LIDAR remote sensing
Above-groundbiomass
Space remote sensing
Flux measurement
Biodiversity
Victoria Hippolyte IYABO
Elie Chrisnel NZIGOU DOUBINDOU
Carmel MOUNZIEGOU-MOUNZIEGOU
Yann IBINGA-BOUASSA
Ninon BESSON
Thomas BOUDRAS
Abel Bridet MOUYABI NTOYO
Maurice BAKALA NKAYA
Samuel Anthony KAYES
Emmafie Jinelle BONDA
Grace Martine BOBANGUI
Frejusse Fourier MIASSOUKA MILANDOU
Diel Jofrés MIHINDOU
Claude Evny MAGANGA MOUSSADJI
Wetlands
Human and social sciences
France PhD
Gabon PhD
Congo PhD
Yann IBINGA-BOUASSA
Estimation and spatialization of carbon stock dynamics and sequestration strategies in Gabon
PhD dates : March 2026 - February 2029 Supervisors : Pr. MEDZA MVE Samson Daudet and Dr. CIAIS Philippe Host institution : Université des Sciences et Techniques de Masuku (USTM)
Partners institutions : Agence Gabonaise d'Etudes et d'Observations Spatiales (AGEOS) and Laboratoire des Sciences du Climat et de l'Environnement (LSCE) under the supervision of Commissariat à l'Energie Atomique (CEA)
Gabon's forests cover more than 85% of the country. They are among the world's largest reserves of carbon and biodiversity. Their preservation depends on a thorough understanding of their ecological functioning and continuous monitoring of biodiversity and carbon stocks. To analyze forest dynamics and their effects on climate change, it is crucial to obtain accurate estimates of biomass and carbon stocks. These data are essential for guiding public policies aimed at reducing greenhouse gases and supporting international initiatives such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation). The aim of this project is to develop an innovative and replicable methodology based on deep learning, forest inventory data, and multi-source remote sensing (satellites and drones). Traditional approaches to assessing carbon stocks rely on semi-automated analysis of satellite images and data from forest inventory campaigns. These approaches remain time-consuming and limited in their spatial scope. The integration of emerging technologies, particularly artificial intelligence (AI) combined with multi-source data, opens up new possibilities.
Carmel MOUNZIEGOU-MOUNZIEGOU
Regional analysis of vegetation types and forests in Gabon and the Congo Basin through the integration of heterogeneous sources and models
PhD dates : March 2026 - February 2029 Supervisors : Dr. MAMBIMBA Aboubakar, Dr. COUTERON Pierre and Dr. BARBIER Nicolas Host institution : Joint Research Unit for botAnique et Modélisation de l'Architecture des Plantes et des végétations (UMR AMAP) under the supervision of Institut de Recherche pour le Développement (IRD) and Centre de coopération internationale en recherche agronomique pour le développement (CIRAD)
Partners institutions : Agence Gabonaise d'Etudes et d'Observations Spatiales (AGEOS) and Institut de recherche en Ecologie Tropicale (IRET) attached to Centre national de la recherche scientifique et technologique (CENAREST)
This thesis project aims to improve detailed mapping of vegetation types, which is essential for studying biodiversity and the carbon cycle, as current maps are inaccurate (10 km resolution) and based on limited and heterogeneous data. To produce more robust maps, it relies on the integration of multiple remote sensing sources (optical, RADAR, LiDAR, drone) combined with field observations, and uses vegetation models and multimodal deep learning approaches, including self-supervised learning, to improve model performance under varied acquisition conditions. The objectives include developing a reliable methodology, building a diverse training dataset, co-constructing a typology validated by experts, producing national and regional reference maps, and validating them with a spatialized estimate of the reliability of the cartographic products.
Maurice BAKALA NKAYA
Macro- and microscopic responses of commercial and secondary forest species in Congo forests to environmental change
PhD dates : January 2026 - December 2028 Supervisors : Dr. MAKOUANZI EKOMONO Chrissy Garel and Pr. CHAIX Gilles
Host institution : Institut National de Recherche Forestière (IRF)
Partners institutions : Université Marien Ngouabi (UMNG), Joint Research Unit Amélioration génétique et adaptation des plantes méditerranéennes et tropicales (UMR AGAP) under the supervision of Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) This project focuses on understanding, through experimentation, the adaptation strategies of commercial and secondary forest species in Congo in the face of global environmental change. It contributes to a better understanding of the natural regeneration of species of interest. Its goal is to analyze the responses of these species to changes in light intensity and water regime, both at the macroscopic level (initial growth, plant architecture, leaf traits) and the microscopic level (cell structure, hyperspectral imaging). The methodology revolves around collecting seeds from commercial and secondary species in Congolese forests, testing them in nurseries under controlled conditions, and analyzing the data on two scales: macro and microscopic. An analysis of the trade-offs between characteristics depending on environmental conditions will provide insight into the adaptation strategies developed by species in terms of architecture, anatomy (tissue structure), biochemistry, etc. The expected results aim to provide an understanding of the mechanisms by which commercial and secondary forest species in Congo adapt to environmental change. They will inform conservation and sustainable forest management policies by identifying the most vulnerable species. This project will contribute to a better understanding and preservation of Congolese forest biodiversity and the sustainability of the ecosystem services it provides.
Thomas BOUDRAS
Self-supervised deep learning approaches for high-resolution reconstruction of biomass carbon storage variations in African equatorial forests
PhD dates : December 2025 - November 2028 Supervisors : Dr. CIAIS Philippe, Dr FAYAD Ibrahim and Dr. WIGNERON Jean-Pierre Host institution : Laboratoire des Sciences du Climat et de l'Environnement (LSCE) under the supervision of Université Versailles-Saint-Quentin-en-Yvelines (UVSQ)
Partners institutions : Joint Research Unit Interactions Sol Plante Atmosphère (UMR ISPA) under the supervision of Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE)
Equatorial tropical forests play a major role in the global carbon cycle and the preservation of biodiversity, but remain highly susceptible to anthropogenic (fires, degradation, deforestation) and climatic disturbances. The main objective of this thesis is to develop a self-supervised learning (SSL) model capable of processing time series of satellite images to detect and quantify forest changes and biomass variations in African equatorial forests. To do this, we will integrate:
- Multi-temporal Sentinel images.
