Mycorrhizal and rhizospheric fungal community assembly differs during subalpine forest restoration on the eastern Qinghai-Tibetan Plateau

Abstract

Mycorrhizosphere is the interface between roots and soil where a myriad of microorganisms mediate plant growth, nutrient acquisition and tolerance to biotic and abiotic stress, and result in driving ecosystem biogeochemical cycling. Understanding the complexity and dynamics of mycorrhizosphere and its ecology and evolution are critical to enhancing forest productivity and ecosystem functioning, especially in high latitude temperate or high altitude alpine forests. However, the fungal community compositions and their driving ecological mechanisms of mycorrhizosphere during forest restoration are poorly documented. In this study, we simultaneously examined the ectomycorrhizal (EM) and rhizospheric fungal communities of two dominant host tree species (Abies faxoniana and Betula albosinensis) in subalpine forest communities with distinct forest restoration stages (30- vs. 60-year) after clear-cutting. Illumina MiSeq sequencing of internal transcribed spacer 2 (ITS2) sequences was adopted. A total of 1222 EM and 5880 rhizosphere fungal operational taxonomic units (OTUs) were obtained at a 97% sequence similarity level, which were mainly dominated by Basidiomycota. Host identity and forest restoration stage had no significant effects on fungal species richness of both EM and rhizospheric fungi. However, the community assembly of EM and rhizospheric fungi was significantly different during forest restoration, with opposite patterns shown on ectomycorrhizae and rhizosphere. The EM fungal community assembly was significantly affected by host identity, stand age and population dynamic, while the rhizosphere fungal community was significantly structured by combinations of host trees biomass, soil properties and spatial distance. Our data provide important insights that community assembly of EM and rhizosphere fungi may respond idiosyncratically during forest restoration, which will help us deeper understanding forest succession, stability and ecosystem functioning on the Qinghai-Tibetan Plateau.