Multitaxonomic and functional integration of soil biota for sustainable silviculture (Project ISYLDUR)

French forests, which cover almost one-third of the country, are undergoing rapid and profound transformations under climate change. Dieback events, regeneration failures, shifts in species suitability and growing demands for adaptation strategies make it urgent to understand how forest ecosystems will sustain ecological services it actually provides in the coming decades. Yet one of the key components of forest functioning - soil biodiversity - remains insufficiently known, despite its central role in nutrient cycling, carbon storage, decomposition processes and ecological resilience.

New management trajectories (e.g. mixed stands, species diversification, modified stand density, innovative regeneration strategies) are being deployed at large scale across France. However, their impacts on the structure and functioning of soil communities (microbial, fungal and faunal) are still poorly assessed.

This PhD thesis is part of the national BOSFOR project (ANR-25-PEFO-0001) / PEPR Forestt which mobilizes a large consortium of soil ecologists, forest ecologists, modellers and stakeholders to characterise and monitor forest soil biodiversity. The candidate will work within a strong collaborative framework. USC INRAE ECODIV – Rouen (soil–plant interactions, soil fauna ecology) and UMR INRAE BIOGECO  - Bordeaux (microbial ecology, tree–microbe interactions), providing complementary expertise.

The project aims to explore how forest management practices shape the organisation and functioning of soil biocenoses across multiple taxonomic groups, using a combination of national long-term experimental sites, molecular tools, community ecology approaches and functional trait analyses. While part of the BOSFOR project, the thesis remains deliberately flexible, offering the candidate the opportunity to refine research questions, choose focal taxa, and develop original methodological or conceptual angles in agreement with the consortium.

This work will contribute to a broader national effort to integrate soil biodiversity into forest monitoring, modelling and decision-making, thus supporting the transition towards resilient and multifunctional forests.

Supervisors: Directors (Pr. Michaël Aubert – USC INRAE 1499 – Ecodiv, Université de Rouen Normandie & Dr. HDR Heidy Schimann – UMR INRAE 1202 BIOGECO, Université de Bordeaux) / Co-Supervisors : Dr. Pierre Ganault - USC INRAE 1499 – Ecodiv, Université de Rouen Normandie.

Location: University of Rouen Normandy (ECODIV – USC INRAE 1499), Regular planned visits to UMR INRAE 1202 BIOGECO, Bordeaux

The research themes of the ECODIV unit focus on the study of biological–functional relationships at the soil–vegetation interface in weakly anthropized terrestrial ecosystems. We investigate both the mechanisms of species assembly (fauna, flora, microorganisms), the dynamics of populations and communities within aboveground and belowground compartments, and the dynamics of organic matter at the scale of this interface.

The approaches developed rely on filter theory, as well as on the mechanisms of interactions and feedbacks among different communities, particularly through a trait-based approach. They also include the study of soil functioning, specifically in terms of organic matter dynamics (litter decomposition), element dynamics (carbon and nitrogen), carbon storage and release, and soil structuring.

This research framework is conducted within the context of global change, including ecological restoration, and along gradients of abiotic constraints.

Required skills

• Master’s degree in ecology, soil science, soil biology , or related fields.
• Interest in field ecology, multi‑taxa approaches and forest ecosystems.
• Valuable skills: R for statistics, community ecology, environmental DNA, ecological modelling.
• Ability to work collaboratively within large research networks (BOSFOR, PEPR FORESTT).
• Strong written and oral communication skills.
• Driving licence