How Tree Communities Shape the Underground Functioning of European Forests

Source: French to English Tester   Published on: 2026-05-21

Source: The Conversation – in French– By Ludovic Henneron, Associate Professor in Ecology, University of Rouen Normandy

Ecosystems worldwide are rapidly evolving under the pressure of global changes such as climate warming, land use changes, or biological invasions, but what happens underground remains poorly understood. It is known, for example, that plants play a central role in “trophic networks,” these sets of food-related interactions among living beings in an ecosystem. However, we still poorly understand how plant communities, such as the tree species in a forest, influence the circulation of matter and energy through trophic interactions among soil organisms, such as microbes (fungi and bacteria) and detritivore, herbivore, and carnivore fauna.
In our recent study, published on April 6 inNature, we focused on 64 European forests, on the tree species found there, and on the question of how these influence the activity of the soil trophic network in terms of energy flow within it.
We have discovered that forests dominated by tree species prioritizing the acquisition of resources (water, nutrients, and light) and thus capable of rapid growth, such as the common hornbeam (Carpinus betulus) or the warty birch (Betula pendula), show a higher activity of the soil trophic network. These trees indeed provide more fresh organic matter of good nutritional quality and create warmer microclimates, stimulating the metabolism of soil organisms and accelerating processes such as the decomposition of organic matter and the recycling of soil nutrients.
Conversely, forests dominated by tree species that prioritize resource conservation, such as Scots pine (Pinus sylvestris) or the Norway spruce (Picea abies), and whose growth capacity is therefore slower, exhibited lower activity of the soil trophic network.
In other words, species identity and their “functional traits” linked to their resource allocation strategy within a tree community are more important than previously thought.
Surprisingly, simply mixing different tree species did not improve soil function—and often slightly reduced it—despite the increase in aboveground tree growth induced by this diversification. This discrepancy highlights a crucial point: what benefits the trees on the surface does not always benefit the belowground trophic network.
Why is it important?
These results have important implications for forest management. Promoting tree diversity alone might not be sufficient to maintain healthy soils, that is, capable of functioning to ensure the provision of multiple services benefiting humanity. On the other hand, selecting tree species based on their functional traits, such as their metabolic activity or growth capacity, could prove more effective in preserving the vitality of forest ecosystems.
In the future, climate change is expected to increase the frequency and intensity of droughts, thereby favoring tree species that prioritize resource conservation, as they aremore resistant to mortality caused by cavitation induced by water stress. Our findings suggest that this change in the species composition of tree communities could slow soil functioning, with significant repercussions for the recycling of soil organic matter, nutrient availability, and forest regeneration. Overall, the study highlights the need to consider both aboveground and belowground dynamics in forest management in the face of climate change.

What are the follow-ups?
This research paves the way for multiple research perspectives.
It would thus be interesting to study these tree communities and the functioning of the soil trophic network of these forests repeatedly over time, in order to monitor the joint temporal dynamics of aboveground and underground behaviors in relation to ongoing global changes. This would allow for a better understanding of the causal links involved.
This research work also raises questions concerning the relative importance for soil organism nutrition of different food sources supplied at the base of the trophic network by plants. Among these are litters, which constitute the dominant input of plant material in the form of dead leaves, roots, and stems requiring decomposition to be consumed. There are also living roots, which can be directly consumed by herbivores or pathogens but also provide fresh organic matter to the soil in soluble form directly accessible to soil organisms through a phenomenon called “rhizodeposition.”

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The projectSoilForEUROPE(ANR-16-EBI3-0009) is supported by the National Research Agency (ANR), which funds project-based research in France. The ANR’s mission is to support and promote the development of fundamental and applied research across all disciplines, and to strengthen the dialogue between science and society. For more information, visit the website of theANR.

Ludovic Henneron received funding from the ANR (2024 Generic Call for Projects, Young Female Researchers and Young Male Researchers project) for the PLASTRAIT project (Plasticity of the quality of tree leaf litter: consequences for soil nitrogen recycling and plant-plant interactions).

Paul Kardol received funding from the BiodivERsA COFUND call for research proposals, with the national funders Agence Nationale de la Recherche (ANR, France), the Belgian Science Policy Office (BELSPO, Belgium), Deutsche Forschungsgemeinschaft (DFG, Germany), the Research Foundation Flanders (FWO, Belgium), the Swedish Research Council (FORMAS, Sweden).

Stephan Hattenschwiler received funding from the BiodivERsA COFUND call for research proposals, with the national funders Agence Nationale de la Recherche (ANR, France), the Belgian Science Policy Office (BELSPO, Belgium), Deutsche Forschungsgemeinschaft (DFG, Germany), the Research Foundation Flanders (FWO, Belgium), the Swedish Research Council (FORMAS, Sweden) and the French exploratory program (France 2030) FairCarboN (ANR-22-PEXF-0001).

David Wardle does not work for, advise, hold shares in, or receive funds from any organization that could benefit from this article, and has declared no other affiliation than his research institution.

–ref. How tree communities shape the underground functioning of European forests –https://theconversation.com/how-tree-communities-shape-the-underground-functioning-of-european-forests-282772