The Relationship Between Plant Community Characteristics And Soil Factors In The Wetland Of The Middle Reaches Of Heihe River

Wetlands are a unique ecosystem formed by the interaction of water and land,and have the function of maintaining different plant community types,and greatly promote species richness of the region.Wetland ecosystems were destroyed by natural and human factors,which seriously threaten regional ecological security.As an important part of the ecosystem,plant and soil play an important role in maintaining the health of the whole ecosystem.The plant-soil interaction mechanism has become one of the major issues affecting the sustainable development of wetlands.Wetlands in the middle reaches of Heihe River have unique ecological functions and are affected by special geographical environment.Therefore,the study of the relationship between plant community characteristics and soil in the wetland of the middle reaches of Heihe River is conducive to better protect and restore the health and sustainable development of the wetland ecosystem in the middle reaches of Heihe River,and is of great significance for maintaining the regional ecological balance and ensuring the healthy development of human beings.Based on field sampling data and soil experimental data,the floristic composition,geographical elements and life-form characteristics of wetlands in the middle reaches of Heihe River were analyzed by using botanical and phytogeographic methods.The plant community types were determined by quantitative ecology method.On this basis,the species diversity characteristics and soil characteristics of each plant communities were analyzed.Multivariate analysis approach was used to identify the relationship between plant community types,species diversity and soil factors in this area,and a plant-soil relationship model was established on the basis to seek a method to rapidly monitor the soil environmental conditions through the observation of plant.The main research contents and results are as follows:(1)A total of 30 families,71 genera and 102 plant species in the 87 sampling plots of the middle reaches of the Heihe River.The species of Gramineae,Compositae and Chenopodiaceae were dominant,accounting for 41.18% of the total species.On the whole,the plant composition of the wetland in the middle reaches of Heihe River was single and its structure was simple.The geographic elements of the flora were relatively simple.There were five types at family level and the cosmopolitan species had an absolute advantage.The genus level includes 8 types and 2 subtypes.The wetland plants in the middle reaches of the Heihe River showed temperate properties.In terms of lifestyle,perennial herbs were the main species.(2)The 87 sample plots in the study area were divided into 13 plant community types.The species diversity indices of each plant community types were relatively low,the Margalef richness index(R)ranged from 0.49 to 2.20,the Shannon-Wiener diversity index(H)varied from 0.82 to 2.21 and the Pielou evenness index(J)fluctuated from 0.66 to 0.92.Soil physical and chemical properties had differences among each plant community types.(3)Plant community species diversity in the middle reaches of Heihe River wetland was positively correlated with soil pH and water content,and negatively correlated with soil available nitrogen,available phosphorus and available potassium content.Margalef richness index(R)was positively correlated with soil pH and total phosphorus,Shannon-Wiener diversity index(H)was positively correlated with soil pH and water content,and Pielou evenness index(J)was positively correlated with soil water content and salinity.Margalef richness index(R),Shannon-Wiener diversity index(H)and Pielou evenness index(J)were negatively correlated with soil available nitrogen,available phosphorus and available potassium.(4)The plant-soil relationship model can effectively monitor the changes of soil salinity and pH.If an expansion of Calamagrostis spp.is detected,a decrease in soil salinity could be inferred.The transformation of the Inula japonica to Equisetum ramosissimum would be unfavoured and indicated an increase in soil pH.If the expansion of Tamarix spp.is detected,an increase in soil salinity and pH could be inferred.Our results supported the role of plant as soil bioindicator of disturbances and the use of plant-soil relationships model to improve the environmental management of wetland ecosystems in arid areas.