Physio-ecological Study Of Submerged Vegetation Restoration In Hypereutrophic Lake

As the main primary producer of aquatic ecosystem, submerged vegetation is the basis of maintainance of biodiversity of aquatic ecosystem. Submerged macrophytes provide food, and other necessary conditions to build the complicated food chains, they also sustain carnivorous and detritus food chain indirectly as well, by adding ecological space, restraining suspend substance, and improving environmental factors such as the light intensity and dissolved oxygen. At present re-establish aquatic vegetation especial submerged macrophytes is the key step to restore the degeneration of aquatic ecosystem.The objectives of this study are to explore the feasibility and strategy of the restoration of submerged vegetation in pelagic area of LakeWuLi and to study the effect of environmental factors to Potamogeton malaianus ramification and to study the adaptability of submerged plants in different N/P ratios.The result of the growth Elodea nuttallii and Potamogeton crispus under different depth showed that the depth limit of population restoration of E. nuttallii and P. crispus were 2 fold of SD (Secchi depth) and 2.3 fold of SD respectively. When SD was 1.1-1.2 m in winter, the population of E. nuttallii was successfully restored at 2.5 m depth. High SD was the key factor for the restoration of submerged vegetation in Lake WuLi. TP, SD, DO and TN were significantly ameliorated by the restored vegetation. The strategy of restoration of submerged vegetation in pelagic area of Lake WuLi was suggested to restore E. nuttallii or P. crispus population in winter to maintain clear water state, and some of the biomass of E. nuttallii ox P. crispus would be harvested at next early summer and native submerged plant species would be introduced.The result of Potamogeton malaianus ramification indicated that water depth is the dominant limited factor for ramification. Wild investigation showed light was the main influential factor for ramification .In deep-water area tubers were the main seed bank.In order to filtrate the pioneer species we compared the adaptabilities of seven submerged macrophytes in different water eutrophic level.The result of the influence of different N/P ratios on submerged macrophytes showed that Myriophyllum spicatum, Ceratophyllum denier sum and Potamogeton crispus L. had wide adaptability. Potamogeton malaianus and Hydrilla verticillata adapted to middle-nitrogen and...