Analysis of annual dynamic characteristics of submerged macrophyte community and driving factors of water environment in Xishaping Bay of Erhai Lake
Investigating the annual dynamic changes of submerged macrophyte communities and their influencing factors was helpful to understand the growth laws of aquatic plants,and it was also the basis for implementing the ecological restoration project of submerged vegetation at this stage.In this study,based on the field investigation of Xishaping Bay for nearly one year,one of the main distribution bays of submerged macrophyte in Erhai Lake,we analyzed the annual dynamic changes of submerged macrophyte communities and water environmental impact factors in the bay.The results showed that:1)The biomass of submerged macrophyte in the bay showed unimodal distribution,and Hydrilla verticillata and Ceratophyllum demersum dominated the community structure types in the upper and second half of Xishaping Bay respectively.The biomass of Ceratophyllum demersum community reached the maximum in August.Moreover,the species richness of the community decreased due to the overgrowth of Ceratophyllum demersum,and the community structure tended to be homogeneous.2)Water transparency and nutrient concentration were the main environmental factors driving the dynamic changes of community structure in the bay.From July to October,with the increase of nutrient concentration such as total phosphorus,total nitrogen and permanganate index,the transparency of lake water decreased,and the population dominance of canopy Ceratophyllum demersum increased.The submerged vegetation restoration project completed at the end of July in the bay still did not change the dominant pattern of Ceratophyllum demersum in the later period.It was suggested that the dominant species of Ceratophyllum demersum and Hydrilla verticillata should be harvested properly in summer,and the input of exogenous load should be reduced in rainy season,so as to promote the growth of bottom organisms,improve the community structure of submerged vegetation in the bay,and continuously track and evaluate the ecological benefits of submerged vegetation restoration projects.
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