The short-term effect of simulated acid rain and nitrogen deposition on the soil microbial functional profile targeting C, N, and P cycling

Acid rain and nitrogen deposition resulting from fossil fuel combustion and atmospheric NH3 enrichment have inflicted significant damage to ecosystems on a global scale. However, their specific impacts on forest soil ecosystems, particularly in soil carbon (C), nitrogen (N), and phosphorus (P) cycling, remain unclear. For this study metagenomic sequencing was employed to study the effects of simulated acid rain and nitrogen deposition on microbial functional genes in a subtropical plantation in the Yangtze River Delta region. Our findings indicated that acid rain and nitrogen deposition did not have significant impacts on overall functional Shannon diversity. However, acid rain treatments did alter microbial functional structures, particularly as relates to C, N, and P cycling. Notably, the soil pH had a significant correlation with microbial functional profiles. In the absence of nitrogen deposition, acid rain led to an increase in the relative abundance of starch and carbon monoxide (CO) oxidation processes, while reducing the relative abundance of multiple systems and reductive tricarboxylic acid (rTCA) pathway processes. Further, acid rain decreased the relative abundance of nitrogen fixation and nitrification processes, as exemplified by hao, nirK, and norZ genes, while increasing the relative abundance of norC and narI genes. Additionally, acid rain was associated with a decrease in the relative abundance of P starvation regulation and inorganic P solubilization processes. However, N deposition did not have a significant effect on microbial functional processes related to C, N, and P cycling. Our study emphasized the negative impacts of short-term acid rain on soil N and P cycling in a subtropical plantation, which surpassed that of short-term N deposition.