Related Research Between Evolution Of Aquatic Plants And Aquatic Ecosystems Health

Lihu Lake,as the inland lakes in Wuxi city,can improve the life quality of nearby residents positively.However,Lihu Lake' aquatic ecosystems had been severely damaged by excessive early request.To rebuild Lihu Lake blue water,the Wuxi municipal government implemented a series of ecological restoration projects since 2003.50 the evaluation system that evaluated the effect of various aquatic ecosystem restorations needed to be established urgently.As the primary producers of aquatic ecosystems,aquatic plants established a long?term relationship of mutual influence with aquatic ecosystems.The growth and development of aquatic plants not only have an active but also a negative effect on the lake aquatic ecosystems,and various environmental factors of aquatic ecosystems also affect the growth and distribution of aquatic plants.This interaction made it possible to evaluate water ecosystem health by the growth and distribution of aquatic plants.In this paper,Lihu Lake will be divided into some different areas according to different habitats.Then four plants(emergent plants,submerged plants,floating leaf plants and floating plants)within the region will be investigated.The aquatic plants and aquatic ecosystem health status before implementation of the project were compared.The implemented ecological restoration projects and the physical chemical properties change trends of water quality and the sediment in each project area after the implementation of the project were considerd.Aquatic ecosystem health of Lihu Lake was assessed with the species diversity of aquatic plants(>3),biomass(>1000g/m2)and coverage(>30%)as the healthy lake standards.The last,evolution trends of Lihu Lake aquatic plants in the next stage were predicted.Through the field measurement and analysis of experiments in different seasons of the year,conclusions were as follows:(1)The aquatic species had recovered to 25 species belonging to 25 genera in 20 families,7 kinds of submerged plants,5 kinds of floating plants,9 kinds of emergent plants and 4 kinds of floating-leaved plants in Lihu Lake.(2)Lihu Lake aquatic ecosystem health had improved after the implementation of the various ecological restoration projects,and the stability was good.But this situation was limited in lakeside areas.Aquatic plants in open water area were still not recovered.(3)The number of aquatic species(3.21 kinds/km2)had been restored to the medium level.Submerged plants which could purify water better had been restored well,and were distributed in the whole lake shore.Aquatic Shannon diversity index(2.48)showed that Lihu Lake was still in the moderately polluted stage.The water quality of moderate period and low water period was in Grade ?,and the water quality of wet period is in Grade IV.Aquatic biomass in the whole lakeside area of Lihu Lake had reached 1000g/m2 more,but aquatic plants coverage was only 10.07%,which had obvious difference from 30%for good lake.(4)The positive correlation was significant between water COD,nitrogen and phosphorus in water and aquatic sediment and aquatic indicators.At the same time,these concentrations were basically in a favorable range for the growth of aquatic plants.This indicated that the implementation of various ecological restoration projects made Lihu water and bottom sediment become healthier.The prerequisites for the further evolution of aquatic plants were provided.(5)There were mainly antipollution-type species include Potamogeton crispus,Ceratophyllum demersum,Phragmites australis,Typha angustifolia.Trapa incisa var.quadricaudata,Nymphoides peltatum and Hydrocharis dubia in the lake shore at this stage.The water health was expected to be further improved by the various repair works and the purification of restored aquatic plants in the riparian zone.The weak resistance plants could be restored,and the aquatic plants might grow from lake shore to the open water area.In sunmary,it was the infancy stage for Lihu Lake to improve the water ecological environment health.Aquatic plants in lake had been restored by a variety of repair works,conversely,the aquatic plants improved the water environment.The stable growth of restored aquatic plants was expected to prompt plants to grow from lake shore to the open water area.This would be a long process of evolution.To ensure the evolution,it was proposed to strengthen the pollutant source control measures and ecological restoration along the rivers around the lake.So various factors of water environment could be further improved,Lihu Lake could be contacted with the surrounding rivers,and Lihu water quality could be maintained sustained and stable.In addition,environmental factors that impacted submerged plants recover should be further studied.Nutrient concentrations in water at this stage were conducive to the growth of submerged plants,so it was suggested to research and analyze the impacts of water clarity,water velocity,water depth and other factors on submerged plants.