Victoria’s mountain ash forests could lose a quarter of giant trees as temperatures rise

Victoria’s mountain ash forests are thinning rapidly as the globe heats up, and could lose a quarter of their “giant” trees that grow up to 80m tall in the coming decades, research has found. Forests of Eucalyptus regnans – one of the tallest tree species in the world – lose about 9% of their trees for every degree of warming, according to a University of Melbourne-led study published in Nature Communications.

“These are giants,” said lead author Dr Raphael Trouve. “They are the tallest flowering plant on Earth – that means they regularly reach 60 to 80m tall.”

The researchers analysed data collected from mountain ash forests over more than 50 years to determine tree mortality rates and forest carrying capacity – the maximum number of trees of a given size that the forest can sustain. They found that forests growing in the warmest conditions had the lowest carrying capacity, which further decreased with rising temperatures.