We Have Proof Logging Makes Tasmania’s Forests Flammable

Why It Matters

Regrowth‑driven flammability expands the area vulnerable to severe bushfires, complicating land‑management and community protection in Tasmania and similar ecosystems worldwide.

Key Takeaways

• Regrowing forests burned hotter than adjacent mature wet eucalypt stands
• Dense low canopies and dry microclimates drive increased fire intensity
• Damp mature understorey limited fire spread under moderate conditions
• Climate‑driven fire weather may overwhelm this dampening effect

Pulse Analysis

The long‑standing hypothesis proposed by Professor W.D. Jackson in the late 1960s—that young, regrowing wet eucalypt forests become a tinderbox for severe bushfires—has finally been tested in the field. Researchers capitalised on the 2019 Riveaux Road lightning‑ignited fire, which swept through a research site containing both mature, unlogged forest and 40‑year‑old logged regrowth. By comparing pre‑fire measurements of fuel loads, canopy architecture, and microclimate with post‑fire damage assessments, they demonstrated that the regrowth plots experienced markedly higher canopy loss and hotter, drier conditions, confirming Jackson’s predicted high‑risk window.

These results carry immediate implications for fire‑management strategies across Australia’s wet eucalypt landscapes. While the surrounding mature forest’s moist understorey acted as a fire‑break under moderate weather, the study warns that more extreme fire weather—already becoming common due to climate change—could negate this protective effect. The findings also differentiate Tasmania’s eucalypt systems from North American conifer forests, where thinning and prescribed burns have proven effective; in Tasmania, commercial thinning leaves residual bark and debris that may not reduce risk. Consequently, managers must rethink post‑logging treatments, perhaps focusing on removing residual fuels and accelerating canopy development.

Beyond regional concerns, the research underscores a global challenge: vast tracts of regrowth forests worldwide, whether from clear‑cut logging or post‑fire regeneration, may be inadvertently increasing landscape flammability. As climate models predict more frequent and intense fire weather, the 20‑50‑year danger zone identified by Jackson could expand, threatening communities adjacent to forests still in early successional stages. Policymakers, foresters, and fire agencies will need coordinated mitigation plans that balance ecological recovery with proactive fuel‑reduction tactics tailored to eucalypt fire ecology, ensuring that regrowth does not become a catalyst for the next catastrophic bushfire season.