Australia is widely recognised as the most fire-prone continent on Earth. Yet the complex and dynamic interconnection between fire, biodiversity, fire risk, and fire management is not well understood by the majority of the Australian public. Professor David Lindenmayer presents a comprehensive examination of fire as a fundamental ecological process in Australia, emphasising that while fire itself is not new, the regimes under which it occurs are undergoing significant change. He stresses that shifts in fire frequency, sequence, and interaction with other disturbances are central to understanding contemporary fire behaviour and its ecological consequences.
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Summary
Throughout the lecture, Lindenmayer highlights the inherent complexity of fire. He explains that no two fires are the same, with each one being shaped by weather, vegetation, prior disturbance, and spatial patterns across the landscape. Likewise, species exhibit highly individual responses to fire, with varying sensitivities to changes in fire regimes. He underscores that the condition of the environment before a fire plays a critical role in determining its severity and ecological impact.
Drawing on more than 40 years of empirical research, Lindenmayer delves into long-term datasets that reveal how fire interacts with other disturbances such as logging, thinning, and climate change. He identifies climate change as a key driver, contributing to increasingly flammable conditions across Australian forests. However, he also points to land-use practices, including logging and thinning, as significant contributing factors, and that hazard reduction burning may inadvertently exacerbate flammability over time.
A wide examination of large-scale trends in fire regimes, he notes a striking increase in fire frequency. For example, in northern Australia, some regions have experienced up to 35 fires within 23 years, indicating a dramatic shift in tropical savannah fire patterns. At a regional scale, he references Victorian case studies where certain tall wet forests have burned four or more times within 30 years, far exceeding their natural fire intervals of 75 to 150 years.
Disturbance is the driver
A major focus of the lecture is the relationship between forest age, disturbance history, and fire severity. Lindenmayer presents evidence showing that older forests, particularly those over 200 years old, are the least flammable and least likely to experience high-severity fire. In contrast, younger forests are significantly more flammable. He further demonstrates that logging increases fire severity, with logged forests consistently burning more intensely than unlogged forests, even under moderate fire weather conditions. Where young forest age and logging intersect, the effects compound, producing landscapes that are especially vulnerable to severe fire.
He also explores the concept of linked disturbances, where prior disturbance increases the likelihood and severity of subsequent events. In this context, Lindenmayer introduces ideas such as ‘spatial contagion’ and ‘landscape traps’, particularly in relation to how logging influences fire behaviour across broader landscapes (Lindenmayer et al. 2009) (Lindenmayer et al. 2011).
Turning to forest management practices, Lindenmayer critiques the assumption that thinning reduces fire risk. He presents evidence that thinning does not significantly lower fire severity or the likelihood of crown fires and may, in some cases, increase both (Taylor et al. 2020). He notes that forests naturally undergo self-thinning processes, raising questions about the necessity and effectiveness of mechanical intervention given the potential for ecosystem degradation (Lindenmayer et al. 2025).
Looking to the past
Lindenmayer then reflects on historical forest conditions prior to colonisation. He challenges the common perception that Australian forests were uniformly open and frequently burned. In particular, he highlights research suggesting that tall wet forests were historically dense, moist, and not regularly subject to fire. Using tools such as LiDAR alongside ecological evidence, he points to limited signs of frequent burning in these systems. He also references evidence of First Nations tracks in Victoria’s Central Highlands, noting that these landscapes were occupied but not managed through widespread burning or clearing (Lindenmayer et al. 2024).
At the same time, Lindenmayer acknowledges the value of Indigenous knowledge, particularly in the context of cultural burning in appropriate ecosystems such as temperate woodlands. He explains that outcomes of burning differ markedly depending on ecosystem condition: intact woodlands can respond with increased biodiversity, while degraded or heavily grazed systems may instead shift toward weed-dominated regrowth (Bowd et al. 2025).
Hazard reduction or hazard production?
The lecture further examines prescribed burning, with Lindenmayer drawing on Philip Zylstra’s research to highlight its largely short-term effectiveness. He notes that prescribed burning typically reduces fire risk for only five to seven years. Beyond this period, previously burned areas may become more flammable than long-unburnt forests, suggesting that hazard reduction burning can, in some instances, resemble “hazard production” (Zylstra et al. 2022).
He frames this dynamic as a feedback loop, where increased burning leads to a greater need for continued burning (Zylstra & Lindenmayer 2025). This concept of ‘disturbance-stimulated flammability’ illustrates how activities such as logging, repeated burning, and grazing can alter vegetation in ways that increase fire risk (Lindenmayer & Zylstra 2023). He debunks the misconception that practices like alpine grazing reduce fire danger, explaining that such disturbances often replace less flammable grasses with more flammable shrubs.
Importantly, Lindenmayer emphasises that under extreme fire weather conditions, prescribed burning has limited capacity to reduce fire spread, challenging the notion that increasing hazard reduction burning alone can mitigate large-scale fire risk.
A paradigm shift for bushfire management
In discussing fire management, Lindenmayer advocates for a shift away from broad-scale, target-driven prescribed burning toward more strategic and evidence-based approaches. He suggests prioritising fuel management near critical assets and infrastructure and considering alternatives such as mechanical fuel reduction. He argues that large-scale burning in remote areas to meet hectare targets is often ineffective and potentially counterproductive, particularly under extreme conditions.
Finally, Lindenmayer emphasises the need to rethink fire management in Australia by recognising its complexity and addressing the underlying drivers of increased flammability. He calls for reducing unnecessary disturbances, protecting older forests, investing in advanced fire detection and suppression technologies, and strengthening professional firefighting capacity. He also highlights the importance of better-targeted risk management and expanded formal forest protection.
Overall, Lindenmayer’s lecture underscores that effective fire management must move beyond one-dimensional solutions and instead engage with the complex interactions between climate, disturbance, and ecosystem dynamics that shape fire behaviour in Australia.
The article was written by Campbell Goff, the Healthy Ecosystems Program Officer with the Nature Conservation Council of NSW.
Image from Flickr by Mark Jarman at the Office of Environment and Heritage
