Succession and distribution pattern of vegetation communities on Jiuduansha Wetland
九段沙湿地植被群落演替与格局变化趋势

Jiuduansha Wetland is a newly formed intertidal wetland, which consists of three parts, i.e., Shangsha, Zhongsha and Xiasha. The study on the succession and distribution pattern of vegetation communities on this wetland in 2004 showed that the dominant species were Phragmites australis, Spartina alterniflora, Scirpus mariqueter, and Scirpus triqueter. P. australis and S. alterniflora dominated the areas in high tidal flat, while S. mariquete and S. triqueter occupied the inter-middle tidal flat. The area covered by the vegetations was increased by an average of 17%, 22% and 38%-39% per year in Shangsha, Zhongsha and Xiasha, respectively, and the vegetation communities were in accelerated succession, which might be correlated with the development of the wetland. Due to artificial planting, the area covered by S. alterniflora community in Zhongsha and Xiasha increased from less than 1% in 1998 up to 22% of the whole vegetation area in 2004, and the annual increase of the total aboveground biomass of S. alterniflora was 79.79%. The competition pressure of S. alterniflora on S. mariqueter and S. triqueter was heavy. Some elementary measures on the management of the vegetation communities on Jiuduansha wetland were brought forward.