- High-resolution biomass maps from the OFVi initiative.
- Archives of forest disturbances derived from Landsat series.
- Future data from NISAR and Biomass satellites, subject to availability.
The SSL model will be trained without explicit labels in order to automatically learn robust spatial and temporal representations of forest dynamics. These results will be validated using national inventories and reference data before generating annual carbon balance maps. The proposed methodology thus combines advances in deep learning, remote sensing, and carbon accounting.
Abel Bridet MOUYABI NTOYO
Understanding carbon dynamics in Loundoungou (northern Congo) by integrating drone and field data
PhD dates : January 2026 - December 2028 Supervisors : Dr. BOCKO Yannick and Dr. GARCIN Yannick
Host institution : Faculté des Sciences et Techniques (FST) attached to Université Marien Ngouabi (UMNG) and Joint Research Unit botAnique et Modélisation de l'Architecture des Plantes et des végétations (UMR AMAP) under the supervison of Institut de Recherche pour le Développement (IRD)
Partners institutions : Congolaise Industrielle des Bois (CIB-OLAM)
This thesis project aims to improve our understanding of carbon dynamics in the tropical forests of Central Africa, a crucial issue for anticipating ecosystem responses to global change. Despite their major role in the carbon cycle, current estimates of carbon stocks and fluxes remain highly uncertain, particularly due to the difficulty of measuring tree productivity and mortality on a large scale. The study site, the Loundoungou Observatory (northern Republic of Congo), is a unique “super-site” combining intensive forest inventories with regular acquisitions by drones and LiDAR. The project adopts a multi-scale approach integrating field data, functional trait measurements, monitoring of non-arboreal life forms (lianas, giant herbaceous plants), and high-resolution aerial imagery to understand forest carbon dynamics at this site. This thesis project is structured around three main areas: (1) predicting tree productivity based on available light, functional traits, and biotic interactions; (2) detecting early signs of mortality and quantifying the impact of disturbances, including rare ones, on carbon stocks at the landscape scale; (3) assessing the role of understory vegetation and regeneration in forest dynamics according to biotic and abiotic contexts. This work will yield important findings on the biotic and abiotic determinants of carbon dynamics in dense African forests, with direct implications for vegetation modeling and climate policies such as REDD+. It will also strengthen local capacities in forest ecology and remote sensing through a close partnership between Marien Ngouabi University, IRD, and the forestry company CIB-OLAM.
Claude Evny MAGANGA MOUSSADJI
Coexistence between forest elephants and local communities in Gabon: the role of ecological factors and tolerance in conflict dynamics and mitigation
PhD dates : February 2026 - January 2029 Superviros : Pr. WALI WALI Christian, Pr. NTIE Stephan, Dr. BOURGEOIS Stéphanie, Pr. ROBERT Alexandre and Dr. SIGAUD Marie Host institution : Agence Nationale des Parcs Nationaux (ANPN)
Partners institutions : Université Omar Bongo (UOB) and Centre d'écologie et des sciences de la conservation (CESCO) under the supervision of Muséum National d'Histoire Naturelle (MNHN)
This thesis project explores the coexistence between forest elephants (Loxodonta cyclotis) and local communities in Gabon. Faced with an upsurge in human-wildlife conflicts, particularly related to agricultural damage and human losses caused by elephants, this research aims to understand the ecological and social factors that influence these dynamics. Gabon, home to more than 70% of the forest elephants in the Congo Basin, is facing growing tensions despite the mitigation policies put in place (electric fences, compensation, national strategy). The project takes a multidisciplinary approach combining ecology and social sciences to analyze elephant movements, their diet, and the tolerance of local communities. Three specific objectives guide the study: quantifying the presence of elephants and available food resources, mapping social tolerance by region and period, and evaluating the effectiveness of mitigation measures. The methodology includes acoustic monitoring, drone flights, genetic analysis of feces, and sociological surveys. Conducted over three years, the project aims to produce standardized monitoring tools to support participatory conservation policies. It will contribute to a better understanding of human-elephant conflicts in Gabon and to the identification of levers for sustainable coexistence between wildlife and human populations.
Grace Martine BOBANGUI
Spatial and temporal variation in soil and peatland respiration, stock dynamics, and sequestration strategies
PhD dates : January 2026 - December 2028 Supervisors : Dr. IFO Suspense Averti and Dr. NOUVELLON Yann
Host institutions : Ecole Normale Supérieure (ENS) attached to Université Marien Ngouabi (UMNG) and Joint Research Unit Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes (UMR Eco&Sols) under te supervision of Centre de coopération internationale en recherche agronomique pour le développement (CIRAD)
The aim of this project is to characterize the carbon functioning of two peatland ecosystems in the central basin of the Congo Basin: forest peatlands dominated by palm trees and deciduous trees located in the basin department near Owando. The carbon richness of the soil in these peatlands results from the gradual accumulation of organic matter that decomposes slowly due to anaerobic conditions caused by high groundwater levels. Our study will aim to quantify, in these two types of peatlands, the inputs of organic matter to the soil from litter, their decomposition dynamics, and CO2 emissions from soil respiration as a function of variations in the water table.
