Slope Aspect Effects On Soil Microbial Characteristics And Ecological Stoichiometry Characteristics

The research is about the slope aspect effects on soil microbial characteristics and stoichiometry. This research selects different soil-vegetation systems for different slope aspects of gully area of Loess Plateau as study objects, analyze the physico-chemical properties and rhizosphere effects for rhizosphere and bulk soil, as well as the effects on stoichiometry, microelement, microbial, biomass and community structure character, plant’s stoichiometry and characteristic of non-structure carbohydrate in order to provide data support and theory basis for ecological restoration process mechanism and ecological effects assessment of gully area of Loess Plateau. Here is the main research results below:(1) slope aspect has great impact on soil indicators of SOC, TN, it has different impact on stoichiometric ratio. SOC and TN indicators of rhizosphere and bulk soil on shady-slope are greatly lower than other slopes, sunny-slope has a higher TN indicator for bulk soil than half-sunny slope, shady-slope has the weakest root system effect of those 2 indicators among different slopes; available soil nitrogen has gathered the nutrient in half-sunny slope; the slope has insignificant effect on C:N while it has significant effect on C:P and N:P of rhizosphere soil and bulk soil.(2)Different slope aspect has different influence on soil microelement. Apart from available Cu, those data from available Zn, Mn, Fe of rhizosphere are above non- rhizosphere in every slope aspect, which have significant rhizosphere effects. For available Fe, both rhizosphere and bulk effects show half-shady slope>shady slope>sunny slope. For available Zn,half-shady slope has the greatest data and it has significant difference from the other two. For available Mn, both rhizosphere and bulk effects have the lowest data from shady-slope while highest from sunny slope. For available Cu, rhizosphere of sunny slope is greater than shady slope. For bulk, sunny slope has the greatest data, but those two set of data don’t have a significant difference. Nutrient content is the main reason that influence the speed of the microelement distribution, the available Mn, Cu, SOC and TN show the positive correlation in rhizosphere and bulk effects while Zn has significant positive correlation with ph.(3)Slope aspect has complicated influence on soil microbial characteristics. In terms of microbial biomass, for SMBC, sunny slope ranks the first while shady slope is slightly higherthan half-sunny slope with not much contrast among those for rhizosphere soil. And for SMBC bulk effect, shady slope>half-sunny slope>sunny slope while sunny slope has the greatest SMBC rhizosphere effect. The influence to basal respiration and induced respiration have the same trend in relate to slope aspect,rhizosphere effect is highest for sunny slope and lowest for shady slope while it is the opposite for bulk. For basal respiration rhizosphere effect, sunny slope>half-sunny slope>shady slope, and the induced respiration bulk effect has a greater effect for sunny aspect than the shady one. For respiratory quotient, rhizosphere Soil,bulk Soil, the trend are all as sunny slope>half-sunny slope>shady slope. The slope has similar effect for rhizosphere micro-organisms entropy and bulkmicroorganisms entropy,which are shady aspect is much greater than the sunny aspect.In term of community Structure, bacteria content of shady slope from both rhizosphere and non- rhizosphere are much higher than the sunny slope. Sunny slope have the largest rhizosphere mycorrhizal while for bulk, shady slope has the largest content. For actinomycetes, shady slope>half-sunny slope>sunny slope for rhizosphere soil and sunny slope is significant higher than half-sunny slope for bulk soil. G-/G+ has no much difference among 3 slope aspects and rhizosphere/non- rhizosphere soil. Bacteria/fungus ratio is much higher for the half-sunny slope than the bulk. Slope aspect is one of the main motivation factor of soil microorganism.Total phosphorus and ph has greater correlation with sunny slope microbial community structure, soil organic carbon and total nitrogen has the greater correlation with microbial distribution, moisture content has the greater correlation with shady slope’s microbial community distribution.(4)Slope aspect has great influence on Plant biomass, half-sunny slope has the greatest Artemisia vestita biomass live weight, the sunny slope has the minimum underground part/above ground part biomass live weight ratio among different slope. There are huge different between carbon content of above part of Artemisia vestita and nitrogen content of underground part. Different slope aspect has different influence to C:N:P ratio of underground part and above ground part of Artemisia vestita. Among them, above ground N:P ratio and underground N:P ratio are greatly influenced by various slopes. Except for above ground soluble sugar content, slope has significant influence on soluble sugar starch and non-structured carbon content for both above ground and underground part.