| The natural ecosystem of the Hexi Corridor is fragile and the soil desertification is serious,but the habitat contains abundant microbial resources.The survival and adaptation mechanism of microorganisms in desert soil and their ecosystem functions are of great significance for revealing the process of material transformation in arid areas.In this paper,16 transects were set up along the natural precipitation gradient from the southeast to the northwest of the Hexi Corridor.Through field transect setting,survey sampling,indoor soil physical and chemical property testing,and data collection and processing,the climatic characteristics(precipitation,average Air temperature,surface pressure,wind speed,evapotranspiration),vegetation community structure(number of species,height,cover,aboveground biomass),soil mechanical composition(gravel,sand,silt,clay)and soil physicochemical properties(p H,conductivity,soil moisture,alkaline nitrogen,available potassium,available phosphorus,total potassium,total nitrogen,total phosphorus,organic matter)and other factors,and one-way analysis of variance was used to explore the spatial differences in the levels of environmental factors;high-throughput Sequencing technology explores the diversity characteristics of soil bacteria and fungi;Pearson correlation analysis and redundancy analysis explore the correlation between climate characteristics,vegetation community characteristics,soil physicochemical properties and microbial community structure and diversity.The main findings and conclusions of the study are as follows:(1)The soil mechanical composition shows that the sand content of the three transects in the east of the Hexi Corridor is greater than 90%,indicating that the eastern region is dominated by sandy deserts,and the silt content of the central transect is more than 10%,indicating that The central region is a loamy desert,and the gravel content of the western transect is greater than 10%,and the silt and clay content is greater than10%,indicating that the gravel desert and loamy desert in the western region are crossdistributed.The soil p H value is between 8.39 and 9.40,indicating that the desert soil of Hexi Corridor is alkaline,and the contents of soil organic matter(SOM),total phosphorus(TP),total nitrogen(TN),and total potassium(TK)indicate that its abundance is low.or very low,the content of available phosphorus(AP)was extremely high,and the content of AP in the central region was significantly higher than that in the eastern and western regions(P<0.05).The vegetation characteristics study found that the number of dominant species of vegetation in the 16 transects of the Hexi Corridor desert was between 2 and 5,and the vegetation was scarce;the vegetation height was between 23.20 and 68.43 cm,mainly shrubs and herbs;the Margalef index indicated that the central region Species richness is higher than that of east and west,Shannon index indicates that the index of species diversity of east and middle is higher than that of west,the species of 16 transects are extremely dissimilar,and the replacement rate of plant species along the precipitation gradient changes irregularly(2)The dominant bacterial phyla in the desert soil of Hexi Corridor are Firmicutes,Proteobacteria,Actinobacteria,and Bacteroidetes.The Nanhu Township transect in Gulang County,the Hongyashan Reservoir transect in Minqin County,and the western transect are dominated by Proteobacteria,while the Huanghuatan transect in Gulang County in the east and the Qingtu Lake transect in Minqin County are dominated by Actinobacteria;For Ascomycota and Basidiomycota.The bacterial ACE index and Chao1 index of the 16 transects in the study area were significantly different(P<0.05),indicating that the bacterial richness changed significantly;the bacterial Shannon index in the eastern transect was significantly higher than that in the middle(P<0.05),and the Simpson index was the opposite.It shows that the microbial diversity in the eastern transect is higher than that in the central.The fungal ACE index and Chao1 index in the eastern part were significantly higher than those in the central transect(P<0.05),indicating that the soil fungal richness in the eastern part was significantly higher than that in the central part.In the east and west,it means that the soil microbial diversity in the central plot is higher than that in the east and west.Bacterial PCo A analysis and UPGMA Tree showed that the community structure of Huanghuatan in Gulang County and Qingtu Lake in Minqin County in the east of the Hexi Corridor was similar,the community structure of the six transects in the middle was similar,and the community structure of Nanhu Township in Gulang County and Hongyashan Reservoir in Minqin County in the east was similar to that in the west of the Hexi Corridor.The community structure of the five transects except the west transect of Guazhou county was similar,and the community structure of the west transect of Guazhou county in the west was quite different from other transects.Fungal PCo A analysis and UPGMA Tree showed that the community structure of the central transect of Hexi Corridor was similar,the community structure of Guazhou County Chengxi and Guazhou County Beijiahu transect were similar,and the community structure of other transects was similar.(3)Pearson correlation analysis showed that surface air pressure(SP)and mean air temperature(MAT)significantly affected bacterial abundance(P<0.05);wind speed(AWS),silt,clay,soil moisture(SW)Significantly affected bacterial diversity(P<0.05);altitude(ASL),precipitation(MAP),evapotranspiration(EP),SP,MAT,Gravel,Sand,Silt,Clay,SOM,available potassium(AK),available nitrogen(AN),SW significantly affected fungal richness(P<0.05);SP,MAT,Gravel,EP and Clay contents significantly affected fungal diversity(P<0.05).RDA analysis showed that: Margalef index,AWS,Clay,AP and SOM significantly affected soil bacterial community(P<0.05),and Shannon index,AWS,MAP,EP,Clay,p H,SW and TN contents significantly affected fungal community structure(P<0.05).therefore,the microbial community structure and diversity were significantly affected by environmental factors.This study shows the composition and diversity of soil microbial community structure in the Hexi Corridor desert,explains the influence of environmental factors on the distribution of microorganisms and the role of microorganisms on the development of soil ecosystems,and provides a theoretical basis for the protection of biodiversity and desert ecological services. |
