Characteristics of bulk and rhizosphere soil microbial community in an ancient Platycladus orientalis forest

Soil microbial community composition and diversity were significantly affected by tree species, growth stage and soil nutrients in the forest ecosystem. We analyzed the bulk and rhizosphere soil microbial communities associated with young (20 year) and old (1000 year) trees of Platycladus orientalis using 16S and ITS rRNA high-throughput gene sequencing techniques. Platycladus orientalis growth altered the nutrient and microbial community compositions in the bulk and rhizosphere soils. In a typing analysis, the bacterial and fungal communities clustered into two and three groups, respectively, and only the fungal diversity exhibited significant differences between the bulk and rhizosphere soils. Soil microbial community compositions in bulk and rhizosphere soils were dominated by Acidobacteria, Proteobacteria, Actinobacteria and Ascomycota phyla, and their changes were driven by the Gemmatimonadetes, Nitrospirae, Planctomycetes, Zygomycota and Basidiomycota phyla. Compared with soils under young trees, 24.63% and 72.80% of the bacterial and fungal genera in bulk soil and 24.78% and 59.92% of the bacterial and fungal genera in rhizosphere soil shifted in the old trees samples. Soil microbial community compositions were sensitive to changes of soil nutrients, which explained 82.10% and 86.79% of the total variation in the major bacterial and fungal genera community compositions, respectively. Our results suggest that long-term growth of Platycladus orientalis trees significantly altered bulk and rhizosphere microbial community compositions, and its influence was greater on the fungal community than on the bacterial community.