Abstract: Through the development of alluvial islands at the mouth of Yangtze River(Chongming, Hengsha, Changxing and Jiuduansha) up till now, living and nonliving environmental factors are playing important roles. Among them the age and the height of the islands, soil types, nutrient, salinity, pH, etc. make influence on the formation, colonization and succession of the plant communities. On the basis of field working for several years, applying arithmetic series ordering according to time, the essay expounded the diversity of plant communities, recorded and predicted the plant amount of the past years on alluvial islands. It analyzed the succession status quo of plant communities under various habitats and the environmental factors accustomized by using Canonical correspondence Analysis (CCA), it also made biomass and habitat analysis on the competitions among isolated communities according to the investigation data of plant quadrats. All of these investigation results give basic information to understand the ecosystem on alluvial islands at the mouth of Yangtze River.

Key words: the mouth of Yangtze River, alluvial island, succession of plant community, environmental factor