Soil fungal community structure and functional fungal biomass were different in Korean pine plantations with different simulated nitrogen deposition concentrations

Nitrogen (N) deposition is a global environmental issue that can have significant impacts on the structure and function of ecosystems. Fungi are key players in soil biogeochemical cycles and their community composition and diversity are tightly linked to the health and productivity of forest ecosystems. Based on high-throughput sequencing and ergosterol extraction, we examined soil fungal diversity, community composition, and functional fungal biomass in a Korean pine plantation after 8 years of continuous N application. We examined the changes in community structure and biomass of ectomycorrhizal (ECM) and saprophytic (SAP) fungi in 0-10 cm soil of Korean pine plantation under N addition and their driving factors. The co-occurrence network of soil functional fungal communities was constructed to show the co-occurrence pattern of soil fungal communities. Our results showed that N application increased fungal community richness, with the highest richness and Chao1 index under the low N treatment (LN: 20 kg N ha-1 yr-1). FUN Guild analysis shows that the relative abundance of the ECM fungi and SAP fungi increased before they were reduced. The molecular ecological network analysis based on random matrix theory (RMT) showed that the interaction between ECM and SAP fungi was enhanced by N application, and the interaction was mainly positive in the ECM fungal network. N application increased fungal biomass, and the total fungal biomass was the highest under the MN treatment. Soil effective N of ECM fungi biomass is greater than the effect on SAP fungal biomass.Overall, we concluded that N addition changed soil biochemical parameters, increased fungal activity, and enhanced functional fungal interactions in the Korean pine plantation over an 8-year simulated N addition. We need to consider the influence of soil fungi in complex soil conditions and to emphasize forest management control soil fungi community structure and biomass of the consequences. The results could provide a reference for reducing the impact of increasing N deposition on forest soil.