Australian forests are losing trees at an accelerating rate, signalling a shift in vegetation as the climate warms and dries. That is according to a new study published in Nature Plants, which draws on more than eight decades of data to reveal a continent‑wide rise in background tree mortality.
Led by Western Sydney University and supported by James Cook University (JCU), the research analysed 83 years of records from more than 2700 long‑term forest plots across Australia. It is the first national‑scale synthesis of “background mortality” — tree deaths not caused by fire, clearing or logging — spanning tropical rainforests, savannas and temperate eucalypt forests.
And the results are sobering.
Tree mortality has increased steadily since the 1940s, and the trend is remarkably consistent across all forest types. Over the same period, tree growth has either stagnated or slowed, indicating that the surge in deaths is not part of a natural renewal cycle, but a sign of a growing imbalance between growth and loss.
JCU Associate Professor Michael Liddell, a co‑author who contributed tropical rainforest data, said the findings underscore the irreplaceable value of long‑term ecological monitoring.
“As climate change reshapes the questions we ask of forest systems, long‑term datasets are becoming increasingly important for answering them with confidence,” he said. “Measuring trees is where we start, but on its own, it isn’t enough. We need to track carbon fluxes and faunal biodiversity to understand how ecosystems are responding to a rapidly warming climate.”
The study shows that the decades‑long rise in mortality closely mirrors Australia’s warming and drying climate, with rising temperatures emerging as the dominant driver. Tree deaths are increasing fastest in hot, dry regions and in dense forests where competition for water and light intensifies stress.
According to Belinda Medlyn, a Distinguished Professor from Western Sydney University’s Hawkesbury Institute for the Environment, the trend points to mounting stress across Australia’s forests.
“Australians rely on their forests for cultural values, recreation, biodiversity, and timber,” she said. “Increasing tree mortality will affect all of these. A particular concern is the decline in carbon storage. Forests worldwide absorb about one‑third of human carbon dioxide emissions. If mortality continues to rise while growth stagnates, that buffering capacity will erode.”
The study also highlights a worrying decline in Australia’s forest‑monitoring capacity. Over the past 25 years, the number of long‑term plots being tracked has fallen sharply, reducing the nation’s ability to detect and respond to ecological change.
Professor Medlyn said the findings make a compelling case for renewed investment in long‑term monitoring: “Our results highlight the critical need for ongoing forest monitoring designed to detect long‑term trends, in order to guide effective forest management for the future.”
For more information: Lu, R., Williams, L.J., Trouvé, R. et al. Pervasive increase in tree mortality across the Australian continent. Nat. Plants (2026). https://doi.org/10.1038/s41477-025-02188-2
