Abstract: This study selected typical grassland in Gannan alpine meadow to research the effects of seasonal grazing on plant diversity and soil physical and chemical properties. The results showed that:Compared with the fencing area,the vegetation coverage of the seasonal grazing area decreased from 90.5% to 79.1%,the vegetation height significantly decreased by 44.1%,and the density significantly decreased by 49.5% (P<0.05). Seasonal grazing reduced the quantity of high quality forage grass and increased the quantity of poisonous grass. It also reduced the amount of annual and biennial herbs and increased the distribution of semi-shrubs. Seasonal grazing increased Margalef index,Shannon-wiener index,Simpson diversity index and evenness index of alpine grassland vegetation. Compared to the fencing area,seasonal grazing significantly reduced the organic carbon content in soil by 28.3% and increased the total nitrogen content by 27.5% (P < 0.05). This study will help to accurately understand the impact of seasonal grazing on alpine grassland and provide scientific basis for grassland ecological restoration in Gannan region.

Key words: Alpine meadow, Seasonal grazing, Plant diversity, Soil physical and chemical property

摘要： 为研究季节性放牧对高寒草地植被及土壤理化性质的影响，本研究在甘南玛曲县选取典型的季节性放牧和围封样地，从植被的群落组成、物种多样性及土壤理化性质等角度来评估季节性放牧对草地健康状况的影响。结果表明：与围封样地相比，季节性放牧样地植被盖度由90.5%降至79.1%，植被高度显著降低了44.1%，密度显著降低了49.5%（P<0.05）。季节性放牧减少了优质牧草的数量，增加了毒草的数量；同样减少了一年生、两年生草本的数量，增加了半灌木的分布。季节性放牧提高了高寒草地植被的Margalef指数、Shannon-Wiener指数、Simpson多样性指数与均匀度指数。与围封相比，季节性放牧使得土壤中的有机碳含量显著降低了28.3%，而全氮含量显著升高了27.5%（P<0.05）。本研究将有助于准确认识季节性放牧对高寒草地的影响，为甘南地区草地生态修复提供科学依据。

关键词: 高寒草地, 季节性放牧, 植物群落, 土壤理化特性