Abstract:Spartina alterniflora is a rhizomatous perennial, native to the Atlantic and Gulf coasts of North America. It was introduced to China to stabilize shorelines and increase vegetative cover in 1979; and now it flourishes in many inter-tidal zones of gulfs and the estuaries in East China. Dense growth of Spartina alterniflora reduces open mud feeding habitats of shore birds, and vigorously competes with native salt mash vegetation in extended areas in South China. Salinity and temperature are two important ecological factors which affect the distribution of S.alterniflora. To find out how cordgrass adapts to the environmental conditions in the introduced range,. we studied the dynamics of a series of important physiological components including superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), malondialdehyde (MDA), soluble sugar and free proline under different salinity and temperature stress. The results showed that low NaCl concentration (lower than 100 mmol•L-1) enhanced the growth of S. alterniflora. On the contrary, high NaCl concentration (higher than 100 mmol•L-1) inhibited the growth of S. alterniflora. To a certain extent, S. alterniflora was able to acclimate to the osmotic pressure created by external solution concentration by adjusting the activities of POD, SOD, CAT, as well as the content of free proline, soluble sugar. S. alterniflora varied in its responses to environment in different parts of the plant under 5℃ and 38℃ temperature stress. Compared to roots, leaves accumulated more soluble sugar; and CAT activities in leaves were higher, whereas SOD, POD activities in leaves were much lower than that in roots.