Elie Chrisnel NZIGOU DOUBINDOU
The underside of tropical forests, the unexplored biodiversity of the undergrowth
PhD dates: February 2026 - January 2028 Supervisors : Pr. ENGONE OBIANG Nestor, Dr. MBOMA Raymonde, Dr. YOMBIYENI Prudence, Dr. BRETAGNOLLE François, Dr. BARTHELEMY Daniel and Pr. FAYOLLE Adeline Host institution : Université des Sciences et Techniques de Masuku (USTM)
Partners instiutions : Institut de recherche en Ecologie Tropicale (IRET) attached to Centre national de la recherche scientifique et technologique (CENAREST), Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) and Université Bourgogne Europe (UBE)
The establishment of inventory plots has grown rapidly in recent years in the tropics, particularly for estimating carbon stocks in tropical forests and, to a lesser extent, tree diversity. A major effort has been made to standardize inventory protocols, and the ForestPlot.NET standard has become established, with trees measuring more than 10 cm in diameter at breast height being measured in scattered 1-hectare plots. While the inventory of trees over 10 cm in diameter provides a good estimate of biomass and carbon stocks, plant diversity is poorly understood with this type of inventory. The aim of this project is to supplement the information contained in forest inventory plots with an inventory of the undergrowth, assessing its contribution to plant diversity and forest dynamics, particularly through the regeneration of young trees, in different contexts (gradient of pressure on wildlife, logging). The undergrowth inventory will be carried out using a traditional botanical approach combining field identification and the creation of herbariums. Photographs will also be taken to train the artificial intelligence models used by the Pl@ntNet app and facilitate future inventories. The expected results of the project are as follows: an inventory protocol adapted for the understory, a checklist of plants and trees at the Ipassa research station, and the response of the density, composition, and diversity of the understory to wildlife pressure (link to the DefaunC project) and logging (link to the P3FAC and CBSI projects). The role of understory plants (young trees, shrubs, self-supporting vines, and herbaceous plants) in interaction networks (dispersing animals and decomposing fungi) will also be assessed at Ipassa. In addition to providing knowledge about plant biodiversity and biodiversity networks, this project will enable several students (one doctoral student and three master's interns) to be trained in herbarium preparation and botany, develop protocols to complement traditional forest inventories, and strengthen interactions between botanists and ecologists in Gabon.
Ninon BESSON
Foliar demography and phenology of primary and secondary growth in semi-deciduous forests of Cameroon: from leaf bud to stand
PhD dates : January 2025 - December 2027 Supervisors : Dr. HEURET Patrick and Dr. BARBIER Nicolas Host institution : Joint Research Unit botAnique et Modélisation de l'Architecture des Plantes et des végétations (UMR AMAP) under the supervision of Institut de Recherche pour le Développement (IRD) and Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE) Partners institutions : École Normale Supérieure de Yaoundé (ENS) attached to Université de Yaoundé I (UY1) and École Nationale des Eaux et Forêts de Mbalmayo (ENEF)
Tropical rainforests play a major role in CO₂ assimilation and carbon storage. However, despite their importance, the seasonal cycles that govern leaf demography and the factors explaining their interannual and interspecific variability remain largely unknown. These uncertainties limit the ability to reliably model the functioning and properties of these ecosystems. Several areas of research are essential to better understand the temporal and structural variations of these forests. On the one hand, phenology, understood as the study of the temporal organization of recurring biological events in relation to biotic and abiotic factors, is crucial for analyzing the rhythms of leaf emission and senescence. On the other hand, dendrochronology allows us to retrospectively explore the secondary growth cycles of trees based on tree rings. Finally, the study of plant morphology makes it possible to track the alternating phases of primary growth cessation and resumption by identifying markers present on the branches. This thesis aims to explore the dynamics of primary and secondary growth from a temporal perspective, through phenological observations carried out by drone on OFVI super-sites (mainly in Cameroon), and from a structural perspective, by comparing the temporality of senescence and leaf renewal with the resulting morphological and anatomical markers. Such an integrated approach will provide a better understanding of the mechanisms underlying seasonal variations in the productivity of Central African forests.
Diel Jofrés MIHINDOU
Transfers of carbon and bioactive elements in the black waters of the Ivindo basin in Gabon: influence of lotic and lentic environments
PhD dates : March 2026 - February 2029 Supervisors : Pr. MAKAYA MVOUBOU Mike Castane, Dr. POKROVSKY Oleg S. and Dr. BRAUN Jean-Jacques Host institution : Université des Sciences et Techniques de Masuku (USTM)
Parterns institutions : Centre national de la recherche scientifique et technologique (CENAREST), Laboratoire Géosciences Environnement Toulouse (GET) under the supervision of Institut de Recherche pour le Développement (IRD) and Centre National de la Recherche Scientifique (CNRS)
Tropical hydrosystems, particularly the black waters of Central African forests, play an essential role in the global carbon cycle. These environments, rich in dissolved organic matter (DOM) and humic compounds, are major areas of transfer and transformation of bioactive elements (carbon, nutrients, trace metals). However, the mechanisms controlling these flows, particularly between lotic (rivers) and lentic (stagnant areas) environments, remain poorly understood. This thesis focuses on the transfer of carbon and bioactive elements in the black waters of the Ivindo Basin, an emblematic tropical forest ecosystem in Gabon. It aims to characterize the chemical and isotopic composition of MOD, often associated with organic and inorganic colloids (Fe³⁺, Al³⁺), in order to assess their role in the transport of dissolved elements and in the production of greenhouse gases (CO₂, CH₄). The work will be based on field campaigns and physicochemical and geochemical analyses conducted in collaboration between USTM and the GET laboratory (CNRS/IRD). By combining an integrated biogeochemical approach with spatio-temporal monitoring of black waters, this research will provide a better understanding of the contribution of tropical hydrosystems to lateral carbon fluxes and their role in global climate dynamics.
