Overview

• A University of Melbourne–led analysis of roughly five decades of plot data finds mountain ash forests lose about 9% of trees for each 1°C of warming.
• Researchers conclude warming could turn these forests from major carbon sinks into net sources as mortality and decay release stored carbon.
• The mechanism identified is intensified competition for scarce water, with larger trees outcompeting smaller ones under heat stress.
• Projections to 2080 are based on approximately 3°C of warming and do not include bushfire impacts that scientists expect to worsen.
• The authors propose selective thinning to reduce stand density, with implications for drought resilience and Melbourne’s water supply.