Australia’s mountain ash forests, found in southeastern Australia, are slowly losing trees due to rising temperatures caused by climate change.
Mountain ash trees can store more carbon per hectare than even the Amazon rainforest. Their decline affects not just Australia but the global climate.
New research led by Prof Lindenmayer and others shows that as temperatures rise, these forests are able to support fewer trees. For every 1°C rise, number of trees can drop by 9%.
By 2080, if temperatures increase by 3°C (as predicted), these forests may lose 25% of their trees, which also means a major loss of stored carbon.
Higher temperatures draw more moisture from the soil and leaves. This makes it harder for trees, especially smaller ones or those in the shade, to get the water they need.
In all forests, trees compete for sunlight, water, and nutrients. Naturally, some trees die off over time. But warming makes this process faster and more severe.
While tree loss usually happens slowly, extreme events like droughts or heatwaves can cause sudden die-offs.
Scientists studied over 1,300 measurements from more than 100 forest plots in Victoria’s Central Highlands, collected between 1947 and 2000.
"Carrying capacity" is the number of trees an area can support. In warmer and drier conditions, that capacity drops, meaning fewer trees can survive.
Healthy forests normally absorb more carbon than they release. But when tree deaths increase, forests can start releasing more carbon than they store, worsening climate change.
By 2080, these forests could release over 100 million tonnes of stored carbon. That’s like a million cars each driving 10,000 km a year for 75 years.
Massive tree-planting efforts are needed to fight climate change. But the study warns: we must consider how many trees forests can support in a warmer future, not just today.
While we can’t stop global warming instantly, we can help forests cope. One method is ecological thinning, removing some trees so the remaining ones get more water and nutrients.
Read more at Phys.org.
Research published in Nature Communications.