The Approach And Mechanism Of Reconstruction Of Hydrophytic Vegetation In Water Bodies With Degeneration Of Ecosystems

Integrated remediation on structure and function for sustainable healthy aquatic-ecosystems is the good aim and the important approach of decontamination of polluted water bodies. As the important section of lake-ecosystem, hydrophytic vegetation is of the function of primary production and ecosystem. Whether enable to reconstruct plants communities and restore aquatic vegetation, and how to display their all sorts of ecological functions, which are key programs about study of decontamination and eco-remediation.The experiment was conducted in a small pond in Xianlin Campus of Nanjing Normal University in Nanjing city, where water has been seriously polluted and aquatic higher plants have died out. In such a small artificial lake, by experiments of pot-culture propagation, strong bud sowing and artificial communities inter-plantings, the main factors that influence the growth and propagation of aquatic higher plants were investigated, such as DO; pH; transparency; temperature; concentrationof nutrition and Chl-a of water and the structure and population of algae communities. The results show as following: (1) At the beginning of reconstruction of hydrophytic vegetation, some r-strategy floating plants, as pioneering species, should be vegetated to high-speed improve water transparency and to reduce concentration of nutrition for a suitable situation for submerged plants' growth. (2) The higher coverage of floating p\ants(Eichhornia crassipes) is, the stronger their killing-algae effect is and the faster improvement of water transparency is. But it is a contradiction that water DO is gradually reduced with the increasing coverage. (3) Higher concentration of nutrition may influence the growth and survival of floating plants and leave-floating plants. (4) Physical-ecological engineering (PEEN) can make plans out of control by some environmental factors. (5) The over-growing and over-propagating of aquatic higher plants is harm to the balance of ecosystem. From 2002 to 2004, eleven species aquatic vascular plants were introduced and vegetated in the enclosure of PEEN. In the end, a successful development pattern has been found to reconstruct hydrophytic vegetation in water bodies with the interference of algae-type eutrophication.