In ecology, a community is an assemblage of populations of two or more different species occupying the same geographical area. Community ecology encompasses the study of the interactions between species in communities on many spatial and temporal scales. This includes the distribution, structure, abundance and demography of species interacting in the community. Within our research group, we are mainly focused on forest ecosystems and assemblage of tree species. While increasing scientific knowledge on forest ecosystems, our objective is to improve forest management and enhance forest ecosystem services (wood production, biodiversity, carbon sequestration, etc.).
Competition between species
Species can compete with each other for finite resources (e.g. water, nutrients or sunlight). Competition is considered to be an important mechanism determining population size, biomass and species richness in the community. Through our research, we try to identify the strategy of each species regarding competition for resources in the community basing our studies on species traits, demography and phylogeny. Selected references: 3, 4, 12, 22.
Intraspecific variability is the overall variability of biological characteristics (functional traits, life-history characteristics) expressed by individuals within a species. Observed intraspecific variability has various causes including genetics and phenotypic plasticity. Intraspecific variability has often been left aside in favor of interspecific variability to explain community functioning. In our research group, we work at quantifying intraspecific variability and we study its effect on species competition. Selected references: 3, 5, 8.
A rare species is a group of organisms that are very uncommon or scarce in a community. In tropical forests, where the number of species may be greater than 100 per hectare, many species are rare and represented only by a few individuals. Knowledge about these species is usually scarce. This is problematic as to understand the functioning of the community, we need information on the behavior of each species. In our research team, we develop approaches to make the most of the few observations that is available for rare species. As an alternative to the approach by group of species or the approach by functional traits, we investigate the interest of using hierarchical mixed effect models to characterize rare species. This type of models is a compromise between a theoretical and biologically coherent average model for all species and a species specific model estimated from the few observations for each species. Selected references: twoe, 6, 18.
Conservation biology is the scientific study of the nature and status of Earth’s biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions. Land-use change and climate change are two main threats to biodiversity. Through our research group, we try to provide tools for conservation planning with the aim of reducing tropical deforestation and adapting to climate-change.
Deforestation, carbon emissions, and biodiversity loss
Tropical deforestation is responsible for a major decline in biodiversity, for a considerable proportion (6-17%) of global carbon dioxide emissions that affect climate change and is the first step toward land desertification. Around 13 million hectares of tropical forest are deforested each year around the world. The REDD+ programme (Reducing emissions from deforestation and forest degradation) has emerged as a new potential to curb deforestation in developing countries combining both development and conservation actions. Our research group work at providing accurate estimates of carbon stocks in tropical forests and identifying the social and environmental causes of deforestation to improve conservation planning. Selected references: phcfM, 9, 11, 14.
Species vulnerability to climate change
Biodiversity is affected by current anthropogenic climate change. Although throughout Earth’s history the climate has always changed with ecosystems and species coming and going, current rapid climate change affects ecosystems and species ability to adapt and so biodiversity loss increases. The current extinction rate is now approaching 1,000 times the background rate rivaling the five mass extinctions of past geologic history. Within our research group, we assess the vulnerability of tree species or forest-restricted animal species to climate change. Using species distribution models and projecting species distribution under future climate, our objective is to identify climatic refugea area for biodiversity. Using biodiversity maps, we propose conservation strategies to adapt to climate change, increasing the effectiveness of present protected area networks. Selected references: hSDM, 15, 24.
Statistics applied to ecology
Statistical models can be used to draw inferences about the ecological process or population under study. Inference is a vital element of scientific advance, since it provides a way to draw conclusions from data that are subject to random variation. Models can then be used to forecast ecological processes and provide support to managers for decision making. Within our research group, we work at providing new statistical methods and tools to solve methodological problems associated to the analysis of ecological data-sets, thus offering opportunities to provide new answers to scientific questions in ecology.
To do so, we are particularly focused on the development of hierarchical Bayesian models. We try to make the statistical methods and functions we develop available in R or Python packages. We developed various methods and tools for modelling anthropogenic deforestation (forestatrisk, phcfM), species distribution (jSDM, hSDM), and tropical forest dynamics (twoe). We have also contributed to the development of functions for parameter inference in a hierarchical Bayesian framework that have been included in packages with broad applications (MCMCpack). Selected references: hSDM, twoe, phcfM, 1, 14.
