State of the art and perspectives for remote sensing monitoring of carbon dynamics in African tropical forests

Thomas Bossy ^1,2,3* Philippe Ciais ^2,4 Solène Renaudineau ³ Liang Wan ² Bertrand Ygorra ³ Elhadi Adam ⁵ Nicolas Barbier ⁶ Marijn Bauters ⁷ Nicolas Delbart ^8,9 Frédéric Frappart ³ Tawanda Winmore Gara ¹⁰ Eliakim Hamunyela ¹¹ IFO Suspense Averti ¹² Gabriel Jaffrain ¹³ Philippe Maisongrande ¹⁴ Maurice Mugabowindekwe ^15,16 Theodomir Mugiraneza ^16,17 Cassandra Normandin ³ Conan Vassily Obame ¹⁸ Marc Peaucelle ³ Camille Pinet ¹³ Pierre Ploton ⁶ Le Bienfaiteur Sagang ¹⁹ Martin Schwartz ² Valentine Sollier ³ Bonaventure Sonké ^20,21 Paul Tresson ⁶ Aurélien De Truchis ²² An Vo Quang ¹³ Jean-Pierre Wigneron ³

• ¹ Université de Versailles Saint-Quentin-en-Yvelines, Versailles, France
• ² UMR8212 Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Gif-sur-Yvette, Île-de-France, France
• ³ Interactions sol-plante végétale (ISPA UMR), Villenave-d'Ornon, France
• ⁴ CEA Saclay, Gif-sur-Yvette, Île-de-France, France
• ⁵ University of the Witwatersrand, Johannesburg, South Africa
• ⁶ UMR5120 Botanique et modélisation de l'architecture des plantes et des végétations (AMAP), Montpellier, Languedoc-Roussillon, France
• ⁷ Q-ForestLab, Laboratory of Quantitative Forest Ecosystem Science, Department of Environment, Ghent, Belgium
• ⁸ Université Paris Cité, Paris, Île-de-France, France
• ⁹ UMR8236 Laboratoire Interdisciplinaire des Energies de Demain (LIED), Paris, Île-de-France, France
• ¹⁰ Department of Environmental Science and Management, California State Polytechnic University Humboldt, Arcata CA, United States
• ¹¹ Department of Environmental Science, School of Science, Faculty of Agriculture, Engineering and Natural Sciences, University of Namibia, Windhoek, Namibia
• ¹² Marien Ngouabi University, Brazzaville, Republic of Congo
• ¹³ Institut National de l’information Géographique et Forestière (IGN), ParisSaint-Mandé, France
• ¹⁴ Centre National d’Etudes Spatiales (CNES), Paris, France
• ¹⁵ Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
• ¹⁶ Centre for Geographic Information Systems and Remote Sensing, College of Science and Technology, University of Rwanda, Kigali, Rwanda
• ¹⁷ Cadasta Foundation, Washington DC, United States
• ¹⁸ Agence Gabonaise d'Etudes et d'Observations Spatiales (AGEOS), Libreville, Gabon
• ¹⁹ Institute of the Environment and Sustainability, College of Physical Sciences, University of California, Los Angeles, Los Angeles, California, United States
• ²⁰ Higher Teacher Training College (HTTC), Yaounde, Cameroon
• ²¹ Plant systematics and Ecology Laboratory, University of Yaoundé, Yaoundé, Cameroon
• ²² kayrros SAS, Paris, France

African tropical forests play a crucial role in global carbon dynamics, biodiversity conservation, and climate regulation, yet monitoring their structure, diversity, carbon stocks and changes remains challenging. Remote sensing techniques, including multi-spectral data, lidar-based canopy height and vertical structure detection, and radar interferometry, have significantly improved our ability to map forest composition, estimate height and biomass, and detect degradation and deforestation features at a finer scale. Machine learning approaches further enhance these capabilities by integrating multiple data sources to produce improved maps of forest attributes and track changes over time. Despite these advancements, uncertainties remain due to limited ground-truth validation, and the structural complexity and large spatial heterogeneity of African forests. Future developments in remote sensing should examine how multi-sensor integration of high-resolution data from instruments such as Planet, Tandem-X, SPOT and improved AI methods can refine forest composition, carbon storage and function maps, enhance large-scale monitoring of tree height and biomass dynamics, and improve forest degradation and deforestation detection down to tree level. These advancements will be essential for supporting science-based decision-making in forest conservation and climate mitigation.