Abstract: With the change of habitat, there was a notable change in the Calamagrostis angustifolia community, a typical plant community in swamp wetland of Sanjiang Plain. Based on the localized observation data and field survey in typical wetland, this paper analyzed the recent thirty years evolvement trend of C. angustifolia community in the Plain. The results showed that the species frequencies of C. angustifolia community accorded with Raunkiaer frequency law, which was in the order of A＞B＞C≥D＜E. The species in C. angustifoliacommunity altered obviously, among which, shrub plants increased gradually, resulting in a reduced diversity of plant species. The abundance, div-coverageand height of C. angustifolia all presented a descending trend.

Key words: Dinoflagellate cyst, Changjiang River estuary, Red tide