The effect of nitrogen (N) deposition on N limitation, phosphorus (P) limitation and the related soil and microbial stoichiometries remains unclear. A simulated nitrogen deposition (SND) experiment (control, ambient, medium and high) and molecular techniques (high-throughput sequencing of 16S and ITS) were conducted to examine the variations in abiotic and biotic properties and to describe the responses of microbial (bacteria and fungi) adaptation strategies in a moso bamboo (Phyllostachys edulis J. Houzeau) forest following SND. Soil water content (SWC) was positively correlated with the microbial community composition. Observed increases in total N and nitrate N contents and decreased ammonia N suggested that SND influenced nitrification. Chao1 and F:B showed that bacteria were more sensitive to SND than fungi. PCoA and linear discriminant analysis (LDA), coupled with effect size measurements (LefSe), confirmed that microbial community composition, including the subgroups (below class level), responded to SND by employing different adaptation strategies. Soil C:N indicated that the soil of the moso bamboo forest was under N limitation prior to SND. The increase in total P (TP), available P (AP) and microbial biomass P (MBP) suggested the acceleration of soil P cycling. Microbial biomass C (MBC) and microbial biomass N (MBN) were not affected by SND, which led to a significant shift in MBC:MBP and MBN:MBP, suggesting that P utilization per unit of C or N was promoted. There was a negative gradient correlation between the fungal community composition and MBC:MBP, while bacteria were positively correlated with MBN:MBP. The results illustrated that the response of fungi to MBC was more sensitive than that of bacteria in the process of accelerated P cycling, while bacteria were sensitive to MBN. Prior to P limitation, SND eliminated the soil N limitation and stimulated soil microorganisms to absorb more P, resulting in an increase in MBP, but did not alter MBC or MBN. This study contributes to our understanding of the adaptation strategies of fungi and bacteria and their responses to soil and microbial stoichiometries.

We analyzed and compared the soil bacterial diversity and difference in community composition in a Moso bamboo forest, a mixed Moso bamboo–conifer (Pinus massoniana) forest, and a coniferous forest. The relative abundances of Acidobacteria and Planctomycetes were significantly lower in the Moso bamboo forest, while those of Actinobacteria, Bacteroidetes, TM‐7 and Chlamydiae were greatly increased. The α‐diversity in the Moso bamboo forest was different from that in the other two forest types but was not statistically distinguished. Principal coordinates analysis suggested that the invasion of Moso bamboo affected the community composition and diversity of soil bacteria. This impact was associated with the soil biochemical environment, as evidenced by increased mean values of soil organic carbon (C) and total nitrogen (N), significant increases in microbial biomass C and N, and a decrease in the NO3−–N content, which indicated that the nitrification rate was reduced in the mixed Moso bamboo–conifer forest. There were no overall correlations between the dominant bacterial phyla and soil biochemical gradients; however, individual dominant phyla correlated with the concentration of N forms, which indicated that the responses of bacteria were sensitive to, and varied depending on, the concentration of soil N forms. In addition, there were correlations between non‐dominant bacterial phyla with respect to operational taxonomic unit proportions <1.0%, and overall gradients of water‐soluble organic N and NO3−–N. The results of this study showed that the changes in soil bacterial flora are associated with the changes in concentration of N forms during the invasion of Moso bamboo.