Résumé
Despite its improtance for human activities, soil biodiversity remains largely unknown and threatened. The French Soil Quality Monitoring Nerwork (RMQS) has a significant impact in removing the grey areas through its survey of soil microorganisms and enzymatic activities.These surveys have deepened our knowledge of the biogeographyof microorganisms, the link with soil use and agricultural pratices, and identified bioindicators of soil quality. But the RMQs could also support long-term monitoring of other components of soil biodiversity.In 2017, the French office for biodiversity expressed the need to buid a survey of soil biodiversity, which will be part of the larger survey of terrestrial biodiversity.A first experimentation based on the monitoring of 30 RMQS sites around France started in 2019, taking into account scientific and practical aspects. Biodiversity sampling was carried out all year long, by the same 12 teams as for the RMQS program, simultaneously with soil sampling and description. Bacteria, fungi and protists were monitored by DNA extraction and sequencing, as well as environmental DNA. Nematodes, mesofauna (particularly springtails), below-ground (earthworms) and surface (beetles and spiders) macrofauna were monitored by sampling and identification of specimens. This study demonstrated the feasibility of monitoring all components of soil biodiversity and lead to the writing of a manual of specifications. However, contrasting to soil microorganisms which can be monitored all along the year, results showed that soil fauna should be monitored during spring.In spring 2024, a second experimentation based on the monitoring of 72 sites will start, involving 3 soil biodiversity experts teams to monitor the same groups as in the first test, from March to June. This experimentation will assess the feasibility of sampling more sites during a shorter period of time. The objective would be to reach the sampling of 180 sites per year, i.e. the routine level of sampling of the second RMQS campaign, to implement a comprehensive monitoring of soil biodiversity for French soils.