BOSFOR – Biodiversity of forest soils

Coordinating institution : Aix Marseille University
Partner institutions : INRAE | CNRS | IRD | University of Rouen | University of Toulouse | INP Toulouse | École normale supérieure – PSL
Project leader : Mathieu Santonja (Aix Marseille University)
Project duration : 48 months | 1 October 2025 → 30 September 2029

Covering 17 million hectares, French forests account for one third of the country’s territory. They face climate change as well as unsustainable silvicultural practices, particularly as harvesting and reforestation rates continue to rise to meet bioeconomy and renewable energy demands. Management choices, including those aimed at modulating harvest levels, species composition, or reforestation rates, affect stand biodiversity. These decisions also impact soil biodiversity, for which our knowledge remains very limited.

Although soil biodiversity is linked to numerous ecosystem services, it is still poorly integrated into models and scenarios assessing carbon or biodiversity, as well as in the toolkits needed for forest monitoring. Sustainable soil management, or, more broadly, the multifunctionality of forests, therefore requires in-depth knowledge of this biodiversity. This is a prerequisite for defining appropriate indicators of forest soil health, anticipating soil organism responses and related functions under global change, and contributing to future forest management guidelines.

BOSFOR will provide key knowledge to design sustainable decision-support tools for policymakers and forestry professionals, answering questions such as :

1. What is the diversity, phenology, and activity of organisms in French forest soils ?
2. How can forests be better managed to maintain this biodiversity and the associated ecosystem functions in a changing climate ?
3. How can modelers and stakeholders better account for this biodiversity, improve model predictions, and contribute to more sustainable forest management ?

BOSFOR will enable a unique research effort on forest soil biodiversity, bringing together specialists in soil fauna and microbiota in close collaboration with modelers and stakeholders.

This ambitious, collaborative project will rely on French infrastructures and observatories representing contrasting forest ecosystems. It will involve sixty researchers, engineers, technicians, and early-career scientists from eight different laboratories. The work will be conducted in close interaction with national and international research projects focused on soil biodiversity monitoring and its response to global change.

Through 31 deliverables, BOSFOR will generate key scientific results, including :

1. An updated DNA barcode library and a list of microbial and faunal forest taxa.
2. A standardized system for monitoring forest soil organisms’ presence and activity, based on environmental DNA and acoustic monitoring.
3. Improved understanding of soil biodiversity responses and associated functions to conventional and innovative forest management practices.
4. Insights into soil biodiversity responses to climate change and biomass export.
5. Integration of a soil biodiversity module into carbon and forest dynamics models.
6. Co-construction and evaluation of soil bioindicators with stakeholders.

Finally, BOSFOR will foster collaboration within the forest research community by relying on study sites and experimental plots shared with other projects. The project has been designed to complement and support other PEPR FORESTT projects, with the overarching goal of energizing a broad national network of researchers and forestry actors, thereby promoting more holistic research and opening new scientific frontiers.