ED Sciences et environnements
Toward a forest bocage: broadleaved hedgerows as a Nature-Based Solution to enhance the resistance of plantation forest landscapes
by Nattan PLAT (BIOGECO - BIOdiversité, Gènes & Communautés)
The defense will take place at 14h00 - Salle des chênaies INRAE BIOGECO 69 route d'Arcachon 33610 Cestas-Pierroton
in front of the jury composed of
- Hervé JACTEL - Directeur de recherche émérite - Université de Bordeaux - Directeur de these
- Andrea BATTISTI - Professeur - University of Padova - Rapporteur
- Annie OUIN - Professeure des universités - ENSAT Toulouse - INRAE Dynafor - Rapporteur
- Audrey ALIGNIER - Chargée de recherche - INRAE BAGAP - Examinateur
- Marc DUFRENE - Professeur - Université de Liège - Examinateur
In the context of global change, forest ecosystems are increasingly exposed to disturbances, particularly insect pest outbreaks. Monospecific plantation forests are particularly vulnerable and also support lower biodiversity compared to semi-natural forests. Forest diversification, whether implemented at the stand or landscape scale, is a promising approach to enhancing their resistance, but this raises management and governance challenges that often slow down or hinder its implementation. In this thesis, we applied the concept of Nature-Based Solutions to explore the potential benefits of establishing a network of broadleaved hedgerows within a pine plantation landscape, referred to as a “forest bocage”. Inspired by the traditional “bocage” (i.e., agricultural landscape with hedgerows), this forest landscape diversification strategy is based on two main hypotheses: (1) hedgerows can host natural enemies that help control pests (i.e., conservation biological control), and (2) they promote biodiversity conservation. These hypotheses were tested in the Landes de Gascogne Forest in southwestern France, a large forested area of over one million hectares, dominated by monospecific stands of maritime pine (Pinus pinaster). Using existing broadleaved hedgerows and remnants (considered as source habitats for forest biodiversity), we assessed their effects on infestation by the pine processionary moth (Thaumetopoea pityocampa) and on the activity of its avian and bat predators. In parallel, we compared multi-taxonomic biodiversity (i.e., understorey vegetation, butterflies, carabids, spiders, birds and reptiles) between broadleaved hedgerows and pine stand borders, and characterized hedgerow structure using an innovative airborne LiDAR approach. Our results show that broadleaved hedgerows reduce pine processionary moth infestations through a barrier effect that limits host tree detection by adult moths. The great tit (Parus major), particularly active in hedgerows during spring, contributes to the winter regulation of processionary caterpillars. Moreover, multi-taxonomic biodiversity was significantly higher in hedgerows than in pine edges, with hedgerows harbouring more forest specialist and rare species. LiDAR data analyses also revealed that hedgerows with dense canopy harbour more forest specialist species, while high structural heterogeneity in canopy and understory promotes a greater multi-taxonomic biodiversity. By demonstrating that broadleaved hedgerows can simultaneously mitigate pest damage and restore biodiversity, this thesis highlights that the “forest bocage” represents a relevant Nature-Based Solution to enhance the resistance of pine plantation landscapes against pest insects. Further research is nonetheless needed to assess their potential role in mitigating abiotic disturbances, particularly storms and wildfires.
ED Sociétés, Politique, Santé Publique
Study of teaching and learning conditions for dividing a rational number by a rational number in secondary school Choosing an entry: the act of measuring by commensuration
by Aurélien OVIDE (Laboratoire d'épistémologie et didactiques disciplinaires, professionnelle et comparée de Bordeaux)
The defense will take place at 14h00 - Amphi B 351 Cours de la Libération Bâtiment A29 33405 Talence
in front of the jury composed of
- Lalina COULANGE - Professeure des universités - UNIVERSITÉ DE BORDEAUX - Directeur de these
- Anne-Cécile MATHÉ - Maîtresse de conférences - UNIVERSITÉ CLERMONT AUVERGNE - Rapporteur
- Christine CHAMBRIS - Professeure des universités - CY CERGY PARIS UNIVERSITÉ - Rapporteur
- Martine JAUBERT - Professeure émérite - UNIVERSITÉ DE BORDEAUX - Examinateur
- Jean-Luc DORIER - Professeur - UNIVERSITÉ DE GENÈVE - Examinateur
- Éric RODITI - Professeur des universités - UNIVERSITÉ PARIS CITÉ - Examinateur
- Jérôme PROULX - Professeur - UNIVERSITÉ DU QUÉBEC À MONTRÉAL - Examinateur
Based on the results of didactic engineering for research on rational numbers, the situation of the thickness of sheets of paper, we explore new directions of research able to produce a process for developing the division of a rational-measure by a rational-measure using commensuration as a defining model of the fraction. Our research is rooted in the study of rational numbers in relation to measurement. This context leads us to explore the potential of the commensuration meaning of the fraction in situations organised around a variety of multiplicative relationships and (relative) units. These possibilities are put into perspective with recommendations documented in educational literature, published by educational institutions and drawn from school textbooks. The theoretical framework of the Theory of Didactic Situations leads us to develop a phenomenotechnical didactic engineering approach based on rational-measurement and multiplicative relationships. A posteriori analyses of materials collected during an experiment with 8th grade students on the engineering process of dividing a rational measure by a rational measure are supported by a second theoretical contribution, the hypothesis of the "scholarly disciplinary discursive community".