Response Of Soil Physical And Chemical Properties And Microbe To Different Grazing Intensities In Intemperate Typical Steppe

The typical steppe of temperate zone in Inner Mongolia is a relatively fragile ecosystem.Grazing is one of the main ways of human utilization.However,grazing will change the composition of plant community and soil properties,and then affect the health of the grassland ecosystem.Grassland soil microorganism is an important participant in soil material circulation and soil conservation in grassland.It is sensitive to environmental changes and can be used for early prediction of soil quality and fertility changes in grassland.Due to the complexity and lagging of grassland ecosystem,the changes of soil physical and chemical properties,soil microbial biomass and soil microorganism response to grazing intensity are different under grazing interference.Therefore,a comprehensive and systematic analysis of the causes of the degradation of the temperate grassland,the in-depth analysis of the correlation between the physical and biological characteristics of the soil,and the deep study of the factors that lead to the change of the soil bacteria and fungi community structure are the most important research.Based on the above background.Taking the typical steppe of temperate zone in Inner Mongolia as the research object,the change rules of soil physical and chemical properties and biological properties of grassland soil under different grazing treatments(control,mild grazing,moderate grazing and severe grazing)were analyzed by control experiments.The physical and chemical properties of soil and soil microorganism were studied by principal component analysis and partial correlation analysis.The relationship between the quality of soil and soil microbial properties,and the determination of bacteria and fungi community structure,community richness and community diversity in 0—10 cm soil layer soil by using the technique of macro genome sequencing,and the correlation of bacterial community,fungal community and environmental factors were analyzed by typical correspondence analysis and redundancy analysis.The results showed that:(1)the grazing intensity has significant influence on the soil chemical properties such as soil ammonium nitrogen,nitrate nitrogen,effective phosphorus,total nitrogen,total carbon and total organic carbon(P<0.05),the light grazing content is higher,the heavy grazing is the lowest,the physical properties of soil physical properties p H,electrical conductivity,water content and other physical properties are affected by soil depth P<0.05 significantly decreased with the increase of soil depth.(2)correlation analysis showed that soil total nitrogen and p H were significantly correlated with other environmental factors,and soil microbial biomass P was significantly positively correlated with soil nutrients(P<0.01),and soil microbial biomass nitrogen was significantly positively correlated with soil nutrients(P<0.05).(3)light grazing and moderate grazing are more beneficial to the increase of bacterial biomass,richness and diversity in soil,while severe grazing leads to the decrease of soil bacteria and the decrease of diversity.The correlation analysis showed that the relative abundance of bacteria was positively correlated with K,NH4+-N,NO3--N,AN,AP and TOC(P<0.05),and TOC,p H and K were the main environmental factors affecting the diversity of bacterial communities.(4)fungal communities were greatly influenced by grazing intensity.With the increase of grazing intensity,the number,abundance and diversity of fungi decreased.The results of redundancy analysis showed that soil fungal community richness was significantly influenced by environmental factors K,NH4+-N,AN and AP(P<0.05).