Preliminary Study On Effect Of Submerged Macrophytes Species Richness On Artificial Mesocosm Ecosystem Functioning Under Different Nutritional Conditions

Submerged macrophytes are large aquatic plants with the whole body or most of it sinking in the underwater. They act as the main primary producer in aquatic ecosystem, which is an important constituent part. Submerged macrophytes have strong ecological functions and play important roles in freshwater and wetland ecosystem recovery; they are also used in preventing and controlling eutrophication. In this study, we compared the effects of the functioning of the artificial aquatic mesocosm due to submerged macrophytes species richness (S0、S1、S2、S3) under different nutritional conditions (LN、MN、HN), and drew the following conclusions:1) nutrient concentrations and species richness of submerged macrophytes both produce significant impacts on plant growing, LN (the lowest nutrient concentration) treats produce the lowest biomass (p<0.05, One-way ANOVA) and S3 (3 species) treats display the highest productivity (p<0.05, One-way ANOVA); 2) interactions between nutrient concentrations and species richness are significant (p<0.01, Variance Analysis-General linear model); 3) generally, sampling effects are stronger than niche complementarity, playing a leading role in this experiment; 4) competition is the main force between Hydrilla verticillata and other two species (Relative Interaction Intensity, RII>0), whereas complementarity is found between Ceratophyllum demersum and Vallisneria natans (Relative Yield, RY>1);5) the strongest interspecific competitions are displayed under HN (the highest nutrient concentration) treat (p<0.05, One-way ANOVA). These conclusions can be used to explain how submerged macrophytes come into play during controlling eutrophication. We also come up with some suggestions and strategies when restoration of submerged macrophytes is implemented and used to control eutrophication.