Nitrogen deposition weakens the stimulatory effect of Moso bamboo ( Phyllostachys edulis ) leaf litter on soil CO 2 emissions

Purpose The effects of nitrogen (N) deposition and leaf litter addition on soil carbon (C) cycling have been widely studied. However, soil carbon dioxide (CO 2 ) emissions linked to N deposition, leaf litter decomposition, soil microbial biomass, and enzyme activity remain poorly understood. Therefore, the objective of this study was to investigate the interactive effects of N and leaf litter addition on soil CO 2 emissions. Materials and methods We conducted a 180-day laboratory incubation experiment by adding Moso bamboo ( Phyllostachys edulis ) leaf litter and ammonium nitrate (NH 4 NO 3 , equivalent to 50 kg N ha −1 yr −1 ), both alone and in combination with one another, to the soil collected from a Moso bamboo forest in subtropical China. Results and discussion After 180 days of incubation, the sole leaf litter addition significantly increased cumulative soil CO 2 emissions by 207%, whereas the sole addition of N did not significantly affect. However, the combined effect of N and leaf litter addition on soil CO 2 emissions was antagonistic. The addition of leaf litter alone enhanced dissolved organic C (DOC), total inorganic N, and microbial biomass C (MBC) concentrations in the soil. Nonetheless, the combined addition of N and leaf litter reduced lignin decomposition, soil MBC concentration, soil DOC, and soil C-degrading enzyme activities in comparison to leaf litter addition alone. Conclusions The present study indicates that although the addition of leaf litter stimulates soil CO 2 emissions, the deposition of atmospheric N can reduce this stimulatory effect and promote lignin accumulation in Moso bamboo forest soils.