Source: French to English Tester Published on: 2026-04-20
Source: The Conversation – in French– By Mickaël Hedde, Research Director, Inrae
The European directive on soil monitoring, adopted by the European Union at the end of 2025, aims to achieve healthy soils by 2050. Soils are indeed at the crossroads of multiple issues: climate, biodiversity, food, etc. Yes, but with what measurement tools? The text decided in Brussels only currently mandates the approach based on environmental DNA. However, France has strong experience in measuring soil quality, which could be advantageously utilized: the best monitoring tools are those that simultaneously integrate several complementary approaches.
Since November 2025, the European Directive onsoil monitoring and resiliencerequires Member States to regularly assess soil biodiversity. For the biological part, the directive provides for monitoring every six years,microbial diversity of soils(bacteria and fungi) fromenvironmental DNA(ADNe).
However, while eDNA is a powerful tool for detecting biodiversity on a large scale, it is insufficient on its own to interpret the observed changes and identify their causes. Indeed, bacterial and fungal communities represent only a part of soil biodiversity, which also includes many organisms with crucial and varied ecological roles.
Soil functioning also relies on the abundance, biomass, and activity of living organisms, aspects that cannot be assessed solely by molecular detection. A graduated approach combining several complementary protocols is therefore necessary to produce robust and useful indicators for public action.
The French experience, notably through the soil quality measurement network (RMQS) and theGIS Sol, constitutes, in this capacity, a reference framework for the interpretation of results and a proven operational framework for soil biodiversity monitoring. This could usefully complement the foundation provided by European legislation.
Environmental DNA, necessary but not sufficient
TheDNAis a molecular approach and, as such, offers advantages in environmental monitoring: broad – and a priori standardized – detection of biodiversity, high spatial and temporal comparability… Such methods constitute a particularly effective tool for detecting changes in the composition of biological communities.
However, molecular signatures derived from eDNA do not always allow for the accurate identification of taxa present in soils. They may exhibit biases ofrepresentativeness. They are, moreover, often weakly correlated with other essential biological characteristics used to characterize biodiversity and soil functioning, such as the abundance of organisms, their biomass, their demographic structure, or their activities. They will therefore provide an incomplete — and sometimes even distorted — view of soil health.
However, beyond simply detecting changes in diversity, monitoring systems must also allow for the interpretation of these changes, that is, understanding what they imply for soil functionality, for example in agriculture, and identifying their causes. This is what will enable the evaluation of the effectiveness of public policies and management practices. In this context, reducing the biological and ecological complexity of soils to this single component carries a risk related to the difficulties of interpretation.
The directive nevertheless provides that Member States may supplement the mandatory indicators with other biological indicators in their national monitoring systems, thereby opening the possibility for more integrated approaches.
A tool for public decision-making assistance
Environmental monitoring pursues two distinct and complementary objectives: detecting changes in the state of ecosystems and attributing these changes to environmental pressures, land uses, or management practices. These two dimensions are closely linked by the biological and ecological processes that structure the functioning of ecosystems.
Beyond their scientific scope, the indicators used to monitor soil biodiversity constitute a tool to aid public decision-making. It is not only about identifying the dynamics of biological communities but also understanding their causes. This therefore concerns, first and foremost, public decision-makers. The aim is to guide sustainable planning and management practices, to identify degradation situations, to implement policies to address them, and to be able to evaluate their effectiveness.
A monitoring system limited to detecting changes in soil biodiversity without enabling their interpretation and attribution to environmental pressures would provide only a limited basis for evaluating public policies and implementing appropriate management strategies.
Biodiversity is not reduced to the number of taxa alone
The ecological functions of the soil – such as the regulation of water and contaminants, the provision of nutrients, carbon storage, maintenance of structure, or the support of biodiversity itself – are not static states, but dynamic processes. They rely on the activity of living organisms, their biomass and their functional characteristics (physiology, behavior) as well as their interactions (competition, symbiosis, parasitism). They manifest through fluxes and renewal rates rather than simple stocks.
In this context, molecular approaches provide valuable information about the presence of organisms but do not, by themselves, allow for the evaluation of these dynamic processes or their intensity. A correct interpretation of soil functioning therefore requires additional measurements as well asinterpretation frameworksallowing to link biological indicators to the different land use contexts and environmental conditions.
Environmental DNA data are increasingly used to develop new approaches, for example those based oninteraction networks, which allow representing the organization of soil biological communities. When these networks are built solely from presence or co-occurrence data, they mainly reflect the sharing of ecological conditions or environmental niches by different species.
This then only provides indirect information about the biological activities at work and the flows of matter and energy, which also determine the functioning of soils. Ecological interpretation requires additional information, particularly about the abundance or biomass of organisms. This is how biological communities can be linked to the ecological processes that support soil functions.
