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How long will it take for burnt NPs to go back to 'normal'?

Sat 25 Sep, 2021 8:13 pm

Hi all,

Fairly basic question that I'm having trouble answering.

Wollemi\Yengo\Upper Blue Mtns NP etc all burnt in 2019\2020 and are regenerating nicely.

I'm just wondering what the timeline for that is, how long will it take until the NPs resemble what they were pre-fire. By which I mean closed canopies etc - no more pioneer species undergrowth etc.

5 years, 10 years, 20 years?

Thanks all.

Re: How long will it take for burnt NPs to go back to 'norma

Sat 25 Sep, 2021 8:45 pm

Here in Tassie many of them will never return to "normal"

Re: How long will it take for burnt NPs to go back to 'norma

Sat 25 Sep, 2021 9:37 pm

I'm no pro but would think 5 years with good rainfall. Which many places haven't had consistently/per history.
So could be longer.
Sometimes a loss of canopy is a bonus for understory plants to get more light and have a bumper season.
Also some species shed bark, others retain bark so the black trunks etc could remain a long time.

Edit. Something else I've noticed in some burnt areas is medium and large trees survived, smaller trees and saplings were burnt to death. This could mean a generational gap in flora of a decade, dunno if that's bad for trees, it is less good for shrubs and shorter lived species.

Re: How long will it take for burnt NPs to go back to 'norma

Sun 26 Sep, 2021 8:16 am

It might be difficult to answer the question accurately. To this we'd really need to know what the "normal" was and I don't think that there was enough real research done to determine that and with the climate changing so rapidly do you mean the old normal or the new and as yet undetermined new normal.
My guess is somewhere between Neos 3 to 5 years and maybe one or two hundred years

Re: How long will it take for burnt NPs to go back to 'norma

Sun 26 Sep, 2021 7:11 pm

There's no simple answer to this question. Different communities of plants will recover at different rates, while some will change substantially from their previous composition. Left to their own devices most Eucalypt forests in SE Australia would generally be expected to reach their mature state after 20 to 50 years, however most of these forests experience fire at much shorter intervals than this now due to prescribed burning. Rainforest environments burnt in the recent fires are likely never to recover, but to be replaced by pyrophillic species such as Eucalypts. One thing you will see are substantial populations of Acacia species regenerating quickly following the fires - a trip to Yerranderie at present would be a good example. They are a classic pioneer genus in these forests, that respond quickly to fire in huge numbers. They are soil nitrogen fixing plants that generally have relatively short (5-20 year) life spans, before giving way to Eucalypts. As I mentioned before though, the increased fire frequency in these forests is interfering with this cycle. And as Moondog observed, climate change is also going to affect the recovery/evolution of these forests.

Re: How long will it take for burnt NPs to go back to 'norma

Sun 26 Sep, 2021 9:00 pm

Hughmac wrote:There's no simple answer to this question. Different communities of plants will recover at different rates, while some will change substantially from their previous composition. Left to their own devices most Eucalypt forests in SE Australia would generally be expected to reach their mature state after 20 to 50 years, however most of these forests experience fire at much shorter intervals than this now due to prescribed burning. Rainforest environments burnt in the recent fires are likely never to recover, but to be replaced by pyrophillic species such as Eucalypts. One thing you will see are substantial populations of Acacia species regenerating quickly following the fires - a trip to Yerranderie at present would be a good example. They are a classic pioneer genus in these forests, that respond quickly to fire in huge numbers. They are soil nitrogen fixing plants that generally have relatively short (5-20 year) life spans, before giving way to Eucalypts. As I mentioned before though, the increased fire frequency in these forests is interfering with this cycle. And as Moondog observed, climate change is also going to affect the recovery/evolution of these forests.


I'm starting to appreciate the difficulty in answering this question.

But take the Grose valley for example, most of the crowns are gone but virtually all the trees are alive and doing that "sprouting new branches from all sides" thing that they do. While I do appreciate that some species' populations will be permanently shifted by these fires, these big eucalypts aren't going anywhere so surely there must be a timeframe. What I consider "normal" is essentially just a restoration of the tree-crowns of these big trees - as without them walking in summer will be painfully exposed.

February 2020 was not a pleasant time to be out!:

20200201_120638_HDR.jpg

Re: How long will it take for burnt NPs to go back to 'norma

Mon 27 Sep, 2021 9:07 am

The answers to your question certainly make interesting reading..,there is a wide variety of answers as you would expect when you ask a group of randoms a question where most participants obviously have a pretty limited understanding of the factors involved.

To be fair those few among us with a fair handle on fire ecology can only give an educated guess that could be wide of the mark in attempting to nswer your question without knowing the critical factors which will come into play in the future.

Those listening will realise our climate has changed, the changes appear to be accelerating, and many affects have long lag times. Many of the changes that have happened and will become apparent will be totally irreversable for many hundreds of years and the critical question is "can the annihilation of life as we know it be averted" through an unlikely concentrated and united effort by mankind.

