Changes in soil bacterial communities in an evergreen broad-leaved forest in east China following 4 years of nitrogen addition

Purpose Evergreen broad-leaved forest ecosystems are common in east China, where they are both ecologically and economically important. However, nitrogen (N) addition over many years has had a detrimental effect on these ecosystems. The objective of this research was to evaluate the effect of 4 years of N addition on microbial communities in an evergreen broad-leaved forest in southern Anhui, China. Materials and methods Allochthonous N in the form of aqueous NH 4 NO 3 and phosphorus (P) in the form of Ca(H 2 PO 4 ) 2 ·H 2 O were applied at three doses with a control (CK, stream water only without fertilizer): low-N (50 kg N ha −1 year −1 ), high-N (100 kg N ha −1 year −1 ) and high-N+P (100 kg N ha −1 year −1 + 50 kg P ha −1 year −1 ). Quantitative PCR analysis of microbial community size and Illumina platform-based sequencing analysis of the V3-V4 16S rRNA gene region were performed to characterize soil bacterial community abundance, structure, and diversity. Results and discussion Bacterial diversity was increased in low-N and high-N treatments and decreased in the high-N+P treatment, but α-diversity indices were not significantly affected by N additions. Proteobacteria, Acidobacteria, and Actinobacteria were the predominant phyla in all treatments, and the relative abundance of different genera varied among treatments. Only soil pH ( P = 0.051) showed a weak correlation with the bacterial community in CK and low-N treatment. Conclusions The composition of the bacterial community and the abundance of different phyla were significantly altered by N addition. The results of the present study indicate that soil bacterial communities in subtropical evergreen broad-leaved forest are, to a certain extent, resilient to changes derived from N additions.