Comparative ecology of tropical ecosystems (in Africa)

After a short presentation of my career trajectory in academia, and of the PhD students and post-doctoral fellows I had the chance to supervise, I present a synthesis of the research work I conducted over the last decade on the comparative ecology of tropical ecosystems in Africa. This work is anchored into applied forest sciences and the data that were accumulated to answer practical questions also helped answer more fundamental questions in ecology. In my work, trees are used as the starting point in the understanding of tropical ecosystems, mostly moist forests but also drier formations, such as woodlands and savannas. With a background in community and functional ecology and a position in Gembloux Agro-Bio Tech, University of Liège, targeting tropical tree allometry and forest carbon, I derived two types of comparative approaches in my research activities, I compare either sites (trees or stands) or lineages (species or genera, mostly). For the site comparison, I used either the angle of tree architecture and stand structure or that of diversity and composition, at different spatial and temporal scales, from tree allometry and biomass estimates, up to the landscape scale for the structural approach, and from diversity recovery after logging, the delineation of forest types for management and up to biogeography studies, including cross-taxonomic and cross-continent comparisons for the diversity approach. For the lineage comparison, the concept of functional traits has been central and transversal since it allowed relating the structure and diversity approaches. It was however first adapted to tropical trees for which leaves are difficult to access, and size can vary tremendously over the tree life span and among tree life histories. Allometric or size-controlled traits were notably derived from tree measurements in the field and computed at a certain diameter to compare species of contrasted morphologies. Wood anatomical traits were also investigated and notably related to tree hydraulics. In this line, I finally propose a research project on tree and forest seasonal functioning, and response to drought. Tropical forests of central Africa are indeed found under drier and more seasonal climates than their south-eastern Asian and south American counterparts, and their resilience to climate (change) is a timely topic. These research perspectives will complement ongoing work on (i) the biogeography of Africa using species occurrence derived from herbarium records instead of checklists, (ii) carbon and biodiversity changes over the last decade by re-census a set of existing plots in the Congo basin, and on (iii) the seasonality in tree and forest functioning, using tree dendrometers and phenological cameras (PhenoCams) to monitor in depth how trees cope with the dry season. This project entitled CANOPI has been accepted for founding and offer the opportunity to collect unique ground-based measurements of tree and forest functioning in central Africa.