Abstract: In order to study the effects of grazing intensities on the nutritive value of dominant species in an alpine meadow of Qilian Mountains,we selected four different grazing intensities (10 years fencing,light grazing,middle grazing and high grazing) to study their effects on the inter-annual and inter-month variations of species nutritive values. The results showed that grazing significantly increased crude protein (CP) of Kobresia humilis Sergiev and dry matter digestibility (DMD) of Caragana sinica Rehder,and significantly decreased neutral detergent fibre (NDF) of Caragana sinica Rehder (P<0.05);For four dominant species,the nutritional value showed obvious inter-annual and inter-month change,that is,the CP and DMD of dominant species were significantly higher in the wetter year than in the drier year (P<0.05),and CP and DMD were the highest in the early (June) and the lowest at the end (September) of the growing season,however,the changing trend of NDF was the opposite;The nutritive values of four dominant species were affected by grazing,inter-annual and inter-month variations and species. Therefore,it suggested that the alpine meadows fenced for 10 years should be properly grazed and transfer of grassland or supplementary feeding should be considered in dry years and at the end of forage growing season so that it could realize sustainable production of grassland and animal husbandry in alpine meadow of Qilian Mountains.

Key words: Alpine meadow, Dominant species, Grazing intensity, Nutritive value, Inter-annual and inter-month variations

摘要： 为了研究放牧强度对祁连山高寒草甸优势牧草营养价值的影响，本研究以10年围封、轻度、中度和重度放牧处理下的高寒草甸作为研究对象，研究放牧强度对4个优势种牧草营养价值年际、月际变化和种的影响。结果表明：放牧显著增加了矮生嵩草（Kobresia humilis Sergiev）的粗蛋白（CP）和锦鸡儿（Caragana sinica Rehder）的干物质消化率（DMD），显著降低了锦鸡儿的中性洗涤纤维（NDF）（P<0.05）；4种优势牧草CP和DMD表现出明显的年际和月际变化规律，即多雨年份CP和DMD显著高于干旱年份（P<0.05），6月份牧草返青季CP和DMD含量显著高于9月份牧草枯黄季（P<0.05），而NDF含量变化趋势则与之相反；4种优势牧草CP、DMD和NDF受到放牧强度、年际变化、月际变化和种的相互影响。因此，建议对围封高寒草甸进行放牧，并在干旱年份和牧草生长季末家畜转场或补饲，实现祁连山草地畜牧业的可持续发展。

关键词: 高寒草甸, 优势种, 放牧强度, 营养价值, 年际和月际变化