Stirling experts inform new study on world’s tropical forests

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Extensive research on tropical forests in Central Africa – conducted by the University of Stirling over several decades – forms part of an important new paper published in a prestigious journal.

Professor Lee White, Honorary Professor, and Dr Kathryn Jeffery, Researcher, both of the Faculty of Natural Sciences, are part of a global collaboration that compiled data for the study, ‘Long-term thermal sensitivity of Earth’s tropical forests’, published in Science.

The world’s tropical forests store a quarter-century worth of fossil fuel emissions in their trees and there are fears that global warming could reduce this store – if tree growth reduces, or death increases – accelerating climate change.

The new research measured carbon storage in more than half-a-million trees in 813 forests across the tropics – and found that they can continue to store large amounts of carbon under high temperatures. However, the team – from many institutions across the globe – reported that forests would only continue to store high levels of carbon in a warmer world if they have time to adapt, remain intact and if global warming is strictly limited – to avoid pushing global temperatures into conditions beyond the crucial threshold.

The study also illustrates that African rainforest is much more resilient to warming than the Amazon – a finding mirrored in a Nature paper, involving Professor White, Dr Jeffery, and Stirling’s Professor Kate Abernethy, published earlier this year.

Expert checks tree growth

The University of Stirling have been working in Gabon since the 1980s.

Zoologist and conservationist Professor White has been conducting research in Gabon since 1989.

He said: “The sensitivity of tropical forests to the climate – specifically the effects of short-term drying and warming – is a key uncertainty in predicting global climate change. This study shows that tropical forests are resistant to small temperature differences – and they can continue to store large amounts of carbon in a warmer world, but only if countries limit greenhouse gas emissions.

“This publication, along with our recent Nature paper, uses some of our long-term data and critically illustrates that the African rainforest is proving much more resilient to climate change, compared to those in the Amazon.

“University of Stirling scientists have been working in Gabon for the past 40 years and our work is making a difference in informing key changes that are happening to the planet. This important study will help inform future research in this area.”

Kathryn Jeffery
The paucity of the data from Central Africa’s forests – compared to those in South America – means that Stirling’s contribution to maintaining these plots for global comparison is hugely important.
Dr Kathryn Jeffery Researcher

The University of Stirling scientists have conducted research in Lopé National Park, Gabon, since 1979 – collecting data on its trees, and their carbon storage credentials, for decades.

The new study is the first to analyse long-term climate sensitivity, based on direct observation of whole forests across the topics. It suggests that, over the long-term, temperature has the greatest effect on forest carbon stocks by reducing growth, with drought killing trees the second factor.

The research team conclude that tropical forests have long-term capacity to adapt to some climate change, in part because of their high biodiversity, as tree species better able to tolerate new climatic conditions grow well and replace less well-adapted species over the long-term. However, maximising this potential climate resilience depends on keeping forests intact.

Dr Jeffery – who was based full-time in Gabon between 2004 and 2017 – said: “This study is the product of a global collaboration – one that Stirling researchers have been underpinning for four decades, with our long-term forest ecology programme at Lopé. It has now expanded to a permanent network of more than 300 forest plots across the whole of Gabon.

“The paucity of the data from Central Africa’s forests – compared to those in South America – means that Stirling’s contribution to maintaining these plots for global comparison is hugely important.”

Supersite

The Nature paper, published in March, found that the ability of the world’s tropical forests to remove carbon from the atmosphere is decreasing. The research – which tracked 300,000 trees over 30 years – revealed that a feared switch of the world’s undisturbed tropical forests from a carbon sink to a carbon source has begun.

Professor Abernethy, who runs Stirling’s Tropical Ecology Research Group, said: “Stirling continues to manage the prestigious Lopé National Park ecological research site, which has produced several of the largest and longest-running ecological datasets in Africa and was recently advocated as a ‘supersite’ for data relevant to evaluating the impacts of climate change in rainforests.

“Our multidisciplinary programme provides a rigorous, empirical evidence-base to improve their sustainable management.”

The Science and the Nature papers were both led by the University of Leeds and involved many global partners.

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