Victoria Hippolyte IYABO
Interrelationships between duraminization and juvenile-adult transition in tropical tree species in relation to intra-tree variability in usage properties
PhD dates : February 2026 - January 2029 Supervisors : Dr. TCHIAMA Rodrigue Safou, Dr. YOMBIYENI Prudence, Dr. EKOMY ANGO Serge, Dr. MOUTOU PITTI Rostand, Dr. THEVENON Marie-France, Dr. BRANCHERIAU Loïc and Dr. GERARD Jean Host institutions : Université des Sciences et Techniques de Masuku (USTM)
Partners institutions : Institut de recherche en Ecologie Tropicale (IRET) attached to the Centre national de la recherche scientifique et technologique (CENAREST), Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) and Université Clermont-Auvergne (UCA)
Logging in Gabon and Central Africa relies on too few so-called “main” species, which undermines the sustainability of forests. To make forest management more balanced, it is necessary to develop the use and value of a greater number of secondary species (LKTS). To this end, the project aims to improve knowledge of the technological characteristics of these underutilized woods and to understand how these properties vary according to their geographical origin and growing conditions. The study focuses mainly on two types of wood stability that are essential for outdoor use: 1) Physical stability: drying shrinkage, anisotropy, density; 2) Biological stability: resistance to wood-decay fungi and termites.The natural durability of wood depends in particular on its chemical composition (secondary metabolites), density, and porosity. However, for most species, there is little data on the variability of these properties according to provenance. Two commercial species in Gabon, Azobé and Niové, have a particular type of wood called intermediate wood (between sapwood and heartwood), whose formation and durability are still poorly understood and appear to vary depending on the region.
Fréjusse Fourier MIASSOUKA MILANDOU
Long-term ecology of the Mayombe forests, influence of climate change and human activities
PhD dates : January 2026 - December 2028 Supervisors : Dr. KOBAWILA Nehl Dorland and Dr. MONTADE Vincent Host institutions : Faculté des Sciences et Techniques (FST) attached to Université Marien Ngouabi (UMNG) and Institut des Sciences de l'Évolution de Montpellier (ISEM) under the supervision of Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS) and Université de Montpellier (U.Montpellier) The project focuses on studying the history of the forests and savannas of southwestern Congo over the last 4,000 years. This thesis aims to understand how these tropical ecosystems, which are of major ecological importance, have responded to climate change (variations in precipitation, fires) and human activities (agriculture, land use). The approach is based on the analysis of lacustrine sedimentary sequences using paleoecological proxies (fossil pollen grains, sedimentary charcoal, sedimentological analyses), combined with climatic and archaeological data from the RainForStory research project (https://anr.fr/ Project-ANR-23-CE27-0023). The results of this thesis will provide a better understanding of the mechanisms responsible for forest-savanna transitions and assess the resilience of the Mayombe Massif and Niari savannas to past disturbances. The expected results will help inform conservation and sustainable management strategies for these ecosystems, while highlighting knowledge about ancient dynamics, whether natural or influenced by local populations.
Samuel Anthony KAYES
Raised fields as markers of past anthropological impacts on peatlands in the central Congo Basin
PhD dates : January 2026 - December 2028 Supervisors : Dr. BOCKO Yannick and Dr. GARCIN Yannick
Host institutions : Faculté des Sciences et Techniques (FST) attached to Université Marien Ngouabi (UMNG) and Centre de Recherche et d'Enseignement en Géosciences de l'Environnement (CEREGE) under the supervision of Institut de Recherche pour le Développement (IRD)
The thesis will study raised fields, anthropogenic structures found along many rivers draining the peatlands of the central Congo Basin. These abundant structures, most of which are now abandoned, bear witness to a flourishing agricultural activity in the past. This multidisciplinary project will define: 1) A detailed typology of abandoned raised fields in Likouala-Mossaka, including information on their shape, size, and, if possible, their function. 2) A detailed radiocarbon chronology of the construction of raised fields will be established. 3) Precise mapping of the total extent of raised fields in the Likouala-Mossaka region will be carried out. 4) A description of the floristic composition of the vegetation growing on and around the raised fields will also be included. This valuable data will provide information on the lasting effects of ancient agriculture on raised fields on the structure and composition of the current vegetation. 5) A comparison between the history of these raised fields and paleoclimatic records and evidence of human occupation/activities in Central Africa will enable an assessment of the factors responsible for their construction and abandonment. 6) An estimate of the carbon stocks of the anthrosols of the raised fields of Likouala-Mossaka will be established. The project will contribute to improving our understanding of climate-human-environment interactions and their effects on the carbon cycle in Central Africa. One of the key ideas underlying this project is that past anthropogenic impacts on environments in Central Africa have been greatly underestimated.
Emmafie Jinelle BONDA
Integrated analysis of the genetic, morphological, and ethnobotanical diversity of oil palm (Elaeis guineensis): comparison between wild and cultivated forms in the Republic of Congo
PhD dates : January 2026 - December 2028 Supervisors : Dr. BOUKA DIPELET Ulrich Gaël and Dr. DUMINIL Jérôme
Host institutions : Université Marien Ngouabi (UMNG) and Joint Research Unit Diversité, Adaptation, Développement des Plantes (UMR DIADE) under the supervisions of Institut de Recherche pour le Développement (IRD), Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) and Université de Montpellier (U.Montpellier) The forests of the Congo Basin provide many goods and services to local populations. They provide food resources, which despite their socio-economic importance, remain poorly studied. This is particularly true of wild oil palms (Elaeis guineensis) and those cultivated by small farmers in fields and home gardens. Uses and management practices will be identified according to major agro-ecological zones (forests, savannas) and the main ethnic groups present in Congo. The morphology of palm nuts will be characterized across the entire territory in order to test the differences between traditional varieties and assess whether there is a domestication syndrome between wild and cultivated forms. The distribution of genetic diversity will be mapped, highlighting areas of high diversity and/or areas of endemism that should be the focus of priority conservation and sustainable management plans. This project will contribute to the promotion of local knowledge, the preservation of oil palm genetic diversity, and the development of appropriate strategies for sustainable exploitation. It could serve as a basis for natural resource management policies and for reforestation and agroforestry projects involving Elaeis guineensis. In addition, it will shed light on the historical processes that have shaped agricultural systems in the forests of the Congo Basin, thereby strengthening our understanding of the interactions between human societies and biodiversity, particularly through the study of oil palm domestication mechanisms.
