Long-Term Nitrogen Addition Exerts Minor Effects on Microbial Community but Alters Sensitive Microbial Species in a Subtropical Natural Forest

Increasing nitrogen (N) deposition profoundly affects nutrient cycling in soil, thereby influencing forest ecosystem productivity and function. Soil microorganisms are integral driving turnover; the changes microbial communities response to N associated soil availability, especially of limited nutrients, far from clear. To explore bacterial fungal their key environmental drivers under deposition, we conducted a multilevel field addition experiment Castanopsis carlesii natural forest. properties were investigated. There no significant alpha diversities (presented as Chao1 Shannon’s indexes) beta bacteria fungi among three treatments. Consistently, relative abundances dominant phyla (i.e., Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Planctomycetes) Basidiomycota, Ascomycota, Rozellomycota) did not change following addition. These results suggest that alter community diversity structure. In addition, Mantel test showed pH, NO3−-N, dissolved organic (DON), total phosphorus (TP) predominantly influenced structure bacteria, but fungi. Meanwhile, abundance some sensitive genera, such Bryobacter, Bradyrhizobium, Sorangium, Archaeorhizomyces, significantly decreased. indicate decreased ability for fixation P mobilization induced by deposition. Moreover, there relationships between Archaeorhizomyces NO3−-N available (AP), suggesting responses groups likely depend on nutrients or P. Collectively, 6 years had influence communities, with turnover. This finding emphasizes critical roles species meditating climate change.