Study On The Relationship Between Plant And Soil Microbial Diversity And Grassland Function In Typical Desert Plant Formation Of Junggar Basin

Desert grassland accounts for 46.9% of the total grassland area in Xinjiang.Junggar desert,as the only desert affected by the Arctic Ocean current,is different from other deserts in climate,vegetation and soil types are different.Therefore,in this study,the three representative plant formation of Junggar desert with large area distribution(Seriphidium transiliense in the southern margin,Haloxylon persicum in the hinterland and Anabasis salsa in the northern margin)were studied,and the vegetation,soil microbial and grassland productivity and carbon and nitrogen reserves of the three desert plant formation were compared by sample survey,indoor analysis and high-throughput sequencing.Spatial distribution characteristics of plant/soil microbial diversity in desert plant communities,parsing the key environmental factors affecting their distribution,and exploring the relationship between plant/soil microbial diversity and grassland function.The results cannot only enhance the understanding of the spatial variation law of Junggar desert plant/soil microbe community,but also provide important basis for understanding the structure and function of desert ecosystem and establishing reasonable management measures.The main findings are as follows:(1)The order of soil organic carbon content was as follows: S.transiliense >A.salsa >H.persicum,the total nitrogen content of soil was consistent with the change of soil organic carbon.grazing exclusion plots,the soil organic carbon and total nitrogen contents of the three desert plant formation increased and decreased,but the difference was not significant(P>0.05).and the change of soil organic carbon content and annual precipitation(60?160 mm)showed a “single peak” trend(quadratic polynomial),but a linear negative correlation with annual average temperature(4?10?).The total nitrogen content of soil showed a“single peak” relationship with the average annual precipitation and annual temperature.(2)By surveying the plant communities of three species,there were 15 species of 13 genus of 6families,including 7 species of 7 genus of 4 families of S.transiliense,7 species of 6 genera of 6 families of H.persicum,6 species of 6 genera of 2 families of A.salsa,the diversity of species was relatively small,with quinoa accounted for more than 50% of the three plant formation.the highest community height and biomass were found in the H.persicum formation,the second in the S.transiliense formation,the lowest in the A.salsa formation,the highest in the density and coverage of the S.transiliense formation,and the second in the A.salsa formation,the lowest in the H.persicum formation.community height,coverage and aboveground biomass were significantly increased in 3 desert plant formation(P<0.05),but the community density was not consistent in response to grazing in different desert plant formation.(3)There was a significant difference in the Pielou homogeneity index of the three plant formation(P<0.05),there was no significant difference in the diversity index of Simpson between the S.transiliense and A.salsa formation(P>0.05),both of them were significantly higher than those of the H.persicum formation,and the Shannon-Wiener index of S.transiliense formation was significantly higher than that of the H.persicum and the A.salsa formation(P<0.05).The Sorenson similarity index of the three desert plant groups ranged from 0.29 to 0.31 and the Jaccard index from 0.17 to 0.18.The two indexes were lower,indicating that the community similarity of the three desert plant groups was weak and the common species was less.The Simpson index of S.transiliense formation and A.salsa formation increased by 19.3% and15.8%(P<0.05),but the Simpson dominance index of H.persicum formation did not respond significantly(P>0.05);the Pielou index of the three desert plant formation did not respond significantly(P>0.05);The diversity index of S.transiliense formation,H.persicum formation and A.salsa formation Shannon-Wiener decreased significantly by 19.8%,7.7% and 21.3%(P<0.05).The Shannon-Wiener diversity index and Simpson dominance index have a “single peak” relationship between annual precipitation and annual average temperature,while the Pielou uniformity index has a linear positive correlation with precipitation and a linear negative correlation with annual temperature.(4)Actinobacteria,Proteobacteria,Chloroflexi,Acidobacteria,Gemmatimonadetes,Bacteroidetes were the six main dominant groups of bacteriaand.Ascomycota,Unidentified,Basidiomycota were the three main dominant groups of fungi in desert soil of Junggar Basin.The ? diversity of soil bacteria is classified as: S.transiliense formation >A.salsa formation >H.persicum formation;the ? diversity of soil fungi is classified as: A.salsa formation >S.transiliense formation >H.persicum formation;annual precipitation and soil organic carbon are the main environmental factors affecting the composition and diversity of bacterial communities.The most important environmental factor for community composition and diversity characteristics is soil p H.(5)There was a significant correlation between plant species diversity and grassland productivity throughout the study area(P<0.05).The relationship between soil bacterial diversity and grassland productivity was not significant(P>0.05).There were significant linear and quadratic polynomial correlations between desert plant diversity and grassland carbon and nitrogen storage(P<0.05).Soil bacterial diversity had a significant correlation with grassland carbon and nitrogen storage(P<0.05),and the correlation coefficient of soil bacterial diversity with grassland carbon and nitrogen storage is high,so soil bacterial diversity can better predict grassland carbon sequestration and nitrogen fixation function.