OFVi doctoral student cohort
Camille Lacroux
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Transcript
LIDAR remote sensing
Above-groundbiomass
Space remote sensing
Flux measurement
Biodiversity
Victoria Hippolyte IYABO
Elie Chrisnel NZIGOU DOUBINDOU
Carmel MOUNZIEGOU-MOUNZIEGOU
Yann IBINGA-BOUASSA
Ninon BESSON
Thomas BOUDRAS
Abel Bridet MOUYABI NTOYO
Maurice BAKALA NKAYA
Samuel Anthony KAYES
Emmafie Jinelle BONDA
Grace Martine BOBANGUI
Frejusse Fourier MIASSOUKA MILANDOU
Diel Jofrés MIHINDOU
Claude Evny MAGANGA MOUSSADJI
Wetlands
Human and social sciences
France PhD
Gabon PhD
Congo PhD
Yann IBINGA-BOUASSA
Estimation and spatialization of carbon stock dynamics and sequestration strategies in Gabon
PhD dates : March 2026 - February 2029 Supervisors : Pr. MEDZA MVE Samson Daudet and Dr. CIAIS Philippe Host institution : Université des Sciences et Techniques de Masuku (USTM) Partners institutions : Agence Gabonaise d'Etudes et d'Observations Spatiales (AGEOS) and Laboratoire des Sciences du Climat et de l'Environnement (LSCE) under the supervision of Commissariat à l'Energie Atomique (CEA)
Gabon's forests cover more than 85% of the country. They are among the world's largest reserves of carbon and biodiversity. Their preservation depends on a thorough understanding of their ecological functioning and continuous monitoring of biodiversity and carbon stocks. To analyze forest dynamics and their effects on climate change, it is crucial to obtain accurate estimates of biomass and carbon stocks. These data are essential for guiding public policies aimed at reducing greenhouse gases and supporting international initiatives such as REDD+ (Reducing Emissions from Deforestation and Forest Degradation). The aim of this project is to develop an innovative and replicable methodology based on deep learning, forest inventory data, and multi-source remote sensing (satellites and drones). Traditional approaches to assessing carbon stocks rely on semi-automated analysis of satellite images and data from forest inventory campaigns. These approaches remain time-consuming and limited in their spatial scope. The integration of emerging technologies, particularly artificial intelligence (AI) combined with multi-source data, opens up new possibilities.
Carmel MOUNZIEGOU-MOUNZIEGOU
Regional analysis of vegetation types and forests in Gabon and the Congo Basin through the integration of heterogeneous sources and models
PhD dates : March 2026 - February 2029 Supervisors : Dr. MAMBIMBA Aboubakar, Dr. COUTERON Pierre and Dr. BARBIER Nicolas Host institution : Joint Research Unit for botAnique et Modélisation de l'Architecture des Plantes et des végétations (UMR AMAP) under the supervision of Institut de Recherche pour le Développement (IRD) and Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) Partners institutions : Agence Gabonaise d'Etudes et d'Observations Spatiales (AGEOS) and Institut de recherche en Ecologie Tropicale (IRET) attached to Centre national de la recherche scientifique et technologique (CENAREST)
This thesis project aims to improve detailed mapping of vegetation types, which is essential for studying biodiversity and the carbon cycle, as current maps are inaccurate (10 km resolution) and based on limited and heterogeneous data. To produce more robust maps, it relies on the integration of multiple remote sensing sources (optical, RADAR, LiDAR, drone) combined with field observations, and uses vegetation models and multimodal deep learning approaches, including self-supervised learning, to improve model performance under varied acquisition conditions. The objectives include developing a reliable methodology, building a diverse training dataset, co-constructing a typology validated by experts, producing national and regional reference maps, and validating them with a spatialized estimate of the reliability of the cartographic products.
Maurice BAKALA NKAYA
Macro- and microscopic responses of commercial and secondary forest species in Congo forests to environmental change
PhD dates : January 2026 - December 2028 Supervisors : Dr. MAKOUANZI EKOMONO Chrissy Garel and Pr. CHAIX Gilles Host institution : Institut National de Recherche Forestière (IRF) Partners institutions : Université Marien Ngouabi (UMNG), Joint Research Unit Amélioration génétique et adaptation des plantes méditerranéennes et tropicales (UMR AGAP) under the supervision of Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) This project focuses on understanding, through experimentation, the adaptation strategies of commercial and secondary forest species in Congo in the face of global environmental change. It contributes to a better understanding of the natural regeneration of species of interest. Its goal is to analyze the responses of these species to changes in light intensity and water regime, both at the macroscopic level (initial growth, plant architecture, leaf traits) and the microscopic level (cell structure, hyperspectral imaging). The methodology revolves around collecting seeds from commercial and secondary species in Congolese forests, testing them in nurseries under controlled conditions, and analyzing the data on two scales: macro and microscopic. An analysis of the trade-offs between characteristics depending on environmental conditions will provide insight into the adaptation strategies developed by species in terms of architecture, anatomy (tissue structure), biochemistry, etc. The expected results aim to provide an understanding of the mechanisms by which commercial and secondary forest species in Congo adapt to environmental change. They will inform conservation and sustainable forest management policies by identifying the most vulnerable species. This project will contribute to a better understanding and preservation of Congolese forest biodiversity and the sustainability of the ecosystem services it provides.
Thomas BOUDRAS
Self-supervised deep learning approaches for high-resolution reconstruction of biomass carbon storage variations in African equatorial forests
PhD dates : December 2025 - November 2028 Supervisors : Dr. CIAIS Philippe, Dr FAYAD Ibrahim and Dr. WIGNERON Jean-Pierre Host institution : Laboratoire des Sciences du Climat et de l'Environnement (LSCE) under the supervision of Université Versailles-Saint-Quentin-en-Yvelines (UVSQ) Partners institutions : Joint Research Unit Interactions Sol Plante Atmosphère (UMR ISPA) under the supervision of Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE)
Equatorial tropical forests play a major role in the global carbon cycle and the preservation of biodiversity, but remain highly susceptible to anthropogenic (fires, degradation, deforestation) and climatic disturbances. The main objective of this thesis is to develop a self-supervised learning (SSL) model capable of processing time series of satellite images to detect and quantify forest changes and biomass variations in African equatorial forests. To do this, we will integrate:
- Multi-temporal Sentinel images.
