Trees across the Amazon rainforest are growing larger in response to rising levels of carbon dioxide in the atmosphere, according to a major new study.
The research, published in the Nature Plants journal, found that the average size of trees in the Amazon has increased by 3.2 per cent every decade for at least the past 30 years.
Scientists say the trend is consistent with the fertilising effect of higher concentrations of CO2, which can boost plant growth.
The findings come from the RAINFOR network, an international partnership of more than 60 universities in South America, the UK and elsewhere, including the Universities of Birmingham, Bristol and Leeds. Almost 100 scientists monitored trees across 188 permanent forest plots to build the long-term dataset.
Professor Beatriz Marimon, from Universidade do Mato Grosso in Brazil, who coordinated much of the data collection in southern Amazonia, 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.”
Both large and smaller trees were found to be increasing in size, pointing to a widespread response to higher carbon dioxide levels in the atmosphere.
Dr Adriane Esquivel-Muelbert, from the University of Cambridge and joint lead author of the paper, said the results highlight the vital role of rainforests in tackling climate change.
She 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.”
But researchers warned that the apparent benefits of CO2 should not obscure the damage caused by deforestation.
Dr Rebecca Banbury Morgan, from the University of Bristol and also a joint lead author, 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.”
Professor Tim Baker, from the University of Leeds and joint senior author, added: “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.”
