Fully-funded PhD position: General principles of detritivore faeces production in temperate ecosystems
Link for full description: https://www.dropbox.com/scl/fi/fr0289rb3mpw3fdpqzn30/PhD-position.pdf?rlkey=al55wqpzp4mc2b7j9n16o28e1&st=efdqpswf&dl=0
The project
The transformation of plant litter into faeces by detritivorous soil animals is a major pathway of organic matter processing in soils. However, the magnitude of this flux, the factors controlling it, and the fate of detritivore faeces in soils remain poorly understood. As a result, detritivory is still largely overlooked in current representations of soil functioning and biogeochemical models.
This PhD project will investigate the drivers of faeces production across diverse detritivorous soil animals (Fig. 1). It will evaluate how this process varies across taxa and environmental contexts, and how the physico-chemical characteristics of faeces influence their microbial use, decomposition and greenhouse gases emissions.
The PhD project will be part of a broader national research group on forests and agroforests ecosystems, within the PEPR SolsVivants, which aims to better understand soil interaction networks and their role in soil multifunctionality. The PhD project will be at the centre of a series of tasks on detritivory that will be supported by five master students on specific aspects in diverse research centres across France.
The applicant will contribute to field sampling to collect detritivores, faeces, litter and soils across a network of temperate forests and agroforests in France, and to lab analyses using a range of approaches to address key questions: What do detritivores feed on? What controls faeces production? Which factors determine faeces quality? And how does faeces quality affect its fate in soil?
Methods will include field measurements of faeces production, functional traits and metabolism of soil animals, characterisation of litter and faeces chemistry, microbial and molecular analyses, and decomposition experiments. The wider project includes links with trophic-network and biogeochemical modelling, to which the candidate may contribute, depending on their profile and interests. This PhD will provide new insights into a major but neglected pathway of soil organic matter transformation, with implications for both fundamental soil ecology and predictive models of ecosystem functioning.
We are looking for
We welcome applications from candidates with a Master’s degree in ecology, biogeochemistry, environmental science, or related disciplines. We are particularly interested in applicants with experience in: soil ecology, fieldwork, laboratory or controlled-condition experiments, invertebrate identification, biogeochemistry, and/or functional trait approaches.
The candidate should be comfortable with data analysis in R, and interested in working at the interface between functional ecology, biogeochemistry, and biodiversity science. Good organisational skills, scientific curiosity, and the ability to work both independently and collaboratively will be important. Proficiency in written and spoken English is required.
We offer
The successful applicant will join the research unit Eco&Sols in Montpellier, France, and be enrolled at the Institut Agro Montpellier, will be part of the Gaia Doctoral School, and employed by INRAE with a gross monthly salary of 2300€, for 36 months, starting October 1st 2026. Eco&Sols provides a stimulating research environment and access to the technical facilities required for the project. The candidate will have access to a subsidised canteen, 6-weeks paid leave per year, and opportunities to attend specific training programmes and courses as part of the doctoral studies.
The applicant will be supervised by François-Xavier Joly at Eco&Sols, where most of the work will take place, and co-supervised by Benjamin Pey at the CRBE research unit (Toulouse) where some elemental and molecular analyses will be carried out. Beyond the supervisory team, the project will involve close interactions with a national network of collaborators and may include opportunities for exchanges with partner laboratories in France and abroad. The successful applicant will also have the possibility to develop their own ideas with side-projects, within the general context of the PhD.
To apply
Please send a CV, cover letter (in English or French) describing your interest and experience, available university grades, and contact details of two referees who could provide a reference letter, to François-Xavier Joly (francois-xavier.joly@inrae.fr) and Benjamin Pey (benjamin.pey@toulouse-inp.fr).
We will start reviewing applications at the end of April and will keep the position open until filled. We thus encourage you to apply as soon as possible. Before applying, feel free to get in touch for an informal discussion to know more about the project and other aspects of the PhD.
Further reading
Joly et al. 2020 Communications Biology | Coq et al. 2022 Geoderma | Joly et al. 2023 Oikos | Marchand et al. 2024 Functional Ecology | Angst et al. 2024 Nature Communications | Zi et al. 2025 Soil Biology and Biochemistry
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