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 N2O emission has been debated, which is possibly related to difference in invasive areas. Therefore, the study investigated N2O 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 N2O emission. The results showed that N2O 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 NH4+-N contents correlated positively with the N2O emission rate (p < 0.05 or p < 0.01). Reversely, urease activity, total nitrogen and NO3- -N contents negatively affected the N2O 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 N2O emission.