Study finds Amazon trees growing bigger despite climate change | National

By Stephen Beech

Trees are growing even bigger in the Amazon rainforest – despite climate change, reveals new research.

Average tree size across the world’s largest tropical rainforest has increased by 3.2% every decade for the last 30 years – consistent with a response to rising carbon dioxide levels, say scientists. 

The international team of researchers said their findings show the “remarkable resilience” of the forest.

The team of almost 100 scientists monitored the size of trees in 188 permanent plots and discovered that the increase has continued for at least 30 years. 

The study, published in the journal Nature Plants, is the result of a partnership involving more than 60 universities in South America and beyond – including the Universities of Birmingham, Bristol, and Leeds in Britain.

Co-author Professor Beatriz Marimon, from Universidade do Mato Grosso, Brazil, said: “This is a good news story.

“We regularly hear how climate change and fragmentation is threatening Amazonian forests.

“But meanwhile the trees in intact forests have grown bigger; even the largest trees have continued to thrive despite these threats.” 

The study found that both large and smaller trees have increased in size, consistent with benefitting from fertilization by increased atmospheric carbon dioxide.  

Joint lead author Dr. Adriane Esquivel-Muelbert, from the University of Cambridge, said: “Ahead of COP30 in Brazil later this year, these results underscore just how important tropical rainforests are in our ongoing efforts to mitigate against man-made climate change.  

“Large trees are hugely beneficial for absorbing CO2 from the atmosphere and this study confirms that.

“Despite concerns that climate change may negatively impact trees in the Amazon and undermine the carbon sink effect, the effect of CO2 in stimulating growth is still there.

“This shows the remarkable resilience of these forests, at least for now.” 

Joint lead author Dr. Rebecca Banbury Morgan, from the University of Bristol, said: “Our paper also highlights how destructive Amazon deforestation really is.

“Large tropical trees are hundreds of years old.

“We can’t simply plant new trees and expect them to confer anything like the kinds of carbon or biodiversity benefits that the old, natural forest is providing.” 

Previous research has shown that the Amazon rainforest plays a “key” role in taking up carbon which would otherwise be in the atmosphere. 

Study joint senior author Professor Tim Baker, from the University of Leeds, said:  “We knew that the total amount of carbon stored in the trees of intact Amazonian forests has increased.

“What this new study shows is that all sizes of tree have grown larger over the same period – the whole forest has changed.”

The study is the first of its kind to measure how increases in CO2 have systematically changed the tree size structure of Amazon forests.

The researchers noted that as the biggest trees have grown larger, they have managed to increasingly dominate competition for resources.  

Professor Oliver Phillips, also of the University of Leeds, added: “What happens to big trees – including how they deal with increasing climate threats and manage to disperse their seeds – is now mission-critical.

“The only way the giants will stay healthy is if the Amazon ecosystem stays connected.

“Deforestation is a huge threat multiplier and will kill them if we let it.”