PRACTICE AND IMPL ICATION OF ESTABL ISHING AQUATIC VEGETATION IN LAKE YUEHU INWUHAN, CHINA

Lake Yuehu locates in Wuhan city,which is in the middle reach of the Yangtze River. It is a small(0.66 km2) and shallow hypereutrophic lake, consists of Lake Small Yuehu and Lake Large Yuehu.The water quality of the lake was worse than Class Five(a water quality standard of China).Pioneer submersed plant community dominated by Potamogeton crispus and Elodea nuttallii was established within 2-3 years by the help of biomanipulation, purification of water with floating-leaved plants and plant floating islands in the lake, purification with wetland on the bank, transplantation of submersed plants and so on. In the spring of 2005, the coverage of submersed vegetation was 45%.Transparence of the water was imp roved markedly. It was an effective way to establish p ioneer submersed plant community by transplant Potamogeton crispus and Elodea nuttallii in winter when water level was lower and its transparence was higher than other seasons of a year. In the hypereutrophic water body, low transparence was the key factor limiting to rebuild submersed vegetation.When water level was lower or transparence was higher, aquatic plants could resist pollution more. If water level could be lowered, the effort to rebuild submersed vegetation would be more successful.To rebuild and maintain the vegetation, sewage interception was necessary, and the concentrations of nutrients in the water, such as nitrogen and phosphorous,must be reduced to some extent.The newly rebuilt plant communitywas the weakest. Intensive fluctuations of some major environmental factors, such aswater level, pollution load and so on, could easily destroy the plant community.Therefore, in this period, it was necessary to keep these factors steady and to prevent outspreading of duckweed. Itwas effective to imp rove the water transparence by fish clear along with aquatic vegetation restoration.