Data from Copernicus Sentinel-2 have enabled scientists to study global forests in greater detail, a new study shows. By focusing on the top layer of forests – an area commonly known as the forest canopy – researchers found that some forests were less resilient to environmental stress than others.
“We are worried about the vulnerability of our ecosystems to threats like climate change,” explains Jesús Aguirre-Gutiérrez, from the University of Oxford, and lead-author of the paper. “To study what makes trees resilient in tropical forests, we need to look closely at their traits, things like leaf chemistry, shape, and structure.”
Predicted distribution of leaf thickness and wood density in forests in the Americas, Africa, and Asia
Copyright:Contains modified Copernicus Sentinel data 2025/processed by ESA and Jesús Aguirre-Gutiérrez
Variables like the amount of water in leaves, their shape, or even their nitrogen content all help scientists understand how trees react to different climates. A tree that has smaller and thicker leaves might be less efficient to carry out photosynthesis, for example, while trees with thicker leaves might be better at conserving nutrients for themselves.
Aguirre-Gutiérrez and his team have been working on understanding these traits by sampling trees directly and measuring these variables in a lab. But in order to get a holistic view of an entire forest, they needed to take bigger steps – and this is where satellite data came into play.
“Over the past few years, we’ve been working to understand how the traits we measure in the field relate to remote sensing, to help us scale up,” he explains. “By looking at the spectral signatures of the canopy of trees, we’ve built models that let us map out the distribution of trait composition across larger areas.”
Predicted distribution of leaf area in forests in the Americas, Africa, and Asia
Copyright:Contains modified Copernicus Sentinel data 2025/processed by ESA and Jesús Aguirre-Gutiérrez
In his recent study published in Nature, Aguirre-Gutiérrez used data on tree traits from more than 1800 vegetation plots in tropical forests across the Americas, Africa and Asia. They combined these samples with data from the Copernicus Sentinel-2 mission.
Sentinel-2 of the European Union’s Copernicus Earth Observation Programme covers 13 spectral channels, with high spatial resolution and with a revisit period of five days. This enabled researchers to scale functional traits, such as leaf morphology and water content without them having to sample each tree locally.
Copernicus Sentinel-3 over ocean and ice
Copyright:ESA
The team focused on leaf traits in the upper canopy, the main interface between forests and the atmosphere. These traits are important in processes like transpiration and photosynthesis. Additionally, since they are located at the top of the trees, they can be directly detected using spectral remote sensing.
The results suggest that tropical American forests appear to be significantly more diverse in terms of tree traits than tropical Asian and African forests, with the latter having fewer tree species. This has direct implications on the resilience of forests to climate change and other threats in general.
“When you have a forest with lots of species that each have different traits, there's a better chance that some of them will be able to handle changes. If it suddenly gets hotter or drier, some species might struggle or even die, but others might be well-suited to those new conditions,” Aguirre-Gutiérrez says.
On the other hand, if the forest has fewer species and a narrower range of traits, then when the climate shifts, it is much more likely that many of them won’t make it. “That leaves you with only a few species that can persist, and over time, the ecosystem becomes more homogeneous. Less biodiversity means less resilience and the whole system is more vulnerable to future stresses,” he adds.
Satellite image of forests in Côte d'Ivoire, western Africa
Copyright:Contains modified Copernicus Sentinel-2 data (2024)/ processed by ESA
Understanding what makes one forest more resilient than another is important for many reasons. These models could assist researchers identify priority areas for further field data collection, especially across tropical forests in Africa and Asia, where fewer data are available. The findings can also support global vegetation models and inform conservationists and leaders on which ecosystems might need more support in the face of climate change and other threats.
“When we think about tropical forests, we think that all forests are the same.” Aguirre-Gutiérrez concludes. “With these results, we’re seeing that actually that is not the case and therefore we need to pay close attention and conserve each one of them.”
About the Copernicus Sentinels
The Copernicus Sentinels are a fleet of dedicated EU-owned satellites, designed to deliver the wealth of data and imagery that are central to the European Union's Copernicus environmental programme.
The European Commission leads and coordinates this programme, to improve the management of the environment, safeguarding lives every day. ESA is in charge of the space component, responsible for developing the family of Copernicus Sentinel satellites on behalf of the European Union and ensuring the flow of data for the Copernicus services, while the operations of the Copernicus Sentinels have been entrusted to ESA and EUMETSAT.
Did you know that?
Earth observation data from the Copernicus Sentinel satellites are fed into the Copernicus Services. First launched in 2012 with the Land Monitoring and Emergency Management services, these services provide free and open support, in six different thematic areas.
The Copernicus Land Monitoring Service (CLMS) provides geographical information on land cover and its changes, land use, vegetation state, water cycle and Earth's surface energy variables to a broad range of users in Europe and across the World, in the field of environmental terrestrial applications.
It supports applications in a variety of domains such as spatial and urban planning, forest management, water management, agriculture and food security, nature conservation and restoration, rural development, ecosystem accounting and mitigation/adaptation to climate change.
The Copernicus Climate Change Service (C3S) supports society by providing authoritative information about the past, present and future climate in Europe and the rest of the World.
References:
Aguirre-Gutiérrez, J., Rifai, S.W., Deng, X. et al. Canopy functional trait variation across Earth’s tropical forests, Nature, https://doi.org/10.1038/s41586-025-08663-2, 2025.