Some reports and popular books, such as Bill Gammage's Biggest Estate on Earth, have argued that extensive areas of Australia's forests were kept open through frequent burning by First Nations people. Advocates for widespread thinning and burning of these forests have relied on this belief. They argue fire is needed to return these forests to their "pre-invasion" state.

Some reports and popular books, such as Bill Gammage’s Biggest Estate on Earth, have argued that extensive areas of Australia’s forests were kept open through frequent burning by First Nations people.

A key question then is: what does the evidence say about what tall, wet forests actually looked like 250 years ago? The answer matters because it influences how these forests are managed.

Our key conclusion is that these forests were not open or park-like-as was the case in some other vegetation types in Australia.

The compelling evidence we compiled all indicates mountain ash forests were dense, wet environments, not open and park-like, at the time of British invasion.

  • Treevan 🇦🇺@aussie.zoneOPEnglish
    5·
    7 months ago

    Lindenmayer et al. have published on this recently.

    https://onlinelibrary.wiley.com/doi/10.1111/aec.13096 - What are the associations between thinning and fire severity?

    https://conbio.onlinelibrary.wiley.com/doi/10.1111/conl.12766 - Does forest thinning reduce fire severity in Australian eucalypt forests?

    And some choice quotes from other works:

    Across all forests in the Greater Blue Mountains World Heritage Area in the Australian State of New South Wales, the probability of canopy scorch or crown burn remained high until 20 years post fire, but then declined to near zero by 30 years (Barker & Price, 2018).

    The latter study also showed that the likelihood of canopy-damaging fires was related to the severity of the previous fire, so that one fire in disturbed forests set in motion an accelerating likelihood of future severe fires. Crown burn was most likely in dry sclerophyll forests of south-eastern Australia if they had been burned in the previous 5–15 years (Storey, Price & Tasker, 2016).

    Whereas the forests and woodlands discussed above exhibited an initial brief reduction in flammability that preceded a more flammable regrowth period caused by the disturbance, this pattern was not detectable on an annual scale in an analysis of fire trends in Kakadu National Park in the Australian tropics. Flammability decreased linearly from the first year, reaching a near-zero likelihood of wildfire in all communities by 15 years (Gill et al., 2000).

    Analysis of long-term fire records for Southwest Australian eucalypt forests has confirmed these expectations, demonstrating that long-unburnt forests are 7.4 times less likely to burn than forests still recovering from fire (Zylstra et al., 2022).

    A mechanistic analysis of red tingle (Eucalyptus jacksonii) forest in south-western Australia, for example, demonstrated that mature forest facilitated more successful application of fire-suppression techniques than disturbed forests under the same weather conditions (Zylstra et al., 2023).

    At a global scale, the predominance of young forest may represent a major challenge in fire management. For instance, McDowell et al. (2020) reported that the percentage of young forest stands (< 140 years old) has increased from 11.3% in 1900 to 33.6% in 2015 of the total forest area at the global scale.