The Invasion of Spartina alterniflora Alters Carbon Dynamics in China's Yancheng Natural Reserve

Ecosystem processes are tightly linked to the structure and functioning of plant communities. Large‐scale invasion of Spartina alterniflora on unvegetated intertidal mudflats is expected to reduce atmospheric CO2 through an increase in the carbon storage of coastal ecosystem. In China's Yancheng Natural Reserve, plant carbon storage (PCS), soil total organic carbon storage (SCS), as well as CO2 and CH4 fluxes, were compared between Spartina invaded marsh and adjacent native marshes. PCS of Spartina marsh was 16.9 and 1.4 times higher compared to those of Suaeda and Phragmites marshes, whereas relatively larger aboveground PCS but smaller belowground PCS were found in the newly settled seaward margin of the Spartina marsh. SCS in Spartina marsh was also 1.5 times higher than that in unvegetated mudflat. Although Spartina vegetation assimilated a substantial amount of CO2, mass emission of CH4 from the invaded marsh was also noticed, especially in summer, it was 9–16 times higher than those from native marshes. Our study indicates that instead of CO2 being simply incorporated into PCS and SCS, carbon dynamics following Spartina invasion are more complicated. Detailed studies of CH4 emissions are needed before ascertaining whether, and to what degree, the invasion of S. alterniflora may affect the global warming process. The invasion of Spartina alterniflora on China's coastal mud flat has increased the local soil and vegetation carbon storages. However, while CO2 is fixed by the vegetation during growing seasons, the CH4 emitted of the exotic marsh during summer and autumn is extraordinary high, indicating that plant invasion may play a role in concern with the global warming process.