A study has found traditional fire management strategies like, hazard reduction burns, logging and thinning out forest undergrowth may actually increase the flammability of Australian bushland.
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00:00 So, what we've found is that forests that have been logged or have a history of thinning
00:06 or a history of prescribed burning actually become quite flammable for between 5 to 70
00:13 years after the disturbance.
00:15 So what we're seeing is a pulse of flammability that is triggered by the disturbance, either
00:20 be it logging, thinning or prescribed burning.
00:23 Did these results surprise you or is this something that you anticipated?
00:27 Some parts of it are surprising, but when we think about fundamental ecological principles
00:31 about how forests grow and develop, it actually makes quite strong sense.
00:37 What we see is that as forests get older, they often get more moist, they get cooler,
00:44 often darker, the microclimate is less windy, and these are some of the most fundamentally
00:50 important parts of flammability in these forests.
00:54 So there are some fundamental ecological reasons why older forests that are long undisturbed
01:00 are the least flammable.
01:02 And my understanding is, you say that prescribed burns reduce fuel loads for a period of time
01:07 and then there's that pulse in flammability.
01:09 So what if those prescribed burns were happening before the pulse?
01:13 Is that a safe way to do things with that kind of regular upkeep?
01:17 Well what the paper is really showing from a whole range of studies across Australia
01:21 and also overseas is that prescribed burning in many cases, not all, but in many cases
01:27 leads to short-term gain but long-term pain.
01:32 And that's because prescribed burning can trigger a pulse of flammability, regeneration,
01:38 regrowth of the forest, which can be flammable for many years afterwards.
01:43 And this is really quite a concern, particularly when we're burning in remote areas with large
01:48 scale industrial prescribed burns that change the forest in ways that increases the risk
01:54 of high severity fire.
01:56 And this is something that many fire chiefs have actually known.
01:59 I've had quite a bit of correspondence about this.
02:02 And for example, a senior now retired fire manager wrote to me recently and said, "You'll
02:08 be attacked for daring to question the prevailing philosophy within fire services.
02:13 But from a firefighter's perspective, what you've described, I've actually been seeing
02:19 for decades, that the more you burn, the more you have to burn.
02:23 It's the old conundrum.
02:25 If you always do what you always did, you will always get what you always got."
02:29 And I think that's really quite profound from people that were very senior in the firefighting
02:33 agencies actually recognising that what we're describing in this new paper is something
02:38 that they've known for quite some time.
02:40 I mean, the implications of this are pretty significant.
02:43 Over management of bushfire areas can be a matter of life and death.
02:47 So how important is it for fire authorities to pay attention to these findings?
02:52 Well I think it's critically important to rethink what we're doing here.
02:56 Often what we're seeing, for example in Victoria right at the moment, plans to do extensive
03:01 industrial hazard reduction burns over thousands, if not tens of thousands of hectares.
03:07 And what this work shows is that some of that country will be made more flammable, not less.
03:13 And our perspectives on this is that if we are going to do prescribed burning, you need
03:17 to do it very frequently and you need to do it very close to where it matters.
03:21 And where it matters is where we're trying to protect people and property.
03:25 So we need to dispense with this idea of burning large areas of remote country, the middle
03:31 of Kosciuszko National Park or the middle of other remote areas, and refocus where we're
03:37 doing that work in places that are going to matter in terms of protecting people and property.
03:42 Yeah, the RFS has pushed back against these findings.
03:45 The Community Risk Director says that reducing fuel loads always reduces risk.
03:52 Do you think there's something that they are not understanding here or refusing to take on?
03:57 I think they're not understanding the basic principles of how forests grow and mature
04:02 and become less flammable as they get older.
04:05 And I think really the evidence is starting to mount here now to indicate that we need
04:11 to have a rethink of how we're doing prescribed burning and focus it where it really matters.
04:18 The budgets to do prescribed burning are not unlimited and the time window to do prescribed
04:26 burning is now narrowing.
04:27 So we need to focus it where we get the best return on investment for protecting the most
04:33 people and the most property.
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