Studies on plant community on the Jiuduansha Shoals at the Yangtze Estuary

The study was carried out on the Jiuduansha Shoals at the Yangtze Estuary. Jiuduansha Shoals are newly formed shoals, and comprise three parts: Shangsha, Zhongsha and Xiasha. In order to assess the plant community on the Jiuduansha shoals and put forward suggestions for environmental protection and exploiture in this area, we took the field investigations on the shoals in 2000 and 2001. The article focused on the advance vegetation community composition,structure , features, and the growth characteristics.;The research results showed:(1)The vegetation on the Jiuduansha Shoals obviously lies in the early stage of natural community succession. (2)the vegetation on the Jiuduansha Shoals is mostly clone-vegetation and the composition and structure of plant communities were relatively simple.(3)The species diversity on the Jiuduansha Shoals was low and the vegetation keeps its initial feature.(4)The vegetation on Shangsha is relatively well-developed, has distinct vegetation belts, and is consisted of 13 plant species. The dominant species are Phragmites australis and Scirpus mariqueter in the south-west and north-east respectively.(5)The dominant species on both Zhongsha and Xiasha is Scirpus mariqueter, and there are man-planted Spartina alterniflora(introduced species)and Phragmites australis (local species)communities on Zhongsha, which were about 1 km2, and were planted as an ecological engineering in 1997.(6)Introduced Spartina alterniflora and Phragmites australis communities have accelerated the process of vegetation communities succession, and the man-made interference on the Jiuduansha Shoals is comparatively deficient. ;The authors suggest that the vegetation on the Jiuduansha Shoals should be well managed, and give the available principles on protecting and developing the vegetation on the Jiuduansha Shoals.