Habitat and host specificity of the rhizosphere fungi form meta-community structure of the Arctic glacial forefield

The ongoing retreat of glaciers under global warming provides a new opportunity for tundra species to expand their habitats. We investigated the diversity of the fungal community surrounding the rhizome across five successional stages and four host plant species in Ny-Ålesund and Svalbard to understand the assemblage process of the underground community in a glacial forefield. From the meta-barcoding data, habitat- and host-specific species were statistically identified to gain a deeper understanding of the assembly mechanisms, and their influence on the meta-community structure among various successional stages or host plants was assessed. Habitat-specific species reduced during the early succession stages, whereas host-specific species remained constant irrespective of the successional stage. These trends resulted in a relative increase in host-specific species during the early stages, indicating that plant diversity is more crucial for rhizosphere communities in newer habitats. Rhizosphere communities in each host showed distinct responses along the successional gradient, depending on the plant–microbe interactions, such as mycorrhizal types. These various responses are presumed to contribute to the heterogeneity of rhizosphere communities during the early succession stages. Integrating plant–rhizosphere–microbe interactions into successional frameworks is necessary for understanding and predicting ecosystem development in Arctic landscapes, as climate warming accelerates glacier retreat, bare-ground expansion, and biological invasion.