Why Fire Breeds More Fire
The towering forests of the Australian Alps are trapped in a dangerous feedback loop, and the secret lies in their flammability dynamics.
When we think of a forest recovering from a fire, we often imagine a landscape made temporarily safer, its destructive energy spent. But what if the very act of burning made these forests more likely to burn again? In the Australian Alps, this isn't a hypothetical question. For decades, scientists have been piecing together a disturbing puzzle, discovering that these iconic landscapes are caught in a powerful positive feedback cycle where fire actually increases future fire risk. This revelation is transforming our understanding of fire management and sounding an alarm for the future of some of Australia's most vulnerable ecosystems.
The concept is known as flammability dynamics—how a forest's propensity to burn changes over time, particularly after a fire. Conventional wisdom might suggest that after a fire burns through an area, the lack of fuel would make it less likely to burn again for some time. However, recent research examining over 58 years of fire history in the 1.4 million hectare forested area of the Australian Alps has turned this assumption on its head 4 .
Wildfire burns through mature forest
Dense, low-growing vegetation replaces tall canopies
Rapid growth creates fine, flashy fuels
Higher likelihood of more intense fires
The findings reveal a landscape where fire creates conditions ripe for more fire. This is particularly true for the tall, wet forests dominated by Ash-type eucalypts. Contrary to popular perception, these forests don't become safer after a fire—they become dramatically more flammable 4 .
The mechanism behind this feedback cycle involves complex changes to the forest structure and fuel composition after a fire:
Mature forests with tall canopies are replaced by dense, low-growing understory vegetation that dries out more quickly and is more prone to ignition.
While it seems counterintuitive, the period after a fire can see rapid accumulation of fine, flashy fuels from recovering vegetation that are perfectly structured to carry fire.
The structure of regenerating forests makes them more susceptible to devastating crown fires—fires that move through the canopy rather than staying at ground level.
This feedback loop has profound implications. As climate change leads to hotter, drier conditions, and as fires become more frequent, the Alps landscape could become permanently more flammable, creating an accelerating cycle that pushes some ecosystems to the brink of collapse 4 .
To understand how we know about these flammability dynamics, let's examine the pivotal 2018 study by Philip Zylstra that provided some of the most compelling evidence for this fire feedback cycle 4 .
Zylstra's approach was both extensive and meticulous:
This multi-faceted approach allowed for comparisons across different forest types and fire regimes, revealing patterns that would be invisible in shorter-term or smaller-scale studies.
The results painted a striking picture of a landscape transformed by its own fire history:
| Forest Formation | Increased Likelihood to Burn After Fire | Strength of Feedback |
|---|---|---|
| Tall, wet forests (Ash-type eucalypts) | More than 8 times as likely | Strongest response |
| Open forest | 1.5 times as likely | Weakest feedbacks |
| Low, dry open woodland | Insufficient data to detect trend | Inconclusive |
Perhaps even more significantly, the research found that all forests were most likely to experience crown fire during their regeneration period 4 . This finding is crucial because crown fires are typically more intense, faster-moving, and more difficult to control than ground fires.
| Forest Condition | Crown Fire Likelihood | Ecological Impact |
|---|---|---|
| Mature stands | Lower | Sustainable ecosystem |
| Regenerating post-fire stands | Highest | Potential ecosystem collapse |
| Tall, wet forest regeneration | Particularly high | Potential shift to more flammable open forest or heathland |
[Interactive chart showing flammability increase over time after fire]
The flammability dynamics in the Australian Alps don't exist in isolation. They intersect with broader climate patterns and historical management practices that together create the fire challenges we face today.
Recent research continues to validate and expand upon our understanding of these dynamics. A 2025 study highlights how drought, topography, and forest management collectively shape wildfire occurrence and severity in montane Australian landscapes . Drought stress appears to be a critical factor that can amplify the inherent flammability of post-fire landscapes.
The science of fire management in these ecosystems has a complex history. A comprehensive review published in Forest Ecology and Management examined more than 500 research documents related to fuel management in the high country of southeastern Australia 1 .
The review revealed significant gaps in our knowledge, particularly regarding fuel loads, and noted that the quality of research has improved markedly each decade since WWII.
Importantly, it highlighted that future management will require a greatly increased research effort 1 , suggesting that Zylstra's work is part of an evolving scientific understanding.
What does it take to study these complex fire dynamics? Modern fire ecology relies on a sophisticated toolkit that combines traditional field methods with cutting-edge technology.
| Tool or Method | Function | Application in Australian Alps Research |
|---|---|---|
| Historical fire mapping | Tracks fire scars over time | Created 58-year fire history database 4 |
| Satellite remote sensing | Measures vegetation recovery and fire effects | Analyzed crown fire impacts from 2003 fires 4 |
| Flammability ratio | Quantifies likelihood of ignition | Compared burn probability across forest types 4 |
| Fuel load assessment | Measures combustible material | Evaluated effectiveness of fuel reduction burning 1 |
| Climate data analysis | Correlates weather patterns with fire | Studied drought impact on fire occurrence |
Early fire research begins with basic observations and limited data collection methods.
Systematic fire mapping begins, establishing baseline data for future studies.
Devastating fires provide extensive data on crown fires and their impacts.
Comprehensive analysis of 58 years of data reveals flammability feedback cycles.
Studies incorporate climate change impacts and refine flammability models.
The discovery of strong positive flammability feedbacks in the Australian Alps has reverberations beyond this specific region. It challenges fundamental assumptions in fire management worldwide and forces a reconsideration of how we approach forest conservation in an era of climate change.
For the tall, wet forests of the Alps, the implications are particularly dire. The research suggests that frequent fire promotes ecosystem collapse into either the more flammable open forest formation or to heathland 4 . This represents a potentially permanent loss of complex forest ecosystems that have defined the region for millennia.
As climate change increases the frequency and intensity of fires globally, understanding these flammability dynamics becomes increasingly urgent. The Australian Alps serve as both a warning and a laboratory—a place where we can see the future of fire-prone landscapes and develop the knowledge needed to manage them more effectively.
The challenge now is to translate this understanding into management strategies that can break the cycle of increasing flammability before these unique ecosystems cross the threshold of irreversible change.
The forests of the Australian Alps stand at a crossroads, their future depending on our ability to understand and adapt to the complex dynamics of fire that we've only begun to comprehend.