中文摘要：

研究了川西北高山草甸两个优势物种垂穗鹅冠草（Roegneria nutans）和四川嵩草（Kobresia setchwanensis）凋落物在不同放牧强度下的分解及其碳氮损失率。经过一年的分解,放牧不同程度地加速了两种凋落物的分解。垂穗鹅冠草凋落物在不放牧、轻牧、中牧和重牧草地的失重率分别为26.0、27.2、29.6和32.8%;川嵩草凋落物的失重率分别为44.0,46.2,50.4和56.2%。不放牧、轻牧、中牧和重牧草地垂穗鹅冠草凋落物碳的损失率分别为26.1%、27.5%、29.4%和32.9%,氮的损失率分别为13.6%、14.4%、17.3%和19.1%;川嵩草凋落物碳的损失率分别为41.9%、44.3%、48.5%和54.4%,氮的损失率分别为39.4%、41.4%、46.4%和52.8%。研究表明,增加的放牧强度加快了两种凋落物的分解速率,加速了凋落物中碳氮的释放;同时也表明,川嵩草凋落物的分解速率要快与垂穗鹅冠草凋落物。

英文摘要：

The decompositions of two dominant plant species litters under different grazing intensity in alpine meadow on the Northwester Sichuan were studied. The relative weight loss in the litter of Roegneria nutans is 26.0, 27.2, 29.6 and 32.8% for no grazing, light grazing, moderate grazing and heavy grazing, respectively; while 44.0, 46.2, 50.4 and 56.2% for the litter of Kobresia setchwanensis. Relative carbon loss in the litter of Roegneria nutans was 26.1%, 27.5%, 29.4% and 32.9% for no grazing, light grazing, moderate grazing and heavy grazing, respectively; while 41.9%, 44.3%, 48.5% and 54.4% for the litter of Kobresia setchwanensis; Relative nitrogen loss in the litter of Roegneria nutans was 13.6%, 14.4%, 17.3% and 19.1% for no grazing, light grazing, moderate grazing and heavy grazing, respectively; while 39.4%, 41.4%, 46.4% and 52.8% for the litter of Kobresia setchwanensis. It is concluded that increased grazing intensity tended to increase the decompositions of litters and accelerate the carbon and nitrogen cycling rates within the plant-soil system in the alpine meadow.