Jarrah is not rare.
"A veteran forest scientist with over 60 years of experience studying jarrah has questioned claims that Western Australia’s northern jarrah forests are on the brink of collapse, arguing that the ecosystem remains healthy and resilient despite recent drought events.
The study, “Is the jarrah (Eucalyptus marginata) forest under threat from a changing climate?“, published in Australian Forestry, examines tree health in the Wungong catchment, 50 kilometres southeast of Perth, and draws on decades of field observations, rainfall data, vegetation monitoring, and tree-ring analysis.
“In the summer of 2011 and again in 2024, there was limited but noticeable drought scorch and some deaths of jarrah on sites with shallow soil in the northern jarrah forest of Western Australia,” according to Frank Batini, who authored the study. “As a result, academic and media commentators immediately linked these deaths to human‑induced climate change.”
Batini noted that the Intergovernmental Panel on Climate Change (IPCC), in its 2022 Sixth Assessment Report, listed the northern jarrah forest as at “key risk of transition or collapse from drought (high level of confidence).” This assessment was later adapted and utilised in the Western Australian Government’s Forest Management Plan 2024–2033, which covers the state’s south-west forests.
However, Batini’s research presents a significantly different perspective. The 50‑kilometre reconnaissance road survey in January 2025 found the forest predominantly healthy: “I hypothesise that there is no credible link between human‑induced climate change and the recent deaths observed in the northern jarrah forest,” he said, adding that all ecological changes and tree mortality recorded since 1940 can be explained by soil depth, water‑holding capacity, cyclical rainfall patterns, fluctuations in water tables, waterlogging, or drought.
“Jarrah is a species that is very susceptible to waterlogging and also to attack by Phytophthora disease,” Batini explained. “Widespread, mass collapse of jarrah and understorey species was observed from 1940 to 1970, mostly in waterlogged gully head sites during a long period of very high rainfall. At the same time, bullich was expanding into some of these sites, with pole‑ and pile‑sized bullich trees now growing among large jarrah stumps. These changes are consistent with a sustained period of higher rainfall, raised water tables, and waterlogging.”
“Based on my observations, long‑term rainfall records, monitoring of vegetation response for over 50 years and tree‑ring analyses,” he said, “the jarrah forest is resilient, and the very small number of recent tree deaths are natural changes as a result of multi‑decadal rainfall cycles that may be wetter or drier than average.”
The findings suggest that while drought events can cause localised damage, the jarrah ecosystem may be better equipped to withstand climatic variability than previously thought — a conclusion that must influence the state government’s future management of the forest. "
https://woodcentral.com.au/jarrah-forests-not-on-brink-of-collapse-study-dispute...