Response mechanisms of Kobresia humilis to grazing of yaks and Tibetan sheep

The response mechanisms of Kobresia humilis to livestock grazing were studied in control experiments with Yak and Tibetan sheep to clarify the maintenance of productivity and stability of Alpine grassland under moderate grazing. Ten morphological, physiological, and biochemical indices of K. humilis were measured under different grazing conditions: Individual weight, plant height, specific leaf area, specific leaf weight, leaf thickness, leaf chlorophyll content, leaf dry matter content, leaf carbon content, leaf nitrogen content, and leaf phosphorus content. Compared with no grazing, some traits of K. humilis have significant response to grazing livestock, with significant decreases in plant height, specific leaf weight, and leaf thickness (P < 0.05), significant increases in individual weight and specific leaf area (P < 0.05), and significant differences in individual weight of K. humilis between Yak and Tibetan sheep grazing (P < 0.05). Correlation analysis and sensitivity of different traits to grazing indicated an asymmetric response mechanism of K. humilis to grazing, which was the optimal growth strategy. The study conclusions are that moderate grazing can promote the growth and renewal of K. humilis, which is beneficial to the stability and productivity maintenance of the community, and that the effects of grazing on K. humilis by Yak and Tibetan sheep are similar, but the response scales of K. humilis to different livestock types differ. To sum up: Moderate grazing enhanced the grazing tolerance and adaptability of K. humilis, and based on the different feeding intensity of yaks and Tibetan sheep on K. humilis, the response mechanism of K. humilis to grazing of yaks and Tibetan sheep was also different.