中文摘要：

以不同放牧方式下那曲高寒草甸为研究对象,通过比较土壤化学性质和土壤磷脂脂肪酸（PLFA）研究土壤微生物群落结构的变化.结果表明：土壤化学性质（总有机碳、全磷和硝态氮含量）和微生物生物量碳总体表现为休牧7年〉自由放牧〉禁牧;除真菌细菌比外,土壤PLFA总值、细菌PLFA值、真菌PLFA值、革兰氏阴性菌和革兰氏阳性菌PLFA值均表现为休牧7年〉禁牧5年〉自由放牧〉禁牧7和9年.主成分分析（PCA）表明：第1主成分（PC1=74.6%）主要由单烯脂肪酸、多烯脂肪酸、支链饱和脂肪酸组成;第2主成分（PC2=13.2%）主要由直链脂肪酸和部分单烯脂肪酸组成.土壤微生物生物量碳（MBC）和PLFA总值之间有较好的相关性.与禁牧方式相比,休牧最适宜于那曲高寒草甸健康稳定,轻度放牧也有利于高寒草甸的稳定.

英文摘要：

To clarify the effects of grazing styles on the soil microbial community in the alpine meadow, we explored the changes of soil microbial community structure in the alpine meadow loca- ted in Naqu district of Tibet Autonomous Region by analyzing the soil chemical properties and phospholipid fatty acids （PLFAs）. The results showed that the contents of soil total organic carbon, total phosphate and nitrate nitrogen under the different grazing styles followed the trend of 7-year rest grazing 〉 free grazing 〉 grazing prohibition. Except for the ratio of fungal PLFAs/bacterial PLFAs, total PLFAs, the bacterial PLFAs, the fungal PLFAs, the gram negative bacterial and the gram positive bacterial PLFAs over the different grazing types were in the order of 7-year rest grazing 〉 5-year grazing prohibition 〉 7-year and 9-year grazing prohibition. The principal component analysis （PCA） presented that the first principal component （PC1 =74.6%） was mainly composed of monounsaturated fatty acids, polyunsaturated fatty acids and branched fatty acids, and the second principal component （PC2= 13.2%） was mainly composed of saturated fatty acids and some monounsaturated fatty acids. Total PLFAs content was significantly positively correlated with microbial biomass carbon content. Compared with grazing prohibition, fallow grazing was best for the alpine meadow in Naqu district, and free grazing with light intensity was good for the alpine meadow.