This response relates to the ongoing debate on ARR.News: Open for Debate – Bushfires, Logging, Burns & Forest Management

On CSIRO Snapshot December 2021, there is an article titled Black Summer fires linked to climate change. It notes “our new research shows climate change has driven a significant increase in Australia’s forest fire activity over the last three decades.”

See also: New research links Australia’s forest fires to climate change: CSIRO

There is a question in the above article “Could fuel loads or prescribed burning be to blame? The authors comment notes “No. We looked for trends in these factors, and found nothing to explain the rise in burnt areas”.

In relation to this comment in regards to prescribed burning and fuel loads, I provide quick points below:

1. The issue is very important, as fire fighter and community/ town/ infrastructure safety is a major issue in all this. Forests are often very dangerous places, it is essential that fuel loads and fuel strata/ 3 D fuels are managed, setting up safe and health landscapes. Too many people and fauna have died in past bushfires.
2. In the paper that the authors released they use an average of 1 % prescribed burning across Australia. They note “only 1% of forests are subject to fuel reduction burns every year, it is very likely that fuel management had no effect on the observed multi-decadal increasing trend in the burned area of forest fires” The authors note elsewhere in an article that “this is a really small amount”, and I totally agree it is, but at unsatisfactory levels. This is the issue, the prescribed burning in eastern states has been way too low over a very long period, and fuel loads and 3D fuels continue to increase as they have over the last 30 years, safe levels of fuels haven’t been achieved and are getting worse.
3. The incidence of large wildfires in Western Australian forests over the last 67 years data unequivocally show that when the area of prescribed burning trends down, the area of uncontrolled bushfires (wildfires) trends up. The ideal area of forest burnt annually appears to be about 8 %.
4. The WA prescribed burning data has been combined with eastern data, as noted elsewhere this is like comparing apples with oranges. A key weakness is the bundling together of quite different forest types and management practices between west and east. In WA, the prescribed burned area is nearly half the national total, but it has considerably less forest area than the big eastern states. By bundling WA into the analysis, the authors arrive at conclusions that do not appear to be valid: For example: They say: “However, given the lack of trend and the fact that on average, only 1% of forests are subject to fuel reduction burns every year, it is very likely that fuel management had no effect on the observed multi-decadal increasing trend in the burned area of forest fires”. This includes much undetectable controlled burning in other states with wetter forests, but this does not apply nearly so strongly in WA (with some 1-2 million ha/year of controlled burning in mainly in more open jarrah forest).
5. On data I have, areas of annual prescribed burning in NSW have reduced since 2000. The 1998 NSW Auditor General performance audit report refers to 600,000 hectares per year in NSW around the year 2000 in NSW. The prescribed burning of the 7 million hectares of NPWS land in 2020/ 21 was 53,145 ha, which is 0.76 % of NPWS lands.
6. It is important to note that prescribed burning is not expected to stop fires, it reduces intensity and damage.
7. I suggest that there is an inbuilt bias in the CSIRO data, Modis/ Landgate would increase fire/bushfire areas in more recent years, as well as potentially pick up mild burning, they have tried to explain this. As well, in earlier years, much of the private/ freehold/ lease prescribed burning would not have been recorded.
8. Reduced grazing in previous State Forests and transfer of lands to parks is another issue increasing fuel loads and increasing bushfire risks. Another potential influence in the data is the increasing population over time, increasing bushfire risks over time. I am not sure if arson has increased.
9. Safe and healthy landscapes and chronic eucalypt decline has been missed as an issue. Mild burning is needed to keep forests healthy, something they aren’t in many cases.
10. There are many many authors and practitioners who have highlighted the importance and success of mild burning across landscapes in managing and reducing fuels.
11. Fuel loads in the CSIRO paper are simulated. Provision of actual (not simulated) fuel loads in forests across landscapes in NSW and other eastern states is warranted, to tease out fact from fiction.
12. It is important to highlight the fact that human fires have had a pivotal role in Australia’s ecological history. A useful reference Vic Jurskis, Roger Underwood, Neil Burrows. How Australian Aborigines Shaped and Maintained Fire Regimes and the Biota. Ecology and Evolutionary Biology. As noted recently, the 1824 and 1851 bushfires in Victoria resulted very quickly in terms of timeframes from increased fuel loads and scrub thickening after Aboriginal dispossession and disease which decimated the Aboriginal people and their burning practices. The estimated areas for the 1851’s bushfires was 5 million hectares. Key information such as this, human fires and Aboriginal cultural burning evidence, provides land managers with information to undertake adaptive land and fire management practices.

Related: New research links Australia’s forest fires to climate change: CSIRO and responses at Open for Debate – Bushfires, Logging, Burns & Forest Management

About John O’Donnell

John is a retired district forester and environmental manager for hydro-electric construction and road construction projects.   His main interests are mild maintenance burning of forests, trying to change the culture of massive fuel loads in our forests setting up large bushfires, establishing healthy and safe landscapes, fire fighter safety, as well as town and city bushfire safety.