The Ulsen River,located in the Hulunbuir grassland area,connects Hulun Lake and Bell Lake,serving as an important ecological link in the area.In recent years,due to increased grazing intensity and water usage in surrounding villages,the vegetation of the Ulsen River basin has undergone a series of changes.Exploring the changes in soil microorganisms under different vegetation types in the riparian zone of the grassland area,and revealing the coupling mechanism between wetland plants,soil,and microorganisms,is of great significance for the ecological restoration of the degraded wetlands of the Ulsen River and the economic development of the grassland area.Based on field sampling surveys and the distribution characteristics of the Ulsen River plant community,this study divides the vegetation into five types: swamp(SP),degenerate swamp(DP),wet meadow(WM),swamped meadow(SPM),and salinized meadow(SAM).Using ENVI remote sensing image processing of vegetation type distribution maps,the spatial distribution pattern of wetland vegetation is displayed.High-throughput sequencing technology is used in combination with soil physical and chemical factors to explore the community structure and distribution characteristics of soil bacteria and fungi in different soil layers under different vegetation types in the Ulsen River basin,as well as their formation mechanisms.The results of the study show that:(1)The wetland vegetation in the Ulsen River basin shows a clear zonal distribution pattern.In the wetland vegetation classification map,it can be seen that salinized meadow and wet meadow are distributed on the periphery of the wetland,while swamp,degenerate swamp,and swamped meadow are distributed closer to the water surface.The Shannon-Wiener(PS)diversity index of swamp,degenerate swamp,swamped meadow,wet meadow,and salinized meadow plants decrease in sequence,with the Shannon-Wiener(PS)diversity index of swamp plants being significantly higher than that of other types,and the Shannon-Wiener(PS)diversity index of salinized meadow plants being significantly lower than that of other types.(2)The bacterial Shannon index,Ace index,and Chao1 index of the SP site are significantly higher than those of the DP,WM,SPM,and SAM sites.The bacterial Shannon index,Ace index,and Chao1 index of the SAM site are significantly lower than those of the SP,DP,WM,and SPM sites.The bacterialβ-diversity results show that the SP and DP sites are significantly separated,indicating that the microbial community of the DP site has changed after extensive grazing.The DP and WM sites have a lower degree of dispersion.The SAM and WM sites are significantly separated.The abundance of the Acidobacteria phylum is ranked from high to low as SPM(19.0%)=SAM(19.0%)>WM(17.0%)>DP(16.0%)>SP(10.0%).The lower abundance of Acidobacteria in the swamp area may be related to its better water conditions.The community differences in the SP site indicate that the bacteria are Bacteroidetes,Bacteroidia,Anaerolineales,Bacteroidales,Anaerolineaceae,etc.,and the fungi are Tremellomycetes,Cystofilobasidiales,Kriegeriales,etc.The community differences in the SAM site indicate that the bacteria are Gemmatimonadetes,Rokubacteria,Gemmatimonadetes,etc.(3)The PS,EC,TOC,and Clay have a greater impact on the structure and spatial distribution of soil bacterial communities in the 0-10 cm layer;PS,SM,N,C,EC,and C/N have a greater impact on the structure and spatial distribution of soil bacterial communities in the 10-20 cm layer;PS,SM,and p H have a greater impact on the structure and spatial distribution of soil bacterial communities in the 20-30 cm layer.The PS,EC,TOC,BD,and C have a greater impact on the structure and spatial distribution of soil fungal communities in the 0-10 cm layer;PS,p H,and EC have a greater impact on the structure and spatial distribution of soil fungal communities in the 10-20 cm layer;PS,P,and p H have a greater impact on the structure and spatial distribution of soil fungal communities in the 20-30 cm layer.The results of the structural equation model analysis show that in the swamp wetland soil,the underground biomass of plants and soil clay have a significant negative effect on fungal diversity.In the typical wet meadow site,soil clay content has a significant positive effect on bacterial diversity. |