Tropical forests are struggling to keep pace with climate change

Tropical rainforests help the planet breathe. They store carbon, control temperatures, and shelter wildlife. These tropical forests have survived climate changes for millions of years, but now they face an unprecedented challenge.

Climate change is reshaping ecosystems at an unprecedented pace. Rising temperatures, shifting rainfall patterns, and extreme weather events are placing immense stress on forests across the Americas.

Tropical forests in a shifting climate

A new study reveals that these forests are not adapting quickly enough to keep up with environmental changes. This slow response raises concerns about their long-term survival and the cascading effects their decline could have on the global climate system.

Dr. Jesús Aguirre-Gutiérrez from the University of Oxford’s Environmental Change Institute led the research with over 100 scientists and local collaborators.

The team analyzed data from 415 permanent forest plots, covering regions from Mexico to southern Brazil.

By studying the characteristics of more than 250,000 trees, they examined how different species are responding to shifting temperatures and rainfall patterns.

Trees are adapting too slowly

The experts found that while climate change alters temperature and rainfall, tree communities are not keeping up with the pace.

This slow response threatens the balance of these ecosystems. Some species thrive, while others struggle. Traits like wood density, leaf thickness, and drought resistance play a crucial role in determining which trees survive.

“Tropical forests are among the most diverse ecosystems on Earth, yet their ability to adapt to climate change is limited. Understanding which traits help trees survive can guide conservation efforts and policy decisions,“ said Dr. Aguirre-Gutiérrez.

“Given the changes in climate we have observed over the last 40 to 50 years, you might think there have also been lots of changes in the tree communities in tropical rainforests. But some of these changes are too small and too slow to actually adapt to the observed changes in climate.”

By looking at individual trees from different communities, the team found that some have suffered due to climate shifts, while others have thrived, noted Dr. Aguirre-Gutiérrez.

“We can study the characteristics, also known as ‘tree traits,’ of those that have survived, as well as new individuals joining the communities and those that have died, to understand what makes them react differently to a changing climate.”

Risky future for rainforests

Mountainous forests appear to adapt faster than lowland forests. This difference likely results from the greater climate variability at higher altitudes.

Meanwhile, younger trees exhibit noticeable shifts in traits, yet overall forest composition remains largely unchanged.

By 2100, the region’s temperatures could rise by up to 4°C, with rainfall decreasing by as much as 20%. These changes may push tropical forests further out of balance, making them more vulnerable to extreme climate events. Without intervention, the risk of ecosystem collapse increases.

“If we know what species of trees are doing better or worse, and what set of traits they have, then we know what they can withstand. It will help inform what conservation actions should be encouraged and where funding should be allocated,” said Dr. Aguirre-Gutiérrez.

Extensive collection of field data

Professor José Javier Corral Rivas from the Juarez University of the State of Durango (UJED) highlighted the significance of long-term field studies.

“It is thanks to the extensive collection of field data over the past decades, largely supported by Latin American institutions and international collaborations, that we are able to make discoveries like this one, particularly in highly biodiverse regions such as the tropical forests of the Americas.”

Professor Oliver Phillips from the University of Leeds emphasized the importance of human effort in this research.

“What is remarkable is that we discovered this not with satellites or artificial intelligence, but by the efforts of botanists, foresters and hundreds of other skilled partners,” noted Professor Phillips. “These undervalued colleagues provide a great service to the world.”

Climate response of tropical forests

The researchers found that functional traits among trees are shifting but at a pace far too slow to match climate change. Deciduous species are becoming more common in some forests, and leaf thickness is decreasing.

However, the rate of change is only a fraction of what is needed for trees to maintain equilibrium with the changing environment.

Lowland forests, which are experiencing higher temperature increases and greater drought stress, are showing stronger changes than montane forests. While some species are adapting, others are dying at increasing rates.

The experts found that tree recruitment, where young trees replace older ones, is the most responsive to climate shifts. However, these recruits still track climate change at only about 22% of the expected rate.

Protecting rainforests for future generations

“Measuring forests carefully tree-by-tree, species-by-species and year-after-year, teaches us about the health of trees and the risks they face,“ noted Professor Beatriz Marimon from the State University of Mato Grosso, Brazil.

“In some of our Amazon plots the forest is facing a deadly combination of fire, heat and drought. Understanding which tree species can survive these threats is critical to creating a liveable future for all of us.”

This study highlights the urgent need for research and conservation efforts to help tropical forests withstand climate challenges. Without immediate action, these ecosystems may struggle to survive the coming decades.

The study is published in the journal Science.

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