as a firebomb deserved? Read on.
The tree truth
The oil that generates that lovely eucalyptus smell is unfortunately also the catalyst for a major fire event, as eucalyptus oil is highly flammable and ignited trees have even been known to explode. On hot days, the oil will vaporize and rise above the treetops, creating a highly flammable vapor that will give a fire an easy way to travel across the canopy of branches.
An additional problems is the litter of dead leaves and branches the eucalyptus tends to drop around itself. Due to the high oil and phenolic content of the debris, it cannot be broken down by fungi like many other trees’ litter. (This is partly explained by the fact that eucalyptus oil is known for its antibacterial, antimicrobial, anti-inflammatory and analgesic qualities.)
This leads to an accumulation of very dry, highly combustible fuel on the ground. As such, densely populated eucalyptus groves are susceptible to firestorms of incredible proportions, as presciently pointed out in this study of eucalyptus around the Berkeley-Oakland Hills area, authored 18 years before the catastrophic Oakland fires of 1991. In fact, it has been pointed out that eucalyptus was responsible for an estimated 70% of all energy released in the 1991 Oakland hills fires.
Don’t panic
Now, before you run out and chop down the tree in your backyard, let me inject a bit of sanity to reduce the paranoia.
In most cases, the particular species giving all of eucalyptus a bad name for fires is the Blue Gum Eucalyptus. Its cousin, the Red Gum, is much more fire-resistant and lacks the tendency to explode.
If you live near a large grove of trees that are not under your control, the best thing you can be is aware of the fact that they are there. If it’s a neighbor, politely suggest the abatement steps listed above, if they don’t already practice them. If it’s public land, contact the local parks department and ask if there’s a clean up program in place to pick up eucalyptus debris.
One other alternative is to find a family of koalas to help out. These cute and furry little Aussies pretty much live on a diet of eucalyptus leaves.
Eucalyptus tree photo by NJ Price / Koala photo by Arnaud Gaillard
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