- High-resolution biomass maps from the OFVi initiative.
- Archives of forest disturbances derived from Landsat series.
- Future data from NISAR and Biomass satellites, subject to availability.
The SSL model will be trained without explicit labels in order to automatically learn robust spatial and temporal representations of forest dynamics. These results will be validated using national inventories and reference data before generating annual carbon balance maps. The proposed methodology thus combines advances in deep learning, remote sensing, and carbon accounting.Abel Bridet MOUYABI NTOYO
Understanding carbon dynamics in Loundoungou (northern Congo) by integrating drone and field data
PhD dates : January 2026 - December 2028 Supervisors : Dr. BOCKO Yannick and Dr. GARCIN Yannick Host institution : Faculté des Sciences et Techniques (FST) attached to Université Marien Ngouabi (UMNG) and Joint Research Unit botAnique et Modélisation de l'Architecture des Plantes et des végétations (UMR AMAP) under the supervison of Institut de Recherche pour le Développement (IRD) Partners institutions : Congolaise Industrielle des Bois (CIB-OLAM)
This thesis project aims to improve our understanding of carbon dynamics in the tropical forests of Central Africa, a crucial issue for anticipating ecosystem responses to global change. Despite their major role in the carbon cycle, current estimates of carbon stocks and fluxes remain highly uncertain, particularly due to the difficulty of measuring tree productivity and mortality on a large scale. The study site, the Loundoungou Observatory (northern Republic of Congo), is a unique “super-site” combining intensive forest inventories with regular acquisitions by drones and LiDAR. The project adopts a multi-scale approach integrating field data, functional trait measurements, monitoring of non-arboreal life forms (lianas, giant herbaceous plants), and high-resolution aerial imagery to understand forest carbon dynamics at this site. This thesis project is structured around three main areas: (1) predicting tree productivity based on available light, functional traits, and biotic interactions; (2) detecting early signs of mortality and quantifying the impact of disturbances, including rare ones, on carbon stocks at the landscape scale; (3) assessing the role of understory vegetation and regeneration in forest dynamics according to biotic and abiotic contexts. This work will yield important findings on the biotic and abiotic determinants of carbon dynamics in dense African forests, with direct implications for vegetation modeling and climate policies such as REDD+. It will also strengthen local capacities in forest ecology and remote sensing through a close partnership between Marien Ngouabi University, IRD, and the forestry company CIB-OLAM.
Claude Evny MAGANGA MOUSSADJI
Coexistence between forest elephants and local communities in Gabon: the role of ecological factors and tolerance in conflict dynamics and mitigation
PhD dates : February 2026 - January 2029 Superviros : Pr. WALI WALI Christian, Pr. NTIE Stephan, Dr. BOURGEOIS Stéphanie, Pr. ROBERT Alexandre and Dr. SIGAUD Marie Host institution : Agence Nationale des Parcs Nationaux (ANPN) Partners institutions : Université Omar Bongo (UOB) and Centre d'écologie et des sciences de la conservation (CESCO) under the supervision of Muséum National d'Histoire Naturelle (MNHN)
This thesis project explores the coexistence between forest elephants (Loxodonta cyclotis) and local communities in Gabon. Faced with an upsurge in human-wildlife conflicts, particularly related to agricultural damage and human losses caused by elephants, this research aims to understand the ecological and social factors that influence these dynamics. Gabon, home to more than 70% of the forest elephants in the Congo Basin, is facing growing tensions despite the mitigation policies put in place (electric fences, compensation, national strategy). The project takes a multidisciplinary approach combining ecology and social sciences to analyze elephant movements, their diet, and the tolerance of local communities. Three specific objectives guide the study: quantifying the presence of elephants and available food resources, mapping social tolerance by region and period, and evaluating the effectiveness of mitigation measures. The methodology includes acoustic monitoring, drone flights, genetic analysis of feces, and sociological surveys. Conducted over three years, the project aims to produce standardized monitoring tools to support participatory conservation policies. It will contribute to a better understanding of human-elephant conflicts in Gabon and to the identification of levers for sustainable coexistence between wildlife and human populations.
Grace Martine BOBANGUI
Spatial and temporal variation in soil and peatland respiration, stock dynamics, and sequestration strategies
PhD dates : January 2026 - December 2028 Supervisors : Dr. IFO Suspense Averti and Dr. NOUVELLON Yann Host institutions : Ecole Normale Supérieure (ENS) attached to Université Marien Ngouabi (UMNG) and Joint Research Unit Ecologie fonctionnelle et biogéochimie des sols et des agro-écosystèmes (UMR Eco&Sols) under te supervision of Centre de coopération internationale en recherche agronomique pour le développement (CIRAD)
The aim of this project is to characterize the carbon functioning of two peatland ecosystems in the central basin of the Congo Basin: forest peatlands dominated by palm trees and deciduous trees located in the basin department near Owando. The carbon richness of the soil in these peatlands results from the gradual accumulation of organic matter that decomposes slowly due to anaerobic conditions caused by high groundwater levels. Our study will aim to quantify, in these two types of peatlands, the inputs of organic matter to the soil from litter, their decomposition dynamics, and CO2 emissions from soil respiration as a function of variations in the water table.
