Taking the eutrophic Taige canal and Caoqiao River in the upper reaches of North Taihu Lake as the experimental objects, 12 monitoring points were set up and the data were recorded. The distribution pattern of aquatic plants in the water landscape belt was studied by variance/mean ratio, aggregation intensity index, negative binomial parameter, Cassie index and α – diversity index. Based on the principle of aquatic plants repairing eutrophic water, the suitable water environment was selected. The effect of ecological restoration was studied by photometry. The results showed that: the main aquatic plant communities in this area evolved from submerged type to floating leaf type and emergent type, which showed that the vertical distribution pattern of aquatic plant communities was greatly affected by hydrology; the distribution pattern of aquatic plant diversity showed a good single hump type in the vertical direction and a single hump type in the horizontal direction; the results of ecological restoration showed that: the average removal rates of TN and TP by mixing the three plants were 86.76% and 93.89%, respectively. Among them, the best combination of TN removal was water hyacinth (Eichhornia crassipes) + lytchus (Lythrum salicaria) + calamus (Acorus calamus), and the best combination of TP removal was water hyacinth + lytchus + hibiscus (Nelumbonucifera).
The competitive relationship between aquatic plants and phytoplankton is used to transform algae water into grass water, enrich water biodiversity and restore water ecosystem.
Plants have different allelopathy effects on different algae and play an active role in regulating the succession of phytoplankton population.