Sensitivity of soil fungal and bacterial community compositions to nitrogen and phosphorus additions in a temperate meadow

Soil microorganisms play key roles in soil nutrient turnover and plant community composition; however, the soil microbial community composition and species diversity are often influenced by nutrient enrichment which may affect how soil microbes influence nutrient cycles and the plant community structure. The resistance of soil fungal and bacterial communities to nitrogen (N) and phosphorus (P) additions and whether the responses of the soil microbes and the plant community are simultaneous in a N-limited temperate meadow ecosystem are still unclear. We carried out a 7-year experiment with N and P additions in a temperate meadow. The community structures of soil bacteria and fungi were examined based on high-throughput sequencing targeting the 16S rRNA and ITS genes, respectively. Nitrogen addition did not influence the community composition or species richness of bacteria, but it did alter the soil fungal community composition and increased fungal operational taxonomic unit (OTU) richness. Phosphorus addition significantly altered the soil fungal and bacterial community compositions, decreased the richness of bacterial OTUs, and increased the OTU richness of fungi. Proteobacteria (38.5%) and Acidobacteria (22.3%) were the most dominant bacteria. Ascomycota were the dominant fungi (42.6%) across all samples. The enrichment of available P in the soil due to P addition reduced the bacterial β-diversity, while the β-diversity of soil fungi was mainly influenced by the concentrations of soil N and P, as well as soil moisture. The sensitivity of soil fungi and bacteria to P addition was stronger than that of N addition, and the response of the soil microbes to N and P additions was more sensitive than that of the plant community. Our results highlight the unequal sensitivity of the soil fungal and bacterial community composition and structure to N and P additions, thereby causing changes in above and belowground community composition and structures in the studied temperate meadow ecosystem.