Its certainly possible the "recovery" you describe will happen in places, at least on a temporary basis, at some undetermined time, but there are too many unknowns to say when.

Re: How long will it take for burnt NPs to go back to 'norma

Mon 27 Sep, 2021 9:19 am

Admittedly the recent bushfires were extraordinary, but bushfires and regeneration are in general, a normal part of our landscape. The way it is now, is just a different type of normal.

What isn’t normal is the dumb, one size fits all approach to prescribed burning. It’s been shown in some environments, regular fires create greater fuel loads, not less. Ecologies where plants take 15-50 years to fully regenerate, will be wiped out due to political expediency taking precedence over scientific knowledge.

Re: How long will it take for burnt NPs to go back to 'norma

Mon 27 Sep, 2021 9:59 am

crollsurf wrote:
What isn’t normal is the dumb, one size fits all approach to prescribed burning. It’s been shown in some environments, regular fires create greater fuel loads, not less. Ecologies where plants take 15-50 years to fully regenerate, will be wiped out due to political expediency taking precedence over scientific knowledge.


This shows a total lack of understanding of what can be achieved by fuel reduction burning. There is no one size fits all prescription for fuel reduction burning..the prescription needs to be tailored to site, using well-defined scientific principles. If a fuel reduction burn does not achieve the desired result then the prescription for the burn needs to be modified so the desired result is achieved.

While fuel reduction burning may not stop a catostrophic wildfire at full steam, the science is ovewhelming that fuel reduction reduces fire intensity and can mean a fire is cotained before it turns into a catastrophic fire.

Its one of the very few things that can make a difference. But you probably need to fight a fire to understand that, which is why so many dont understand hiw and why fuel reduction works

Re: How long will it take for burnt NPs to go back to 'norma

Mon 27 Sep, 2021 11:29 am

ghosta, I think you are reading things I didn't say. I'm not saying we shouldn't burn. I'm only going off what the experts say. Maybe the situation in Tassie is different to NSW. In NSW prescribed burning has become politized, they just want to burn, burn burn regardless.

Unfortunately I can't find a specific study I read a few years back (Central Coast NSW) but the study concluded there was an initial reduction in fuel loads for about 3 years, but after that, fuel loads were even greater than before, for about 10 years (don't quote me). Until finally the fuel loads returned back to their original levels. So a few years of reduced loads, followed by roughly 10 years of increased fuel load! Not my opinion, the findings of a long term study done a few decades ago.

I did find this however https://www.aph.gov.au/About_Parliament/Parliamentary_Departments/Parliamentary_Library/Publications_Archive/CIB/cib0203/03Cib08
"While it is intended that fuel reduction burns will be successful in reducing fuel levels with the minimum of damage to the forest, this is not always the case. Post burn assessments of the effectiveness of prescribed burns in the Blue Mountains in the period 1990 97 found that 30 per cent of the burns had a negative result, 40 per cent were sub-optimal, and 30 per cent could be rated as effective burns.(31) The negative results occurred when there was more "creation of fuel" than reduction of fuel...


I admit I have plucked a quote that suits my argument but once again, not my opinion but that of a 7 year study.
Last edited by crollsurf on Mon 27 Sep, 2021 5:57 pm, edited 1 time in total.

Re: How long will it take for burnt NPs to go back to 'norma

Mon 27 Sep, 2021 12:45 pm

The rampaging hoards of Post-covid boom and social media boom hikers are already contributing to a changing and damaged environment in bushfire affected areas.

Its a generalisation yes, but the widespread mentality these people bring with disrespect for rules, conservation, protection and maintaining enjoyment for others in these areas is incredibly frustrating.

Re: How long will it take for burnt NPs to go back to 'norma

Tue 28 Sep, 2021 1:15 pm

Down here in Victoria, Kinglake burned in 2009 and I'd say its just about to start returning to so called "normal" status. Kinglake gets a reasonable amount of rain over winter so that certainly helps...so I'd say optimistically that it takes min 10 years.

Re: How long will it take for burnt NPs to go back to 'norma

Thu 30 Sep, 2021 1:59 pm

Thanks all. Some very interesting replies.

I'm going to tell myself it'll take about a decade for the tree canopy to close up again in the Grose\Wollemi etc. I know for some this may seem overly optimistic, but hey someone has to be ;)

-Richard

Re: How long will it take for burnt NPs to go back to 'norma

Sat 02 Oct, 2021 1:04 pm

As keen as most bushwalkers are about nature, I doubt you'll find the requisite expertise here.

One of the few reasons I use Twitter is the fact that so many good ecologists are on there. People who study these landscapes intimately are really best placed to answer your question.

