The Study Of Nitrogen Mineralizes And Microorganism Effect Mechanism On Arctic-alpine Meadow Of Qinghai-Tibet Plateau

1.The proper order of soil organic carbon in five types of grasslands is : Kobresia~swamp meadow> Dasiphoru fruticosa shrubs> Avena sativa L artificial grassland > Kobresia humilis > Kobresia humilis-deraded grassland; The soil total N is : Kobresia~swamp meadow> Dasiphoru fruticosa shrubs> Kobresia humilis > Avena sativa L artificial grassland > Kobresia humilis-deraded grassland.2. The seasonal dynamics of soil total N in different types of grasslands is similar, in the early growing season, the soil total N content increased by temperature, Maximum appear in the August, by September, October has declined.3. The average content of soil SON and ammonium were the highest in Kobresia~swamp meadow in different types of grasslands, Kobresia humilis-deraded grassland is the lowest, soil SON and ammonium content dynamic is different in different vegetation types of grasslands.4. The content of soil microbial biomass carbon compared to soil organic carbon is 1.4 %~4.8 %, soil microbial biomass N is 0.8 %~1.3 %; Soil microbial biomass C and N is layered, which 0 ~ 10 cm layer is higher than 10 ~20 cm layer. The soil microbial biomass is changing with the changing of season. Compared with different types of grasslands, the change is different;There is significant impact on the content of soil microbial biomass C and N with environmental changing, Correlation analysis showed:Soil water content, soil organic carbon and soil total N is extremely significantly positively correlated with soil microbial biomass C and N. In addition, soil microbial biomass carbon and nitrogen is also affected by soil surface pH values.Grassland degradation, human factors including fertilizer, grazing, also on their impact.5. Correlation analysis showed: there is extremely significantly positively correlated between soil organic carbon and soil total N (p<0.05); There is significantly correlated between soil SON content and soil water content ,soil total N. It was significantly related between total number of microbial physoilogical groups and soil water content, soil total nitrogen. There is a certain correlation between microbial physoilogical groups and soil temperature, but different kinds of bacteria have different relevance.