Compartmentalized and contrasted response of ectomycorrhizal and soil fungal communities of Scots pine forests along elevation gradients in France and Spain

Fungi are principal actors of forest soils implied in many ecosystem services and the mediation of tree's responses. Forecasting fungal responses to environmental changes is necessary for maintaining forest productivity, although our partial understanding of how abiotic and biotic factors affect fungal communities is restricting the predictions. We examined fungal communities of Pinus sylvestris along elevation gradients to check potential responses to climate change-associated factors. Fungi of roots and soils were analysed at a regional scale, by using a high-throughput sequencing approach. Overall soil fungal richness increased with pH, whereas it did not vary with climate. However, when representative sub-assemblages, i.e. Ascomycetes/Basidiomycetes, and families were analysed, they differentially answered to climatic and edaphic variables. This response was dependent on where they settled, i.e. soil versus roots, and/or on their lifestyle, i.e. mycorrhizal or not, suggesting different potential functional weights within the community. Our results revealed a highly compartmentalized and contrasted response of fungal communities in forest soils. The different response of fungal sub-assemblages indicated a range of possible selective direct and indirect (i.e. via host) impacts of climatic variations on these communities, of unknown functional consequences, that helps in understanding potential fungal responses under future global change scenarios.