N: nitrogen treatment; P: altered precipitation treatment; N×P: combination of nitrogen addition and altered precipitation. AGB: aboveground biomass; BGB: belowground biomass. Data are represented by mean ± SE (n = 5). Bold values indicate that treatment effects are significant (P < 0.05). Different lowercase letters indicate significant difference (P < 0.05). The block was used as a random factor in the two-way ANOVA.

Table 3 Pearson correlation analysis of the relationships between N₂O flux and functional genes abundance (n = 30 for N₂O flux and functional gene, significance: *P < 0. 05; ** P < 0.01)