2020 – 2023 METRADICA, Mechanistic traits to predict shifts in tree species abundance and distribution with climate change in the Amazonian forest. Labex CEBA, Projets stratégiques, 200,000 €, 48 months. Partners: UMR AMAP (France), UMR Ecofog (French Guiana), UPR Forêts et Sociétés (France), UMR Silva (France). Coordination: Clément Stahl (INRAE, UMR Ecofog), Ghislain Vieilledent (Cirad, UMR AMAP).
2021 – 2023 INTRACO, Role of intraspecific variability in tree species coexistence in tropical forest. FRB-Cesab (France) – sDiv (Germany), Synergy Call 2019, 4 workshops (∼40,000 €), 24 months. Participants: Ghislain Vieilledent (Cirad, France), Isabelle Maréchaux (INRAE, France), Adam T. Clark (University of Graz, Austria), James S. Clark (Duke University, USA / INRAE, France), Benoît Courbaud (INRAE, France), Camille Girard-Tercieux (CNRS, France), Nadja Rüger (iDiv, Germany), and several invited researchers. Coordination: Ghislain Vieilledent (Cirad, UMR AMAP), Isabelle Maréchaux (INRAE, UMR AMAP).
2014 – 2019 BIOSCENEMADA, Biodiversity scenarios under the effect of climate change and future deforestation in Madagascar. FRB – FFEM, AAP-SCEN-2013-I, 265,000 €, 60 months. Partners: Cirad, UMR AMAP (France), WCS and REBIOMA (Madagascar), ETC Terra (France), Office National pour l’Environnement (Madagascar). Coordination: Ghislain Vieilledent (Cirad, UMR AMAP).
In charge of work-packages
2019 – 2022 RELIQUES, Effect of forest fragmentation on biodiversity in New-Caledonia. CNRT, 251,380 €, 36 months. Partners: Cirad, UMR AMAP (France), IRD, UMR AMAP (France), IRD, UMR IMBE (France). Coordination: Philippe Birnbaum (Cirad, UMR AMAP).
Participation in projects
2023 – 2026 EDENE, Ecological Dynamics behind species Extinctions in Novel Ecosystems. ANR, 302,165 €. Coordination: Robin Pouteau (IRD, UMR AMAP).
2022 – 2025 ALT, Amazonian Landscapes in Transition. ANR, 659,799 €. Coordination: Jérôme Chave (CNRS, Université de Toulouse).
2022 – 2025 GUARDEN, safeGUARDing biodivErsity aNd critical ecosystem services across sectors and scales. Union Européenne, Horizon Europe, 4.5M €. Coordination: Pierre Bonnet (Cirad, UMR AMAP).
2019 – 2023 GAMBAS, Generating Advances in Modeling Biodiversity And ecosystem Services (GAMBAS): statistical improvements and ecological relevance of joint species distribution models. ANR, 569,033 €. Coordination: Frédéric Mortier (Cirad, UPR Forêts et Sociétés).
2022 Developing the riskmapjnr Python package for obtaining map of the deforestation risk following the JNR (Jurisdictional Nested REDD+) methodology, FAO, 28,000 €.
2012 – 2013 Technical assistance to Office National pour l’Environnement for implementing REDD+ in Madagascar. AFD, 290,210 €, 24 months. Partners: Office National pour l’Environnement (Madagascar), Helvetas Swiss Intercooperation (Switzerland), Cirad, UPR Forêts et Sociétés (France). Coordination: Julia Randimbisoa (Helvetas).
2012 Forest inventories and development of height-diameter allometric equations for Madagascar dry forests. WWF, 3500 €.
2011 – 2012 Modelling deforestation (intensity and location of the deforestation) in Madagascar. GoodPlanet, 9000 €.
2010 – 2011 Developing biomass allometric equations for Madagascar forests. WWF – GoodPlanet, 8750 €.