Effects of water level fluctuations on lakeshore vegetation of three subtropical floodplain lakes, China

Vegetation communities in floodplain lakes are adapted to natural water regimes. Construction of sluices or dams between rivers and their floodplain lakes will inevitably lead to great changes in plant communities. In order to evaluate the effects of water level fluctuations (WLFs) on lakeshore vegetation in floodplain lakes of the Yangtze River, a field investigation was conducted in two river-disconnected lakes (Wuchang Lake and Shengjin Lake) and one river-connected lake (Shimen Lake). The results showed that plant species richness was highest in the disconnected Shengjin Lake with intermediate amplitude of WLFs, and lowest in the connected Shimen Lake. Species composition differed among the three lakes and the two disconnected lakes with more similar WLFs exhibiting the greatest similarity. Six plant communities were classified using TWINSPAN. Multivariate analyses showed that the amplitude of WLFs was the most important factor in determining the distribution of lakeshore plants, followed by relative elevation and duration of submergence. Our results provide an eco-hydrological basis for plant restoration in the Yangtze floodplain lakes. We suggest that fluctuating amplitude should be increased in lakes with small WLFs, and small habitats with various hydrological regimes should be created in lakes with large WLFs.