Grasslands contain a large global pool of soil organic carbon (C), but the carbon flux in response to grazing exclusion and the affecting factors are still under debate. In this study, a manipulative experiment was conducted in alpine meadow of the eastern Tibetan Plateau. The sites were: 9 years grazing exclusion, GE9; 5 years grazing exclusion, GE5; and free grazing, FG in degraded alpine meadow. Results showed that there had been a significant increase in soil respiration (SR) and net ecosystem exchange (NEE) with fencing duration. However, no significant difference of ecosystem respiration (ER) was found between grazing and fencing sites. Though, carbon sink occurred in all three sites during the growing season, only the site for 9 years fencing increased gross ecosystem productivity (GEP). Remarkably, temperature sensitivity (Q₁₀) of both soil and ecosystem respiration raised in GE5 but declined in GE9. These findings indicated that grazing exclusion could be a promising measure to CO₂ sequestration in alpine meadow. Of the governing factors, exponential relationships among SR, ER and soil temperature and significant relationships among NEE, GEP and plant biomass were found. Besides, our results showed that plant nitrogen (N), phosphorus (P) content exhibited significant effects on SR, NEE, respectively. While soil C and N were significant explanatory factors for ER. These results indicated that C, N, and P content of plant and soil could provide a new insight for understanding carbon flux in alpine meadow. Together, the findings are not only vital to improve understanding of C cycle in grasslands, but also to provide scientific data for assessing the ecological effect and carbon budget of grazing exclusion.

草地含有大量的全球土壤有机碳（C）库，但对放牧排斥反应的碳通量及其影响因素仍在争论中。本研究在青藏高原东部高寒草甸进行了操控实验。这些地点是：9 年放牧排斥，GE9；5 年放牧排斥，GE5；和自由放牧，退化的高寒草甸 FG。结果表明，随着围栏时间的延长，土壤呼吸（SR）和净生态系统交换（NEE）显着增加。然而，在放牧和围栏站点之间没有发现生态系统呼吸（ER）的显着差异。尽管在生长季节期间所有三个地点都发生了碳汇，但只有将生态系统总生产力 (GEP) 围栏 9 年的地点增加了。值得注意的是，温度敏感性（Q₁₀ ) 土壤和生态系统呼吸在 GE5 中增加，但在 GE9 中下降。这些发现表明，放牧排除可能是一种有希望的 CO ₂措施在高山草甸隔离。在控制因素中，发现了 SR、ER 和土壤温度之间的指数关系以及 NEE、GEP 和植物生物量之间的显着关系。此外，我们的结果表明，植物氮 (N)、磷 (P) 含量分别对 SR、NEE 有显着影响。而土壤C和N是ER的重要解释因子。这些结果表明植物和土壤的 C、N 和 P 含量可以为理解高寒草甸的碳通量提供新的见解。总之，这些发现不仅对于提高对草地碳循环的理解至关重要，而且为评估放牧排斥的生态效应和碳收支提供科学数据。