Abstract: A field manipulation experiment was conducted to study the effects of clipping (stubbled 3 cm, stubbled 1 cm, and unclipped), fertilizing (fertilized and non-fertilized), and watering (watered and non-watered) on the compensatory height (CH), relative height growth rate (RGR), specific leaf area (SLA), net photosynthesis rate (NPR), and total aboveground biomass per ramet (TAB) of two major plant species (Kobresia humilis and Elymus nutans) in an alpine K. humilis meadow, aimed to compare the grazing-tolerance of the two species, and to analyze the relationships between the tolerance and the resource availability of soil. The CH and TAB of the two species had an under-compensatory response to clipping, while the RGR increased significantly with clipped intensity and the clipped effect was accumulative over time. The responses of SLA, NPR, and TAB to clipping were more sensitive for E. nutans than for K. humilis. Though fertilization greatly improved the test indices of the two species, the grazing-tolerance index of K. humilis under fertilized and non-fertilized conditions was smaller than that of E. nutans. Watering had little effects on the tolerance index of the two species. It was suggested that the grazing-tolerance of the two species depended on the resource availability of soil to some extent, and K. humilis had a higher tolerance ability than E. nutans.

Key words: Biomass, Net primary productivity, Artificial tropical rainforest