Simulated nitrogen deposition alters the ectomycorrhizal fungal community structure in northern Korean pine plantations

Northern temperate forests are sensitive to nitrogen deposition. Korean pines are the zonal dominant vegetation in these forest ecosystems and a typical obligate ectomycorrhizal (ECM) tree. However, the impact of varying nitrogen additions on the ectomycorrhizal fungal (ECMF) community structure in Korean pine plantations remains unclear. In this experiment, nitrogen deposition was simulated (CK = 0 kg N ha−1 yr−1, LN = 20 kg N ha−1 yr−1, MN = 40 kg N ha−1 yr−1, HN = 80 kg N ha−1 yr−1), and soil biochemical indicators, ECMF community composition, and diversity were measured. The results showed that high nitrogen addition led to increased ECMF colonization, decreased ECMF community diversity and richness, and altered the occurrence of biomarkers. The MN treatment significantly increased the Simpson index compared to the LN treatment (P < 0.05), with Amphinema sp, Tuber sp, and Tylospora asterophora identified as biomarkers in the CK, LN, and HN treatments, respectively. The HN treatment significantly reduced the Chao1 index (P < 0.05), with Inocybe quietiodor, Tarzetta catinus, Inocybe giacomi, and Russula viscida serving as biomarkers in the CK, LN, MN, and HN treatments, respectively. Nitrogen addition led to decreased soil pH and available phosphorus content, increased ammonium nitrogen content, and affected ectomycorrhiza colonization by altering the soil ECMF community structure. Among these factors, ammonium nitrogen was the most influential in changing the ECMF community structure. This research offers valuable data to help predict changes in ECMF community structure in Korean pine plantations as nitrogen additions increase.