Elie Chrisnel NZIGOU DOUBINDOU
The underside of tropical forests, the unexplored biodiversity of the undergrowth
PhD dates: February 2026 - January 2028 Supervisors : Pr. ENGONE OBIANG Nestor, Dr. MBOMA Raymonde, Dr. YOMBIYENI Prudence, Dr. BRETAGNOLLE François, Dr. BARTHELEMY Daniel and Pr. FAYOLLE Adeline Host institution : Université des Sciences et Techniques de Masuku (USTM) Partners instiutions : Institut de recherche en Ecologie Tropicale (IRET) attached to Centre national de la recherche scientifique et technologique (CENAREST), Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) and Université Bourgogne Europe (UBE)
The establishment of inventory plots has grown rapidly in recent years in the tropics, particularly for estimating carbon stocks in tropical forests and, to a lesser extent, tree diversity. A major effort has been made to standardize inventory protocols, and the ForestPlot.NET standard has become established, with trees measuring more than 10 cm in diameter at breast height being measured in scattered 1-hectare plots. While the inventory of trees over 10 cm in diameter provides a good estimate of biomass and carbon stocks, plant diversity is poorly understood with this type of inventory. The aim of this project is to supplement the information contained in forest inventory plots with an inventory of the undergrowth, assessing its contribution to plant diversity and forest dynamics, particularly through the regeneration of young trees, in different contexts (gradient of pressure on wildlife, logging). The undergrowth inventory will be carried out using a traditional botanical approach combining field identification and the creation of herbariums. Photographs will also be taken to train the artificial intelligence models used by the Pl@ntNet app and facilitate future inventories. The expected results of the project are as follows: an inventory protocol adapted for the understory, a checklist of plants and trees at the Ipassa research station, and the response of the density, composition, and diversity of the understory to wildlife pressure (link to the DefaunC project) and logging (link to the P3FAC and CBSI projects). The role of understory plants (young trees, shrubs, self-supporting vines, and herbaceous plants) in interaction networks (dispersing animals and decomposing fungi) will also be assessed at Ipassa. In addition to providing knowledge about plant biodiversity and biodiversity networks, this project will enable several students (one doctoral student and three master's interns) to be trained in herbarium preparation and botany, develop protocols to complement traditional forest inventories, and strengthen interactions between botanists and ecologists in Gabon.
Ninon BESSON
Foliar demography and phenology of primary and secondary growth in semi-deciduous forests of Cameroon: from leaf bud to stand
PhD dates : January 2025 - December 2027 Supervisors : Dr. HEURET Patrick and Dr. BARBIER Nicolas Host institution : Joint Research Unit botAnique et Modélisation de l'Architecture des Plantes et des végétations (UMR AMAP) under the supervision of Institut de Recherche pour le Développement (IRD) and Institut national de recherche pour l'agriculture, l'alimentation et l'environnement (INRAE) Partners institutions : École Normale Supérieure de Yaoundé (ENS) attached to Université de Yaoundé I (UY1) and École Nationale des Eaux et Forêts de Mbalmayo (ENEF)
Tropical rainforests play a major role in CO₂ assimilation and carbon storage. However, despite their importance, the seasonal cycles that govern leaf demography and the factors explaining their interannual and interspecific variability remain largely unknown. These uncertainties limit the ability to reliably model the functioning and properties of these ecosystems. Several areas of research are essential to better understand the temporal and structural variations of these forests. On the one hand, phenology, understood as the study of the temporal organization of recurring biological events in relation to biotic and abiotic factors, is crucial for analyzing the rhythms of leaf emission and senescence. On the other hand, dendrochronology allows us to retrospectively explore the secondary growth cycles of trees based on tree rings. Finally, the study of plant morphology makes it possible to track the alternating phases of primary growth cessation and resumption by identifying markers present on the branches. This thesis aims to explore the dynamics of primary and secondary growth from a temporal perspective, through phenological observations carried out by drone on OFVI super-sites (mainly in Cameroon), and from a structural perspective, by comparing the temporality of senescence and leaf renewal with the resulting morphological and anatomical markers. Such an integrated approach will provide a better understanding of the mechanisms underlying seasonal variations in the productivity of Central African forests.
Diel Jofrés MIHINDOU
Transfers of carbon and bioactive elements in the black waters of the Ivindo basin in Gabon: influence of lotic and lentic environments
PhD dates : March 2026 - February 2029 Supervisors : Pr. MAKAYA MVOUBOU Mike Castane, Dr. POKROVSKY Oleg S. and Dr. BRAUN Jean-Jacques Host institution : Université des Sciences et Techniques de Masuku (USTM) Parterns institutions : Centre national de la recherche scientifique et technologique (CENAREST), Laboratoire Géosciences Environnement Toulouse (GET) under the supervision of Institut de Recherche pour le Développement (IRD) and Centre National de la Recherche Scientifique (CNRS)
Tropical hydrosystems, particularly the black waters of Central African forests, play an essential role in the global carbon cycle. These environments, rich in dissolved organic matter (DOM) and humic compounds, are major areas of transfer and transformation of bioactive elements (carbon, nutrients, trace metals). However, the mechanisms controlling these flows, particularly between lotic (rivers) and lentic (stagnant areas) environments, remain poorly understood. This thesis focuses on the transfer of carbon and bioactive elements in the black waters of the Ivindo Basin, an emblematic tropical forest ecosystem in Gabon. It aims to characterize the chemical and isotopic composition of MOD, often associated with organic and inorganic colloids (Fe³⁺, Al³⁺), in order to assess their role in the transport of dissolved elements and in the production of greenhouse gases (CO₂, CH₄). The work will be based on field campaigns and physicochemical and geochemical analyses conducted in collaboration between USTM and the GET laboratory (CNRS/IRD). By combining an integrated biogeochemical approach with spatio-temporal monitoring of black waters, this research will provide a better understanding of the contribution of tropical hydrosystems to lateral carbon fluxes and their role in global climate dynamics.
