Effects of Spartina alterniflora invasion on methane emission in coastal salt marsh.

: To investigate the effects of Spartina alterniflora invasion on methane emission from coastal salt marsh, three S. alterniflora invasive levels were established nearby Taizhou City of Zhejiang Province, including native community, mixed community with S. alterniflora and native weeds, and mono-community of S. alterniflora. The results showed that the CH4 flux in the three communities ranged from 0.68 to 5.88 mg·m-2·h-1, and CH4 flux increased significantly with S. alterniflora invasion. CH4 flux in the mono-community of S. alterniflora being 8.7 and 2.3 times as that in the native and mixed communities, respectively. S. alterniflora invasion increased significantly methanogens number, methane production potential, methanotrophs number, methane oxidation potential, plant biomass, soil organic carbon content and soil pH, but decreased significantly soil total nitrogen content. The correlation analysis showed that the CH4 flux was positively related to methanogens number, methane production potential, methanotrophs number, methane oxidation potential, plant biomass and soil pH, but negatively related to soil total nitrogen content. Overall, our results suggested that S. alterniflora invasion improved plant biomass production and soil pH, resulting in the increases in methanogens number and methane production potential to further drive soil CH4 emission.