Figure legends
Figure 1 Platform for nitrogen addition and altered precipitation experiments. (A) Experimental treatments: 1, NP−; 2, NP (CK); 3, NP+ ; 4, N+P−; 5, N+P; 6, N+P+. N: ambient N deposition; P: ambient precipitation; N+: N addition; P−: 50% reduced precipitation; P+: 50% increased precipitation. (B) Experimental site.
Figure 2 Seasonal dynamics of N2O flux and (B) seasonal average N2O flux under different conditions. (C) Changes in seasonal average N2O flux (compared with control) under different treatments. (D) Average N2O flux during the peak period of plant growth. N: nitrogen treatment; P: altered precipitation treatment; N×P: combination of nitrogen addition and altered precipitation. Different letters indicate a significant difference (P < 0.05). Error bars represent the standard error.
Figure 3 Effects of nitrogen addition and altered precipitation on abundances of functional genes. (A) ammonia-oxidizing archaea (AOA); (B) ammonia-oxidizing bacteria (AOB); (C) nirS ; (D) nirK ; (E) nosZ . N: nitrogen treatment; P: altered precipitation treatment; N×P: combination of nitrogen addition and altered precipitation. Different letters indicate a significant difference (P < 0.05). Error bars represent the standard errors of the means (n = 5).
Figure 4 Relationships between the N2O flux and abiotic properties. Regression lines are only shown when significant (P< 0.05).