Functional diversity of soil macrofauna may contribute to microbial community stabilization under drought stress

Diana Morales-Fonseca¹Sandra Barantal²Francois Buscot³Stephan Hättenschwiler^2,4Alexandru Milcu^2,4Johanne Nahmani^2,4Emmanuel Gritti⁴Kezia Goldmann³Luis Daniel Prada-Salcedo^3*

• ¹University of America, Bogotá, Cundinamarca, Colombia
• ²UPS3248 Ecotron européen de Montpellier, Montferrier Sur Lez, Languedoc-Roussillon, France
• ³Department of Soil Ecology, Helmholtz Centre for Environmental Research, Helmholtz Association of German Research Centres (HZ), Halle (Saale), Germany
• ⁴Université de Montpellier, Montpellier, Languedoc-Roussillon, France

The impacts of climate change, including the increasing frequency and intensity of severe droughts on terrestrial ecosystems, require a better understanding of the interactions between different soil communities to ensure the maintenance of ecosystem functions. However, the extent to which drought-induced changes in microbial communities are influenced by soil biodiversity, particularly the functional diversity of soil macrofauna, remains poorly understood. This study investigated the responses of microbial communities to contrasting functional diversity of soil macrofauna and more severe and prolonged drought in a Mediterranean forest ecosystem under 2 fully controlled conditions. Using 16S amplicon sequencing and inferred functional gene annotations, we assessed microbial responses in a two-year mesocosm experiment using 16 large mesocosms at the Montpellier European Ecotron. Our results showed that the relative abundance of Gram-positive bacterial communities increased compared to Gram-negative ones in response to drought. Furthermore, this study indicates that higher levels of fauna functional diversity may contribute to stabilizing microbial diversity and composition during more severe and prolonged drought. The capacity of microbial communities to face drought conditions was reflected by the enrichment of drought-tolerant genes in specific bacterial taxa. These findings support the need to preserve soil biodiversity to mitigate the effects of future droughts on soil functions.