Australia’s eucalyptus forests are among the most distinctive and ecologically significant landscapes on Earth. Covering vast stretches of the continent—from the temperate highlands of Victoria to the tropical woodlands of Queensland—these forests define much of what makes Australia’s natural environment so unique. They are not simply a backdrop to Australian life; they are an active, dynamic system that shapes the land, the climate, and the cultures that have evolved alongside them.
For millions of years, eucalyptus trees, collectively known as gum trees, have dominated the Australian landscape. Today, the genus Eucalyptus comprises over 700 species, the overwhelming majority of which are native to Australia. This extraordinary diversity is the result of millions of years of evolution in isolation—a process driven by Australia’s nutrient-poor soils, unpredictable rainfall, and a fire regime unlike anything found elsewhere on the planet.
This article explores eucalyptus forests in depth: their ecological structure, biological diversity, cultural significance, and the growing pressures threatening their long-term survival. Understanding these forests is essential—not only for those who study them, but for anyone invested in the future of the world’s natural systems.
The Ecological Structure of Eucalyptus Forests
Eucalyptus forests vary considerably in structure depending on climate, soil type, and altitude. At the broadest level, they can be divided into tall open forests, dry sclerophyll forests, and mallee shrublands—each representing a distinct ecological community.
Tall open forests, found in high-rainfall regions such as the Central Highlands of Victoria and the forests of southern New South Wales, are among the most structurally complex. Mountain ash (Eucalyptus regnans)—the world’s tallest flowering plant—anchors these ecosystems, with mature trees reaching heights of over 90 meters. Beneath the canopy lies a dense understory of tree ferns, wattles, and ground-layer plants, creating a multi-layered habitat of remarkable richness.
Dry sclerophyll forests, by contrast, occupy lower-rainfall zones across much of southeastern and southwestern Australia. These forests are more open in structure, with a grassy or shrubby understory dominated by species adapted to periodic drought. Despite their more austere appearance, dry sclerophyll forests support a high degree of biodiversity, particularly among reptiles, ground-nesting birds, and invertebrates.
Mallee eucalypts—multi-stemmed shrubs that regenerate from a woody underground structure called a lignotuber—form extensive low woodlands across the semiarid interior. These ecosystems are highly adapted to drought and fire, and their resilience under extreme conditions makes them a compelling subject of ecological study.
Biodiversity Within Eucalyptus Ecosystems
The biodiversity supported by Australia’s eucalyptus forests is staggering. These forests provide food, shelter, and nesting sites for a wide array of native fauna, many of which have evolved in close association with specific eucalyptus species.
Koalas (Phascolarctos cinereus) are perhaps the most iconic example of this co-evolution. Koalas feed almost exclusively on eucalyptus leaves—a diet so toxic and nutritionally poor that most mammals cannot survive on it. Through specialized digestive adaptations, koalas detoxify the chemical compounds in the leaves and derive sufficient energy from a diet that is essentially unavailable to other large mammals. Their habitat preferences are highly specific, with different populations favoring different eucalyptus species depending on the region.
Arboreal marsupials such as greater gliders (Petauroides volans) and yellow-bellied gliders (Petaurus australis) rely on old-growth eucalyptus trees for nesting hollows—cavities that take over 150 years to develop in species like mountain ash. This dependency on old trees means that logging of old-growth forest has severe consequences for hollow-dependent species, many of which are now listed as threatened.
Eucalyptus flowers are also a critical food source for nectar-feeding species. Honeyeaters, lorikeets, and swift parrots migrate across vast distances to follow the flowering cycles of various eucalyptus species. The swift parrot (Lathamus discolor), critically endangered, depends almost entirely on the blue gum (Eucalyptus globulus) and manna gum (Eucalyptus viminalis) forests of Tasmania for breeding.
Invertebrate diversity in eucalyptus forests is equally remarkable. A single old-growth eucalyptus tree can host hundreds of invertebrate species, including beetles, moths, and spiders—many of them specialists that cannot survive in younger or disturbed forest.
The Role of Fire in Shaping Eucalyptus Forests
Fire is inseparable from the story of eucalyptus forests. Many eucalyptus species are not merely fire-tolerant—they are fire-dependent, having evolved traits that encourage, survive, and respond to burning. The bark of species like stringybarks is highly flammable and sheds in long strips, carrying fire through the canopy. Oils in eucalyptus leaves are volatile, contributing to the explosive fire behavior for which Australian bushfires are known.
Yet within days of a fire, many eucalyptus trees begin to regenerate. Epicormic buds—dormant growth points located beneath the bark—activate rapidly after a fire, producing new foliage from the charred trunk and branches. Lignotubers provide a carbohydrate reserve that fuels regrowth in mallee species. Serotinous seed capsules in some species remain closed until heat from a fire triggers their release, ensuring that seeds are dispersed into the ash bed immediately after burning.