A graduated and complementary approach
In order to reconcile operational efficiency and ecological relevance, soil biodiversity monitoring is increasingly combining several types ofapproaches, each providing specific information about the state and functioning of biological communities.
DNA-based approaches allow for broad and standardized detection of microbial biodiversity, and could be extended to other organisms such as invertebrates.
Other methods are based on the direct observation of soil fauna organisms, the estimation of their abundance or biomass, or the analysis of their functional characteristics. They provide essential information on the biological structure and ecological role of soil communities.
These approaches should not be considered mutually exclusive, but as complementary tools. They allow linking the composition of biological communities (taxonomic and functional structure) to the ecological processes that support soil functions. Their combination is, in this respect, particularly interesting for building a monitoring strategy presenting different levels of information.
This logic of complementarity is already being implemented in some existing monitoring systems. For example, within the framework of the French soil monitoring network (RMQS) or in the mountain biodiversity observatoryOrchamp. These approaches are not meant to be deployed everywhere, but their combination is essential to correctly interpret the state and evolution of soil biodiversity.
Our recommendations for the implementation of the directive at the national level
Preserving the capacity to understand, explain, and act requires recognizing that the biological complexity of soils calls for a controlled diversity of monitoring approaches.
With the support ofGIS Sol, France is among the nations at the forefront of soil biodiversity monitoring. It has tested this approach, combiningseveral protocols within the RMQS, for several years. This experience, rare at the European level, must serve as the foundation on which to build the future national soil monitoring network.
The directive provides, beyond the mandatory indicators, the possibility for Member States to supplement their systems with optional indicators. This flexibility offers the opportunity to establish a monitoring system capable not only of detecting trends in soil biodiversity evolution, but also of interpreting their causes and possibilities.remediation. This finally allows for the assessment of the implications for public policies.
In this perspective, several principles should guide the national implementation of the European directive:
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Do not restrict national soil biodiversity monitoring to a single measure derived from eDNA, which limits our ability to interpret the observed changes.
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Implement a combination of complementary measures, enabling the connection of biodiversity detection to community structure and ecological processes that support soil functions, with the support of protocols and measures that will be developed in the PEPR.DynabiodandLivingSoils.
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Develop interpretation frameworksopenand analytical frameworks that allow evaluating whether the observed variations are significant, in order to link biological indicators to land use and environmental pressures.
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Make use of existing mechanisms, notably the RMQS supported by the GIS Sol, in order to ensure the coherence, comparability, and scientific robustness of the future national surveillance system.
This article is a joint production of the RMQS Biodiversity, the PEPR SolsVivants and Dynabiod, and the RNEST, represented by the co-authors. The elaboration of this document was also contributed to by: Apolline Auclerc, Nolwenn Bougon, Miriam Buitrago, Philippe Hinsinger, Claudy Jolivet, Antoine Lévêque, Gwenaël Magne, Florence Maunoury-Danger, Jérôme Mathieu, Christian Mougin, Laurent Palka, Benjamin Pauget, Guénola Pérès, Sophie Pouzenc, Sophie Raous, Claire Salomon, Marie-Françoise Slack, Wilfried Thuiller, Cécile Villenave, Quentin Vincent.
Mickaël Hedde has received funding from various French organizations (OFB, ANR, ADEME) and the European Union (Horizon Europe) to conduct his research at INRAE.
Antonio Bispo is the director of the INRAE Info&Sols research unit based in Orléans. He has received funding from various French organizations (Ministries, OFB, ANR, ADEME, Centre Val de Loire Region) and from the European Union (Horizon Europe) to conduct his research. The research unit leads, on behalf of the GIS Sol (www.gissol.fr), the national soil inventory and monitoring programs, it also manages the national soil information system.
Claire Chenu is a member of the French Association for Soil Study (AFES), a corresponding member of the Academy of Agriculture, and a member of the Academy of Technologies. She co-chairs the Scientific, Technical, and Innovation Committee of the National Network for Scientific and Technical Expertise on Soils (CSTI RNEST). She has received European funding (particularly from the European Joint Programme SOIL) to conduct research within INRAE and AgroParisTech.
Flavien Poincot is an engineer at Acta who supports, facilitates, and represents the network of 19 agricultural technical institutes, applied research organizations working for all agricultural, animal, and plant productions.
Jérôme Cortet is a member of the French Society of Evolutionary Ecology (SFE2) and of the French Association for Soil Study (AFES). He currently co-chairs the Scientific, Technical and Innovation Committee of the National Network for Scientific and Technical Expertise on Soils (CSTI RNEST). He has received funding from various French organizations (ANR, ADEME, Occitanie Region) to conduct his research within the Center for Functional and Evolutionary Ecology, a laboratory affiliated with the University of Montpellier Paul-Valéry.
–ref. European Directive on soils: why monitoring by environmental DNA will not be enough –https://theconversation.com/eu-soil-directive-why-monitoring-by-environmental-dna-will-not-be-enough-280098