Interaction between the physicochemical characteristics of the water environment and the mangrove plant community

To investigate the interactive effects of variables related to water environment physicochemical factors on the structure and function of plant communities in Nansha coastal wetlands,the ability of vegetation to characterize water quality under multiple ecological effects and the response and distribution of vegetation under different hydrological conditions.Using the Nansha coastal wetland in Guangzhou as the study area,12 representative plant communities were selected and transient water harvesting was carried out in their groundwater,aquatic water and five water intakes and outlets.17 water quality sampling sites,including background and control sections,were set up for field investigation.One-way ANOVA was used to analyze the indexes,and the RDA ranking in the linear model was selected by DCA to sort and analyze the plant community and environmental data.Use the Membership Function to comprehensively evaluate the environmental quality of different communities;Regression Analysis was used to model the elationship between plant communities and physicochemical factors in the water environment.The results showed that:(1)There were certain differences in physical and chemical factors of water environment between different communities of mangrove forests in Nansha coastal wetlands.Through the determination of water quality at various points,the average salinity of water body was 3.71,which belonged to brackish water,and the average TRB of water body was 14 mg/L,which belonged to medium turbidity.The concentrations of DO,COD and TP in some communities were too high,and the other indexes were within the limits.The water quality of the second phase is more polluted than the water quality of the first phase.(2)From the RDA analysis of plant communities and aquatic environment factors,there were different degrees of correlation between plant community distribution,species diversity and aquatic environment factors.(3)Use the Membership Function to evaluate the ecological environment quality of mangrove forests in Nansha coastal wetlands,and form a comprehensive evaluation system by constructing 5 first-level indicators and 26 second-level indicators.In terms of comprehensive wetland indicators,the Kandelia obovata community,Aegiceras corniculatum community,Bruguiera gymnorhiza community and Pongamia pinnata community had good ecological environment quality,followed by Cerbera manghas community,Laguncularia racemosa community and Sonneratia aperatala community.The second phase Sonneratia aperatala community,the second phase Talipariti tiliaceum community,and the second phase Pongamia pinnata community are poor and poor,all of which are in the second stage of wetlands.The interaction of mangrove plant communities and aquatic environment factors plays a key role in promoting the composition,structure and function of wetland ecosystems,and is essential for understanding the mechanisms of species coexistence,biodiversity conservation and forest management.