Plant Diversity is Coupled with Soil Fungal Diversity in a Natural Temperate Steppe of Northeastern China

Soil fungi and aboveground plant play vital functions in terrestrial ecosystems, while the relationship between aboveground plant diversity and the unseen soil fungal diversity remains unclear. We established 6 sites from the west to the east of the temperate steppe that vary in plant diversity (plant species richness: 7–32) to explore the relationship between soil fungal diversity and aboveground plant diversity. Soil fungal community was characterized by applying 18S rRNA gene sequencing using MiSeq PE300 and aligned with Silva 132 database. As a result, soil fungal community was predominately composed of species within the Ascomycota (84.36%), Basidiomycota (7.22%) and Mucoromycota (6.44%). Plant species richness occupied the largest explanatory power in structuring soil fungal community (19.05%–19.78%). The alpha (α) diversity of the whole soil fungi and Ascomycota showed a hump-backed pattern with increasing plant species richness, and the beta (β) diversity of the whole soil fungi and Ascomycota increased with increasing plant β diversity. Those results indicated that soil fungi and external resources were well balanced at the 20-species level of plant and the sites were more distinct in the composition of their plant communities also harbored more distinct soil fungal communities. Thus, plant diversity could predict both soil fungal a and β diversity in the temperate steppe of northeastern China.