SURVEY OF NATIVE AQUATIC VASCULAR PLANTS AND ITS POTENTIAL APPLICATION FOR RESTORATION AND RECONSTRUCTION OF AQUATIC ECOSYSTEMS IN SHANGHAI

With the rapid economical development, more and more degraded aquatic ecosystems can not be restored by themselves after they were polluted seriously. Aquatic vascular plant especially the native species, as an important component, play a significant role for implication of self-sustainable and self-circulation in aquatic ecosystems. Reconstruction and restoration of aquatic plants and vegetations is vital to construct the artificial waterscape and recovery the degraded territorial waters. The lists of native aquatic vascular plant that restricted to Shanghai area have been established by referring to literature, and their species composition, floristic characteristic, life form, growth form and application status in artificial aquatic ecosystems have been analyzed in this paper. The results indicated that there were 160 species of native aquatic vascular plant, belonging to 83 genera and 35 families. The species composition was complicated and more than 65% of them were mono-species genus or mono-genus family. The results of floristic geographical elements showed that the 83 genera could classify into 9 floristic distributional patterns. Tropical genera form a large fraction of the total genera with the highest proportion of 64.6%, of which pantropic genera were predominantly. The dominant type of life form was emergent plant with the highest proportion of 73.1%, while the submergent plant and floating-leaved plant accounted for 15.6% and 11.3%, respectively. There were 20 types of growth form. Graminids and herbids were the main growth form type, accounted for 40% and 28.8%, respectively. Based on the ecological characteristic and functional status of common species, 20 types of growth form were classified into 6 groups, lemnids- hydrocharids group, vallisnerids-isoetids group, potamids-myriophyllids group, utricularids-certophyllids group, trapids-nymphoids group, graminids-herbids group. All of these demonstrated that there were abundant native aquatic vascular plants in Shanghai area. However, there were much mistake in the application of aquatic vascular plant and the restoration of aquatic vegetation. Aquatic vascular plant especially the native species were rarely used in artificial waterscape and degraded aquatic ecosystems. Only 68.8% of artificial waterscapes were planted with aquatic vascular plants and 79.2% of them had less than 2 species. Furthermore, more than 50% of aquatic vascular plant planted in the artificial waterscape was alien species. These alien plants could result in biological invasion and endanger to the health of ecosystem. In order to get an immediate effect, the emergent plant was applied universally while the submergent plant which has strong purification ability was sparse. Therefore, we suggested that the reproduction and cultivation of native aquatic vascular plants should been widely develop for rebuilding aquatic vegetation. Communities adapted to native habitats should also been promoted by using native species. Besides, according to the different level of water eutrophication and substrate conditions, the emergent- floating- submerged' complex community and wetland plant- aquatic plant' complex ecosystems should been reconstructed with diverse growth form plants. At the deepen area, the aquatic vegetation also should been reconstructed by the technique of ecological floating island' and ecological submerged island'. In conclusion, the artificial waterscape and degraded territorial waters should been developed into a livable aquatic ecosystem by mean of approx-nature restoration methods.