Networks depicting the fine-scale co-occurrences of fungi in soil horizons

Fungi in soil play pivotal roles in nutrient cycling, pest controls, and plant community succession in terrestrial ecosystems. Despite the ecosystem functions provided by soil fungi, our knowledge of the assembly processes of belowground fungi has been limited. Based on the high-throughput sequencing data of fungi in a cool temperate forest in northern Japan, we analyze how taxonomically and functionally diverse fungi show correlated fine-scale distributions in soil. By uncovering pairs of fungi that co-occurred in the same soil samples more/less frequently than expected by chance, networks depicting fine-scale distributions of fungi are inferred at the O and A horizons. The results then leads to the working hypothesis that mycorrhizal, endophytic, saprotrophic, and pathogenic fungi as well as fungi with unknown functions form compartmentalized networks of potential facilitative, antagonistic, and/or competitive interactions in belowground ecosystems. Overall, this study provides a research basis for further understanding how interspecific interactions, along with sharing of niches among fungi, drive the dynamics of poorly explored biospheres in soil.