One ecologist who has worked in the Blue Mountains for decades, and who I know personally through bushwalking and conservation circles, is Roger Lembit (https://twitter.com/rsl1957/). He recently tweeted the below from one of his sites on the Newnes Plateau. His view is that he won't live long enough to see that ecological community recover. One of the things people don't realise is that not all gum trees respond well to fire. In the higher altitudes (or southern latitudes) many do not. In the Blue Mountains, the mountain ash is a good example.

roger.jpg
roger.jpg (136.78 KiB) Viewed 2307 times


The word "unprecedented" got a lot of use when people were talking about the size and scale of the 2019/20 bushfires. What often gets overlooked was how unprecedented the situation was leading up to the fires. The extreme heat and drought -- driven by a changing climate -- left the bush so much drier than previously. That's why the fires burnt so fast and far.

What the fires covered up was that fact that our hotter, drier summers are changing the landscape without fires. In my part of the lower Blue Mountains, which didn't burn, we saw this acutely. Many trees lost most of their canopies that summer. When they regrew, it was epicormic growth (sprouting from the trunk) as if they'd been burnt. It was simply the hot, dry summer that caused that stress. Many trees didn't come back at all, and I walk past dozens of dead trees killed by that summer (without fire). People who walk regularly in the area noticed a mass die-off of the Banksia serrata (Old Man Banksias). These are really tough, long-lived plants that grow on rocky ridgetops. Again, they didn't burn, they were just killed by the changing climate.

If extreme weather continues to become more frequent, with longer hot, dry spells in summer, we will see a radical loss of vegetation. Many ridgetops will transition from open forest to low scrub as the trees die off. That process has certainly started in my local area.

Re: How long will it take for burnt NPs to go back to 'norma

Sat 02 Oct, 2021 2:47 pm

Hi FC. I live at Moss Vale, and the same impacts of the drought are evident in the Highlands. Mount Gibraltar (The Gib as it is known locally) is home to an endangered ecological community, and now looks like it is recovering from a bushfire, however there was no fire there. Viewed from below it is covered in the bare branches of dead trees. The impacts are less apparent at lower elevations, but obvious if you are paying enough attention. And as I noted above, many of the Gondwandan rainforests destroyed by the fires will never recover. It is incredibly depressing that we have been warned about the impacts of climate change for at least four decades now, but are still yet to take meaningful action to address it. The environments we know and love will in many cases soon be unrecognisable to us, purely the result of human greed and stupidity.

Re: How long will it take for burnt NPs to go back to 'norma

Sat 02 Oct, 2021 3:47 pm

FatCanyoner wrote:If extreme weather continues to become more frequent, with longer hot, dry spells in summer, we will see a radical loss of vegetation. Many ridgetops will transition from open forest to low scrub as the trees die off. That process has certainly started in my local area.


I've noticed changes in my local bit of bush also. As a kid there was very little undergrowth and lots of large redgums. Now most of the large redgums are dead and the scribbly gums are looking worse for ware, the undergrowth is bubbling up and everything is carpeted thickly with dry sticks. It's a lot more open than it used to be. Lots of natural sandstone caves have also been graffitied in recent years - council refuses to clean.

If the Wollemi gets turned into a wasteland I'm becoming a terrorist, that's all I've got to say :( :evil:

I threw a k at the Colong Foundation in light of this thread. What else can one do...

Hughmac wrote:Hi FC. I live at Moss Vale, and the same impacts of the drought are evident in the Highlands. Mount Gibraltar (The Gib as it is known locally) is home to an endangered ecological community, and now looks like it is recovering from a bushfire, however there was no fire there. Viewed from below it is covered in the bare branches of dead trees. The impacts are less apparent at lower elevations, but obvious if you are paying enough attention. And as I noted above, many of the Gondwandan rainforests destroyed by the fires will never recover. It is incredibly depressing that we have been warned about the impacts of climate change for at least four decades now, but are still yet to take meaningful action to address it. The environments we know and love will in many cases soon be unrecognisable to us, purely the result of human greed and stupidity.


It's hard to shake the feeling that every year some more magic leaves the world forever. As a young person, I find it difficult to be optimistic about the future at times...

Re: How long will it take for burnt NPs to go back to 'norma

Sat 02 Oct, 2021 9:06 pm

It's hard to shake the feeling that every year some more magic leaves the world forever. As a young person, I find it difficult to be optimistic about the future at times...
I am actually thankful that I am closer to my grave than my birth. As a kid my life revolved around looking for lizards, frogs and tortoises in the bush (we drew the line at snakes). As a young adult I thought that advances in science would lead to a more enlightened population that appreciated the wonders and importance of the natural world they lived in. Boy was I wrong. Increased knowledge has been accompanied by increased greed and ignorance. To say that biodiversity on the planet has been decimated during my lifetime would be a massive understatement. I share both your despair and your anger, but you want to be careful about what you say in these public forums, or you'll have Dutton's Blackshirts knocking on your door.
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