Victoria Hippolyte IYABO
Interrelationships between duraminization and juvenile-adult transition in tropical tree species in relation to intra-tree variability in usage properties
PhD dates : February 2026 - January 2029 Supervisors : Dr. TCHIAMA Rodrigue Safou, Dr. YOMBIYENI Prudence, Dr. EKOMY ANGO Serge, Dr. MOUTOU PITTI Rostand, Dr. THEVENON Marie-France, Dr. BRANCHERIAU Loïc and Dr. GERARD Jean Host institutions : Université des Sciences et Techniques de Masuku (USTM) Partners institutions : Institut de recherche en Ecologie Tropicale (IRET) attached to the Centre national de la recherche scientifique et technologique (CENAREST), Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) and Université Clermont-Auvergne (UCA)
Logging in Gabon and Central Africa relies on too few so-called “main” species, which undermines the sustainability of forests. To make forest management more balanced, it is necessary to develop the use and value of a greater number of secondary species (LKTS). To this end, the project aims to improve knowledge of the technological characteristics of these underutilized woods and to understand how these properties vary according to their geographical origin and growing conditions. The study focuses mainly on two types of wood stability that are essential for outdoor use: 1) Physical stability: drying shrinkage, anisotropy, density; 2) Biological stability: resistance to wood-decay fungi and termites.The natural durability of wood depends in particular on its chemical composition (secondary metabolites), density, and porosity. However, for most species, there is little data on the variability of these properties according to provenance. Two commercial species in Gabon, Azobé and Niové, have a particular type of wood called intermediate wood (between sapwood and heartwood), whose formation and durability are still poorly understood and appear to vary depending on the region.
Fréjusse Fourier MIASSOUKA MILANDOU
Long-term ecology of the Mayombe forests, influence of climate change and human activities
PhD dates : January 2026 - December 2028 Supervisors : Dr. KOBAWILA Nehl Dorland and Dr. MONTADE Vincent Host institutions : Faculté des Sciences et Techniques (FST) attached to Université Marien Ngouabi (UMNG) and Institut des Sciences de l'Évolution de Montpellier (ISEM) under the supervision of Institut de Recherche pour le Développement (IRD), Centre National de la Recherche Scientifique (CNRS) and Université de Montpellier (U.Montpellier) The project focuses on studying the history of the forests and savannas of southwestern Congo over the last 4,000 years. This thesis aims to understand how these tropical ecosystems, which are of major ecological importance, have responded to climate change (variations in precipitation, fires) and human activities (agriculture, land use). The approach is based on the analysis of lacustrine sedimentary sequences using paleoecological proxies (fossil pollen grains, sedimentary charcoal, sedimentological analyses), combined with climatic and archaeological data from the RainForStory research project (https://anr.fr/ Project-ANR-23-CE27-0023). The results of this thesis will provide a better understanding of the mechanisms responsible for forest-savanna transitions and assess the resilience of the Mayombe Massif and Niari savannas to past disturbances. The expected results will help inform conservation and sustainable management strategies for these ecosystems, while highlighting knowledge about ancient dynamics, whether natural or influenced by local populations.
Samuel Anthony KAYES
Raised fields as markers of past anthropological impacts on peatlands in the central Congo Basin
PhD dates : January 2026 - December 2028 Supervisors : Dr. BOCKO Yannick and Dr. GARCIN Yannick Host institutions : Faculté des Sciences et Techniques (FST) attached to Université Marien Ngouabi (UMNG) and Centre de Recherche et d'Enseignement en Géosciences de l'Environnement (CEREGE) under the supervision of Institut de Recherche pour le Développement (IRD)
The thesis will study raised fields, anthropogenic structures found along many rivers draining the peatlands of the central Congo Basin. These abundant structures, most of which are now abandoned, bear witness to a flourishing agricultural activity in the past. This multidisciplinary project will define: 1) A detailed typology of abandoned raised fields in Likouala-Mossaka, including information on their shape, size, and, if possible, their function. 2) A detailed radiocarbon chronology of the construction of raised fields will be established. 3) Precise mapping of the total extent of raised fields in the Likouala-Mossaka region will be carried out. 4) A description of the floristic composition of the vegetation growing on and around the raised fields will also be included. This valuable data will provide information on the lasting effects of ancient agriculture on raised fields on the structure and composition of the current vegetation. 5) A comparison between the history of these raised fields and paleoclimatic records and evidence of human occupation/activities in Central Africa will enable an assessment of the factors responsible for their construction and abandonment. 6) An estimate of the carbon stocks of the anthrosols of the raised fields of Likouala-Mossaka will be established. The project will contribute to improving our understanding of climate-human-environment interactions and their effects on the carbon cycle in Central Africa. One of the key ideas underlying this project is that past anthropogenic impacts on environments in Central Africa have been greatly underestimated.
Emmafie Jinelle BONDA
Integrated analysis of the genetic, morphological, and ethnobotanical diversity of oil palm (Elaeis guineensis): comparison between wild and cultivated forms in the Republic of Congo
PhD dates : January 2026 - December 2028 Supervisors : Dr. BOUKA DIPELET Ulrich Gaël and Dr. DUMINIL Jérôme Host institutions : Université Marien Ngouabi (UMNG) and Joint Research Unit Diversité, Adaptation, Développement des Plantes (UMR DIADE) under the supervisions of Institut de Recherche pour le Développement (IRD), Centre de coopération internationale en recherche agronomique pour le développement (CIRAD) and Université de Montpellier (U.Montpellier) The forests of the Congo Basin provide many goods and services to local populations. They provide food resources, which despite their socio-economic importance, remain poorly studied. This is particularly true of wild oil palms (Elaeis guineensis) and those cultivated by small farmers in fields and home gardens. Uses and management practices will be identified according to major agro-ecological zones (forests, savannas) and the main ethnic groups present in Congo. The morphology of palm nuts will be characterized across the entire territory in order to test the differences between traditional varieties and assess whether there is a domestication syndrome between wild and cultivated forms. The distribution of genetic diversity will be mapped, highlighting areas of high diversity and/or areas of endemism that should be the focus of priority conservation and sustainable management plans. This project will contribute to the promotion of local knowledge, the preservation of oil palm genetic diversity, and the development of appropriate strategies for sustainable exploitation. It could serve as a basis for natural resource management policies and for reforestation and agroforestry projects involving Elaeis guineensis. In addition, it will shed light on the historical processes that have shaped agricultural systems in the forests of the Congo Basin, thereby strengthening our understanding of the interactions between human societies and biodiversity, particularly through the study of oil palm domestication mechanisms.