Contrasting patterns and co-occurrence network of soil bacterial and fungal community along depth profiles in cold temperate montane forests of China

Abstract

Soil bacterial and fungal communities with different key ecological functions play an important role in the boreal forest ecosystem. Despite several studies have reported the microbial altitudinal distribution patterns, our understanding about the characteristics of the microbial community and the core composition of the microbiome in cold-temperate mountain forests is still limited. In this study, Illumina MiSeq sequencing was used to investigate the changes in soil bacterial and fungal communities in surface and subsurface soils along at an altitudinal gradient (from 830 m to 1300 m) on Oakley Mountain in the northern Greater Khingan Mountains. Altitude and soil depth had significant impacts on the relative abundance of Proteobacteria, Acidobacteria and Actinobacteria (dominant phylum for bacteria), and altitude had significant impacts on the Ascomycota, Basidiomycota and Mucoromycota (dominant phylum for fungi). The diversity of bacterial and fungal communities showed a monotonous decrease and increase with altitude. The influence of altitude on bacterial and fungal community composition was greater than that of soil depth. The variation of pH and dissolved organic nitrogen (DON) content in different altitudes were the main factors driving the bacterial and fungal community structure, respectively. There is no obvious difference between the network structure of surface and subsurface soil fungal communities, while the network of subsurface soil bacterial communities was more complex and compact than the surface layer. The network nodes mainly belonging to Proteobacteria and Actinobacteria are the key species in the two soil layers. Our results demonstrated that the altitude had a stronger influence on soil bacterial and fungal communities than soil depth, and bacterial and fungal communities showed divergent patterns along the altitudes and soil profiles.