Abstract: The no-grazing practice in the regreening period is an effective measure to conserve the ecological environment of grassland. This study focused on the effects of no-grazing practice at the regreening period on the nutritional quality and ecological stoichiometric characteristics of carbon,nitrogen and phosphorus of plant community in the alpine meadow with an aim to analyze the feasibility of no-grazing measures. In this study,a field control experiments were conducted on typical alpine meadows in the sourceland of Three Great Rivers in a regreening period (early May to late June) with the treatments as grazing (CK) and the four consecutive no-grazings for 20 d,30 d,40 d and 50 d respectively. The nutrient quality,carbon,nitrogen and phosphorus contents of the plant community were measured in the peak of that growth season (mid-August). The results showed that the crude protein (CP) of the plant community increased significantly in all no-grazing treatments,with a most increment of 25.7% in 30 d no-grazing treatment. The total organic carbon (TOC),total phosphorus (TP) and C:N of the plant community were the highest in the 50 d no-grazing treatment. TOC and TP increased by 116.26 g·kg^-1 and 2.04 g·kg^-1 respectively compared to the control of the grazing treatment. The N:P and C:P of plant community were the highest in the no-grazing for 20 days suspension. The grazing suspension rate was positively correlated with TOC,TN,TP and C:N ratio,and negatively with C:P and N:P ratios. Therefore,the nutrient content of the alpine meadow plant community can be improved effectively by resting grazing in the greening period.

Key words: No-grazing time, Nutritional quality, C,N,P stoichiometry characteristics, Alpine meadow

摘要： 为研究返青期休牧对高寒草甸植物营养品质和碳氮磷特性的影响,本研究对三江源区典型高寒草甸进行了不同返青休牧期的野外控制试验。在返青期(5月初-6月末)设置了放牧(CK)和4个休牧期(20 d,30 d,40 d和50 d)的处理,在牧草生长旺季(8月中旬)测定了植物群落的营养品质和碳(Carbon,C)氮(Nitrogen,N)磷(Phosphorus,P)化学计量比。结果表明:与放牧处理相比植物群落的粗蛋白含量在休牧30 d处理下显著增加了25.7%;而植物群落总有机碳、全磷含量以及C:N比值在休牧50 d最高,总有机碳和全磷含量较对照分别增加了116.26 g·kg^-1和2.04 g·kg^-1。植物群落N:P比值和C:P比值在休牧20 d最高;休牧率与植物群落总有机碳、全氮、全磷含量以及C:N比值呈极显著正相关关系,与C:P比值和N:P比值呈显著负相关关系。因此,返青期休牧可有效地改善高寒草甸植物群落的养分含量。

关键词: 休牧时间, 营养品质, 碳氮磷化学计量学特征, 高寒草甸