Rainfall reduction amplifies the stimulatory effect of nitrogen addition on N(2)O emissions from a temperate forest soil

Soil is a significant source of atmospheric N(2)O, and soil N(2)O emissions at a global scale are greatly affected by environment changes that include continuous deposition of atmospheric nitrogen and changing precipitation distribution. However, to date, field simulations of multiple factors that control the interaction between nitrogen deposition and precipitation on forest soil N(2)O emissions are scarce. In this study, we conducted a 2-year continuous assessment of N(2)O emissions from November 2012 to October 2014 at a nitrogen addition and rainfall reduction manipulation platform in an old broad-leaved Korean pine mixed forest at Changbai Mountain in northeastern China. We found that N(2)O emissions from control plots were 1.25 ± 0.22 kg N(2)O-N ha(−1) a(−1). Nitrogen addition significantly increased N(2)O emissions, with the emission factor of 1.59%. A 30% reduction in rainfall decreased N(2)O emissions by 17–45%. However, in combination, nitrogen addition and rainfall reduction increased N(2)O emissions by 58–140%, with the emission factor of 3.19%, and had a larger promotional effect than the addition of nitrogen alone. Our results indicated that drought slightly decreases forest soil N(2)O emission; however, with increasing deposition of atmospheric N in temperate forest soils, the effect of drought might become altered to increase N(2)O emission.