Soil nitrogen (N) cycling is driven by microbial community, and these microbes can be affected by land management practices.Here we surveyed the abundance and community structure of ammonia-oxidizing arehaea (AOA), ammonia-oxidizing bacteria (AOB), nirS-and nirK-type denitrifiers under different grazing managements in Tibetan alpine meadow soil.Three treatments were compared: no grazing, seasonal grazing and continuous grazing.Real-time polymerase chain reaction (q-PCR) and PCR-clone library analysis were used.Our results showed that grazing significantly reduced aboveground vegetation biomass and total soil carbon (C), whereas increased soil nitrate concentration (NO3-).The abundance of AOA was more abundant than that of AOB with the ratio of AOA to AOB ranging from 8.3 to 31.1 and copy numbers of nirS were up to 66 to 499 higher than those ofnirK among the three treatments.Soil NO3-concentration was significantly related to AOA and nirK genes abundance, but not AOB and nirS.None of the soil environmental factors correlated with the AOB community structure, but the soil C/N ratio significantly correlated to the AOA community structure.Soil pH and C/N ratio were showed very important in structuring the nirS-type of denitrifier community, and the total soil C and NO3-were found significantly correlated to the nirK community structure.In conclusion, these results demonstrated that grazing altered the abundance and community structure of nitrifiers and denitrifers by affecting the status of soil characteristics and aboveground vegetation biomass.Different environmental factors shaped the community structure and abundance of nitrifiers and denitrifiers.AOA rather AOB played a key role in nitrification, as for denitrification, it may be determined by the combination of nirK and nirS genes.