Effects Of Grazing On Soil Microorganisms And Their Influencing Factors In Meadow Grassland Of Guizhou Province

Grassland soil microorganisms are catalysts for soil nutrient cycling and transformation.Grazing is a common and main way of grassland utilization,which can shape soil microorganisms by changing soil physical and chemical properties.In this study,we used Illumina HiSeq sequencing,variance analysis,T-test correlation analysis and redundancy analysis(RDA)to study the diversity and composition of soil bacterial and fungal communities under grazing and non-grazing conditions;diversity and composition of soil bacterial and fungal communities under grazing and non-grazing conditions;diversity and composition of soil bacterial and fungal communities affected by grazing.What are the factors? The main results are as follows:(1)Compared with non-grazing,grazing had no significant effect on chemical properties(p > 0.05),but significantly changed soil physical properties,such as grazing significantly reduced soil water content(p < 0.05),significantly increased soil pH and bulk density(p < 0.05).(2)Acidobacteria,Proteobacteria and Chloroflexi were dominant species of soil bacteria and Ascomycota,Basidiomycota and Ciliophora were dominant species of soil fungi in subtropical grassland of Guizhou,regardless of grazing or not.Compared with non-grazing,grazing increased the relative abundance of soil bacteria Chloroflexi and decreased the relative abundance of proteobacteria,increased the relative abundance of soil fungi Basidiomycota and decreased the relative abundance of Ciliophora.Beta diversity showed that compared with non-grazing,the increase of beta diversity under grazing indicated that grazing changed the structure of soil bacteria and fungi.Cluster analysis also showed that soil bacteria and fungi had corresponding distribution patterns under grazing and non-grazing conditions.RDA analysis showed that SWC was the main environmental impact factor of bacteria and fungi.Soil water content SWC positively affected bacteria and fungi under grazing,but negatively affected bacteria and fungi under grazing.Soil bulk density showed the opposite pattern.Furthermore,correlation analysis also found that soil pH,water content SWC,bulk density BD were significantly correlated with soil bacterial and fungal abundance(p < 0.05),rather than soil chemical properties.The results showed that changes in soil physical properties,rather than chemical properties,significantly changed the composition of soil bacterial and fungal communities.(3)Compared with non-grazing,the Simpson of soil bacteria and fungi showed a decreasing trend under grazing conditions,and the Simpson of soil bacteria and fungi decreased significantly.The results showed that grazing could reduce the diversity index of soil bacteria and fungi.The correlation analysis showed that SAP and SWC significantly increased the diversity of bacteria Shannon and Simpson(p < 0.05),soil bulk density BD significantly decreased the diversity of bacteria Shannon(p < 0.05),while total phosphorus content STP and available potassium content SAK significantly decreased the diversity of Shannon and Simpson(p < 0.05),indicating that the diversity of bacteria and fungi in soil was not affected in the same environment.The same factors control.Conclusion: Grazing can change the composition of soil bacterial and fungal communities and reduce their diversity.Changes in soil physical properties,rather than chemical properties,significantly altered the composition of soil bacterial and fungal communities.The diversity of soil bacteria and fungi was controlled by different soil physical and chemical properties in the same environment.