How do you assess the health of the world’s forests?
Forests have a crucial role to play in sequestering carbon, but how can we tell how healthy a forest is and how it’s responding to climate change?
A first-of-its-kind pilot initiative, led by UCL researchers, is taking highly detailed 3D scans of dense tropical rainforest using drones and lasers to help track how the forests are changing due to climate change.
Tracking change with modern technology
The ForestScan project is part of the international initiative GEO-TREES, which is building a global network of forest reference sites where scientists can precisely measure trees and forest structure. These sites, known as Forest Biomass Reference Measurement Sites (FBRMS), will help scientists better understand how much biomass forests contain – which provides an indication of how much carbon is stored across the entire forest – and track how forests are responding to climate change.
Researchers measured representative plots totalling nearly 550 hectares in three tropical rain forested regions: Paracou in northern French Guiana, Lopé National Park in central Gabon and Kabili-Sepilok Forest Reserve in northeast Malaysia.
Laser scanners created 3D models of over 200,000 individual trees across the selected plots from below the canopy using Terrestrial Laser Scanning (TLS), and from above using Uncrewed Aerial Vehicle Laser Scanning (UAV-LS) – drones equipped with lasers that fly over the forest – and Airborne Laser Scanning (ALS) aboard planes. At each site, local scientists also gathered more detailed data by hand-measuring, tagging and ground scanning about 7,000 trees in sub-divisions within these plots
“Accurate forest biomass data is essential for understanding how forests store carbon and respond to climate change,” explained Dr Cecilia Chavana-Bryant. “By combining advanced 3D scanning technologies across three continents, we’ve created one of the most detailed datasets ever collected for tropical forests – providing a benchmark for satellite missions and Earth observation tools.”
Chavana-Bryant says the work lays the foundation for more reliable global forest monitoring, helping scientists, policymakers, and conservationists make informed decisions about protecting forests and tackling climate change at both local and global scales.
Soaking up the carbon
Forests play a key role in absorbing atmospheric carbon dioxide; as they grow, they store the greenhouse gas in their trunks and branches, and around half of a tree’s living mass is made up of carbon drawn from the atmosphere.
Measuring forest biomass gives an indication of the quantity of stored carbon, which is especially important for the emerging carbon offset market and to help researchers estimate the amount of carbon released due to fire or illegal logging. The uncertainty about carbon offsetting comes mainly from insufficient reliable ground data to train the deep learning and AI models that are often used to forecast forest carbon levels.
Professor Mat Disney said: “Forests are critical for way more than just carbon of course, but it is a crucial aspect of the efforts to raise investment to help preserve and protect them. We really need more accurate data on how much carbon is sequestered away within them.”
Disney says ForestScan is critical to developing “more accurate satellite maps to assess the health of our forests around the world, and their ongoing capacity to mitigate carbon dioxide levels globally. Seeing how many people have accessed the data from all over the world already is incredible and shows how important these data will be.”
News reference
ForestScan: a unique multiscale dataset of tropical forest structure across 3 continents including terrestrial, UAV and airborne LiDAR and in-situ forest census data, Earth System Science Data, 2026. Chavana-Bryant, C., et al.