Multifunctionality is known to evolve during primary ecosystem succession, for instance, after glacier retreat. Yet, what exactly trigger an increase in multifunctionality as ecosystem develops is less understood. Here we evaluated the contribution of soil multitrophic richness, functional composition and biotic coupling of food webs as predictors of soil multifunctionality (14 functions for nutrient stocks and biomass accumulation) in a well-characterized 120-year chronosequence of glacier retreat. Our results indicated that the tightness of soil food web coupling increased during primary succession and strongly co-occurred with changes in soil multifunctionality. Furthermore, the shifts in energy and nutrient fluxes served as the fundamental links between biodiversity and ecosystem functioning. Thus, multitrophic diversity facets, including taxonomic richness and functional composition, as well as food web coupling for energy and nutrients orchestrated soil multifunctionality development. Our work provides a comprehensive perspective for elucidating the multitrophic diversity and multifunctionality changes during the first stages of ecosystem development in a context of global warming.

Understanding how the network structure of plant and microbiota interactions differ along ecological gradients is of great interest. We studied network patterns at 60 sites across the Tibetan Plateau, representing a gradient in both precipitation and plant species richness. The number of fungal OTUs that were uniquely connected to each plant species in the plant-fungi network was most strongly positively related to plant species richness. By contrast, the number of unique bacterial OTUs linked to each plant species decreased with increasing plant species richness. The number of fungal OTUs specifically linked to each plant species was positively related to plant species richness, and to productivity. We suggest that in a more extreme high-stress environment that decreases plant species richness, plants and fungi have fewer excess resources to invest in specific relationships, showing up as lower associated microbiome richness, with bacteria may partially replacing this role in high stress/low productivity environments.

The development of high-throughput sequencing (HTS) technologies has greatly improved our capacity to identify fungi and unveil their ecological roles across a variety of ecosystems. Here we provide an overview about current best practices in metabarcoding analysis of fungal communities, from experimental design through molecular and computational analyses. By re-analysing published datasets, we find that operational taxonomic units (OTUs) outperform amplified sequence variants (ASVs) in recovering fungal diversity, which is particularly evident for long markers. Additionally, analysis of the full-length ITS region allows more accurate taxonomic placement of fungi and other eukaryotes compared with the ITS2 subregion. We conclude that metabarcoding analyses of fungi are especially promising for co-analyses with the functional metagenomic or transcriptomic data, integrating fungi in the entire microbiome, recovery of novel fungal lineages and ancient organisms as well as barcoding of old specimens including type material.