This suite of adaptations speaks to a long evolutionary history with fire. Aboriginal Australians recognized and worked with this relationship for tens of thousands of years, using controlled burning—known as cultural burning or fire-stick farming—to manage the landscape, encourage the growth of food plants, and maintain habitat diversity. These practices profoundly shaped the structure and composition of eucalyptus forests long before European settlement.
Contemporary fire management is considerably more complex. Climate change has extended fire seasons, increased temperatures, and reduced the moisture content of vegetation. The catastrophic bushfires of 2019–2020—known as the Black Summer—burned approximately 18.6 million hectares across southeastern Australia, including vast areas of forest that had not burned for decades. The ecological consequences were severe: an estimated three billion vertebrate animals were killed or displaced, and several eucalyptus-dependent species suffered population losses that pushed them closer to extinction.
Cultural and Indigenous Significance
Eucalyptus forests are not solely ecological entities. For Aboriginal and Torres Strait Islander peoples, these forests are deeply embedded in culture, spirituality, and traditional knowledge systems that extend back over 65,000 years.
Many eucalyptus species hold significant medicinal, practical, and ceremonial value. The steam from eucalyptus leaves has been used medicinally to treat respiratory ailments. Bark and timber were used to build shelters, canoes, and tools. The flowers and sap provided food sources. And across many language groups, specific trees and forest areas are connected to Dreaming stories—complex cosmological narratives that encode knowledge of country, seasonal change, and ecological relationships.
The revival of cultural burning practices in recent decades has been driven in large part by Aboriginal communities who argue, with considerable scientific support, that Indigenous fire management techniques are more ecologically effective than the suppression-based approaches that followed European colonization. Organizations such as the First Nations-led cultural burning network across Victoria and New South Wales have been instrumental in bringing these practices back into land management frameworks.
Conservation Status and Threats to Eucalyptus Forests
Despite their ecological importance, eucalyptus forests face a range of serious and mounting threats. Land clearing for agriculture and urban development has reduced the extent of eucalyptus forest significantly since European settlement, with some estimates suggesting that more than 50% of Australia’s original forest cover has been cleared or substantially modified.
Logging of old-growth forest remains controversial. The Victorian Central Highlands, home to mountain ash forests and critical habitat for the Leadbeater’s possum—Victoria’s faunal emblem—has been the subject of protracted legal and political conflict. In 2020, the Victorian government announced an end to native forest logging by 2030, a decision welcomed by conservationists but contested by the timber industry.
Introduced species present another significant challenge. Deer, feral pigs, and rabbits browse regenerating eucalyptus seedlings, while invasive plants outcompete native understory species. Phytophthora cinnamomi—a water mold responsible for jarrah dieback—has devastated eucalyptus forests in southwestern Australia, particularly in the jarrah (Eucalyptus marginata) forests of the Darling Range.
Climate change overlays all of these pressures. Modeling by CSIRO and the Australian Bureau of Meteorology projects significant changes to rainfall patterns, temperature extremes, and fire weather across eucalyptus forest regions. Some species are expected to shift their ranges southward and to higher elevations in response to warming temperatures, but the pace of change may exceed the capacity of forest ecosystems to adapt.
The Global Importance of Australian Eucalyptus Forests
Beyond their national significance, Australia’s eucalyptus forests contribute to global biodiversity and climate regulation in ways that are increasingly recognized by the international scientific community. These forests store substantial quantities of carbon—mountain ash forests, for example, are among the densest carbon stores of any forest type on Earth, according to research published in the journal Global Change Biology.
Eucalyptus trees have also been widely planted outside Australia, particularly in South America, Africa, and southern Europe, where they are grown for timber, pulp, and fuel. While plantation eucalypts offer certain economic advantages, they lack the ecological complexity of native Australian eucalyptus forests, and their introduction in some regions has raised concerns about water use, soil impacts, and displacement of native vegetation.
A Future Worth Protecting
Australia’s eucalyptus forests are a living archive of evolutionary history, ecological complexity, and cultural knowledge. They house species found nowhere else on Earth, support Indigenous cultural practices of extraordinary depth, and provide ecosystem services—carbon storage, water regulation, biodiversity habitat—that extend well beyond the forests themselves.
The challenges they face are real and urgent. But so too are the tools available to address them: improved fire management, land tenure reform, targeted conservation investment, and the growing integration of Indigenous knowledge into land management policy. Each of these represents a practical, evidence-based path toward greater forest resilience.
Protecting eucalyptus forests is not an act of sentiment. It is a matter of ecological and cultural necessity—one that demands sustained attention from governments, researchers, communities, and the broader public alike.