Acacia tree in front of Mount Kilimanjaro in Kenya
Uğur OKÇu/iStockphoto/Getty Images
High-resolution satellite imagery is being used to map every tree in Africa, demonstrating a technique that can help improve monitoring of deforestation around the world.
Florian Reiner and his colleagues at the University of Copenhagen in Denmark used imagery from satellites operated by the US company Planet and machine learning models to map forest canopy cover across the African continent.
Modern satellites typically capture tree canopies with a resolution of 30 meters. This is good for measuring forest size, but not so good for mapping individual trees or small bushes.
The satellite data used by Reiner and his colleagues had a resolution of 3 meters, so the study was able to map all the trees, even those that were not part of the forest.
The results suggest that 30% of all trees in Africa are scattered across farmlands, savannahs and urban areas, rather than in forests.
Many African countries lack dense forests, but there are still plenty of trees, says Reiner. “These trees are very important to the local ecosystem, people and economy.”
A similar study across Europe revealed that up to 24% of tree cover is outside forests in some countries.
By tracking every tree or bush, researchers can begin to monitor how these trees are coping with climate change or whether they are vulnerable to deforestation, Reiner said. say. It can also improve monitoring of tree planting activities, an increasingly popular method of removing carbon dioxide from the atmosphere.
John Francis of the Alan Turing Institute in London said:
Reiner says the research is a proof of concept, not a ready-to-use map for commercial use. “It’s a research position. It shows what can be done,” he says.
But he’s already working with colleagues to extend the tracking approach to cover the entire canopy.
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