Can we keep Australia’s endangered alpine ash on the map? New modelling shows where to focus our efforts

The alpine ash, scientifically known as *Eucalyptus delegatensis*, is one of the most iconic tree species of the Australian Alps, renowned for its towering height and ecological significance. Found primarily in the cool, moist environments of southeastern Australia, these forests play a crucial role in maintaining regional biodiversity and environmental health. They act as significant carbon sinks, helping to mitigate climate change, while also regulating water flow into vital river systems and providing essential habitats for numerous native flora and fauna. Despite their importance, mainland alpine ash forests have recently been classified as endangered, marking a critical turning point in conservation efforts.

The primary threat to these forests stems from the increasing frequency and intensity of bushfires, exacerbated by climate change. Over the past few decades, hotter and drier conditions have led to more extensive wildfires, such as the catastrophic "Black Summer" fires of 2019–2020. These fires have had a profound impact on alpine ash populations, particularly due to the species' unique biological characteristics. Alpine ash is classified as an "obligate seeder," meaning it relies on seeds released after fire events to regenerate. While this adaptation enables rapid recovery following disturbances, it also makes the species highly vulnerable to repeated burning. If fires occur too frequently, young trees may not reach maturity and begin producing their own seeds, leading to a cycle of regeneration failure and potential local extinction.

To combat this crisis, forest managers have increasingly turned to aerial resowing—a technique involving the use of helicopters or planes to distribute seeds over burned areas. This method aims to restore populations of alpine ash in regions where natural regeneration has failed. Although research suggests that aerial resowing can effectively protect small patches of forest, its long-term effectiveness at a broader landscape level remains uncertain. This uncertainty underscores the need for more comprehensive strategies to ensure the survival of alpine ash.

A recent study conducted by researchers aimed to address these challenges by employing advanced modeling techniques to project the future of alpine ash forests over the next century. The team simulated various climate scenarios and evaluated the interplay between fire regimes, tree maturity, and the efficacy of resowing efforts. Their findings revealed alarming trends: under all projected climate conditions, alpine ash forests are expected to shrink significantly—by up to 65%—within the next hundred years. Even without considering additional warming from future climate change, the existing patterns of fire and temperature are sufficient to drive the species toward extinction.

The implications of these projections are far-reaching. The shrinking of alpine ash forests could lead to substantial losses in biodiversity, disrupt hydrological cycles, and reduce the region's capacity to sequester carbon. Moreover, the transformation of these forests into shrublands or grasslands could alter the entire ecological balance of the area, affecting both plant and animal life. The study highlights the urgent need for targeted conservation interventions, including enhanced resowing programs, improved fire management practices, and possibly the establishment of protected reserves in key areas.

As the situation continues to evolve, stakeholders—including scientists, policymakers, and local communities—are being called upon to collaborate on innovative solutions. The success of these efforts will depend on a combination of scientific understanding, strategic planning, and sustained commitment to preserving one of Australia's most valuable and vulnerable ecosystems. The fate of the alpine ash hangs in the balance, and the coming years will determine whether this remarkable species can continue to thrive on the map of Australia's natural heritage.