Nitrous oxide emission rate in response to plant, soil and microbial properties in marshes impacted by alien Spartina alterniflora

The effect of Spartina alterniflora (thereafter, abbreviated as Spartina ) invasion on N 2 O emission has been debated, which is possibly related to difference in invasive areas. Therefore, the study investigated N 2 O emission rate using invasive gradients (native, native- Spartina coexisted and Spartina -dominated vegetations) and areas (Sanmen, Linhai and Jiaojiang) as fixed factors. Meantime, plant, soil and microbial parameters were determined for analyzing the mechanisms behind the N 2 O emission. The results showed that N 2 O emission rate significantly increased with Spartina invasion ( p < 0.05), and was also impacted by invasive area ( p < 0.05), as shown by two-way analysis of variance. Redundancy analysis showed that plant biomass, microbial biomass, potential denitrification rate, nitrate reductase activity, pH, soil organic carbon and NH 4 + -N contents correlated positively with the N 2 O emission rate ( p < 0.05 or p < 0.01). Reversely, urease activity, total nitrogen and NO 3 − -N contents negatively affected the N 2 O emission rate ( p < 0.05). These results suggest that except for Spartina invasion gradient, the invasive area is also a crucial factor in mediating soil N 2 O emission.