The Research Of Soil Microbial Diversity And Structure Across Different Type Grasslands In Inner Mongolia

Soil environment is highly dynamic and complex.Soil microbes become an important index in grassland ecosystem healthy evaluation for the highly sensitive to environmental change.In recent years,grassland in Inner Mongolia has been destroyed seriously.It can indicate the healthy condition of grassland ecosystem and provide theoretic reference to recover Inner Mongolia grassland and realize ecosystem service by researching spatial distribution of soil microbes,finding the relationship between soil microbes and soil physical-chemical properties and the main driving factor.This study chooses three representative grassland of Inner Mongolia-meadow grassland,typical grassland,desert grassland.We study the variation of soil microbial quantity,microbial functional diversity,community structure and its correlation with soil physical-chemical properties and found the main driving factor of bacterial community structure.The main results are as follows:(1)The date of soil culturable microbial quantity by colony-forming units indicates:bacterial number is 2.75×10~6?11.1×10~6CFU/g,actinomycete number is 6.1×10~5?2.1×10~6 CFU/g,amount of fungi is 1.8×104?1.0×10~5 CFU/g.The trend of soil microbial number is that desert grassland<typical grassland<meadow grassland.Correlation analysis finds that there is great correlation between microorganisms and soil physical-chemical properties.Numbers of bacterial,fungi and actinomycete have significant negative correlation with pH and sand content and positive correlation with other factors.Also,there is positive correlation between actinomycete number?fungi number with total nitrogen in desert grassland;bacterial number has positive correlation with soil moisture?pH and nutrient in typical grassland.Actinomycete number has significant correlation with total organic carbon?total nitrogen and silt content while fungi number has significant correlation with nutrient and mechanical composition in meadow grassland(2)The date of microbial functional features by Biolog-ECO indicates:From DS to MS,the carbon source amount and species microbe use is increasing.The range for carbon source species is from no preference to amino acid?phenols?amine?carboxylic acids as main carbon source.Richness index?dominance index?evenness index shrinks from 3.08 to 3.87,0.91 to 0.97 and 0.76-2.98.Three indexs are all express same change which meadow grassland is maximal and desert grassland is minimum.Correlation analysis indicats that richness index has significant difference with other factor except soil moisture.Dominance index has significant difference with all factors.Evenness index has significant difference with soil moisture and soil mechanical composition.Evenness index is significantly different with C/N ratio in desert grassland.Dominance index has significant difference with silt content in typical grassland;Dominance index?Evenness index have significant difference with caly content in meadow grassland.(3)The date of bacterial community structure by High-throughput sequencing indicates:The dominant species in phylum is Actinobacteria?Acidobacteria?Proteobacteria?Chloroflexi?Gemmatimonadates,these proportion are 25.8%-40.7%?13.5%-36.4%?10.9%-23.3%?9.3%-15.0%?2.7%-6.1%.Meanwhile Verrucomicrobia and Armatimonadetes have significant differences.There is great difference across different grassland in the class and order.At the same time,bacterial community structure in typical grassland is more similar to desert grassland than meadow grassland before family level.But there is opposite result after family level which means that typical grassland is desert grassland and meadow grassland transition zone.According to RDA analysis,we find soil mechanical composition is the main driving factor across three different grassland types.