Characteristics Of Typical Plant Communities And Its Responses To Environmental Factors Of Costal Wetlands In The Yellow River Delta

The coastal wetland in the Yellow River Delta is a multi-functional and biodiversity rich natural ecosystem,which plays an irreplaceable role in the sustainable ecological environment.Plant community is an important component of the wetland ecosystem,its growth,development and succession are important signs of wetland development and evolution.Therefore,strengthening the research on the relationship and response of wetland plant community characteristics and environmental impact factors,the response status,are of important significance in promoting the healthy development of the wetland ecology and the sustainable development of wetland ecological environment.The ecosystem of the Yellow River Delta is unique,and is an important national wetland nature reserve in China,but the ecological environment is relatively fragile.At the same time,in the wetland ecosystem of the Yellow River Delta,all kinds of wetland plants and their communities as an important component are of great significance for its developments and evolutions.Therefore,based on the survey data of the coastal wetland vegetation in the Yellow River Delta,this study clarified the species composition,community structure,species diversity characteristics and their succession rules.Taking the Suaeda salsa community,Tamarix chinensis community and Phragmites australis community as the typical community,as well as the soil salinity environment,nutrient environment and microclimate environmental factors,the relationship between typical plant community characteristics and environmental factors and the response status have been studied.Then,through data analysis,the key environmental factors affecting plant community changes are explained,with a view to provide certain reference basis for making decisions on the ecological environment protection and ecological restoration of the region.In the study,it is found that the plant species composition in the study area is relatively simple,with 14 species of plants,belonging to 7 families and 14 genera,and the typical plant communities are S.salsa,T.chinensis and P.australis communities.In terms of species diversity,according to the comprehensive indicators,with the increase of Shannon-Wiener index,Simpson index and Margalef index,species diversity in S.salsa community,T.chinensis community and P.australis community showed a gradual increase trend,Pielou index decreases gradually,and the plant community structure in the study area is also roughly the characteristics of S.salsa to T.chinensis to P.australis.At the same time,Jaccard index and Jaccard-distance showed that there were relatively a large number of species between S.salsa community and T.chinensis community,and the species replacement rate was slow.But the species difference between T.chinensis community and P.australis community was the largest,the species similarity was the smallest,and the species replacement rate is relatively fast.This series of change trends also showed the characteristics of community succession.In the coastal wetland of the Yellow River Delta,the characteristics of plant community change and succession are roughly:from sea to land,the distribution of plant community presents the characteristics of S.salsa to T.chinensis to P.australis.In the exploration of the environmental factors that affect the changes of plant communities and the responses status,the following have been found:First,in the aspect of environmental factors of soil salt,the phenomenon of salt accumulation is significant.In the surface layer?in the horizontal dimension?,except for the strong variation of SO₄^2-in the T.chinensis community?coefficient of variation is 1.28?and TS,Mg²⁺,Cl^-in the S.salsa community?coefficient of variation is 1.10,1.83,1.23?,the variation such as K⁺,Na⁺,Ca²⁺,Mg²⁺,Cl^-,HCO₃^-are variations of medium intensity.In the vertical dimension,except for Mg²⁺in the P.australis is a weak variation?0.09?,the rest of the ions belonged to the medium variation.Secondly,in the aspect of nutrient environmental factors,from the perspective of element content,the wetland resources in this area are deficient,and the total amount of C,N,P in different communities showed certain variation characteristics.The ecological characteristics show that in the three communities,the corresponding C:N is less than 25,and N:P is less than 14,indicating that the decomposition rate of soil organic matter in this area is significantly higher than the accumulation rate and N is controlled the important factors of plant growth in this area.Third,in the aspect of microclimate environmental factors,it has been found that soil water content?WC?is an important element in microclimate environmental factors,which affects plant communities accordingly.Fourthly,using RDA to analyzed the key environmental factors,it has been found that TS,WC and AN are the main factors that affect the plant community of the coastal wetland in the Yellow River Delta,and TS is the key factor in the frist place.