Succession of hydrophytic vegetation and swampy tendency in the East Taihu Lake.
The hydrophytic vegetation of the East Taihu Lake, China, was investigated in 1996. The areas of submerged, emerging and leaf-floating vegetation were 73.8, 45.5 and 6.7 km2, respectively. The main associations included Potamogeton maackianus, Zizania latifolia, Elodea nuttallii-P. maackianus and Phragmites communis [P. australis]. Their distribution areas constituted 39.39, 28.27, 11.20 and 6.40% of the total area of the lake. Compared with the results from an investigation performed in the lake in 1960, the variation of hydrophytic vegetation was significant in the last 40 years. The most remarkable variation was that the P. communis association in the ecotone of land and water had declined, or even disappeared. The Z. latifolia association had developed from shore to centre. Potamogeton maackianus had become dominant of submerged plants, instead of P. malaianus, Hydrilla verticillata and Vallisneria natans. The exotic species E. nuttallii, had invaded and formed a large scale association. The succession of hydrophytic vegetation indicates that the East Taihu Lake has developed a swampy tendency.