Effects of single and mixed grazing of yak and Tibetan sheep on the balance between vegetative and reproductive growth of Potentilla acaulis in alpine grassland

Grazing is the main method of grassland utilization and management. Different grazing methods have different effects on the dominant species of grassland plants. The trade-off relationship between vegetative and reproductive growth of grassland plants under different grazing conditions has scientific significance for the study of grassland vegetation restoration. This study relied on the Qinghai Tibet Plateau alpine grassland livestock system adaptive management technology platform and, under moderate grazing pressure, set up yak single grazing 1), Tibetan sheep single grazing 2), yak Tibetan sheep 1 ꞉ 2 mixed grazing, yak Tibetan sheep 1 ꞉ 4 mixed grazing, yak Tibetan sheep 1 ꞉ 6 mixed grazing, and no grazing treatments. The height, quantity, and weight of vegetative and reproductive branches of Potentilla acaulis, an indicator species of alpine grassland degradation, and the trade-off relationship between its vegetative and reproductive growth were analyzed. The results showed the following: 1) in height, number, and weight of vegetative and reproductive branches of Potentilla acaulis, the 1 ꞉ 6 mixed grazing of yak and Tibetan sheep condition yielded significantly higher values than those of other treatments, while the values for the 1 ꞉ 4 mixed grazing of yak and Tibetan sheep were generally lower than those of other treatments; 2) among the different grazing methods, the trade-off index of vegetative and reproductive branches of Potentilla acaulis was the lowest when yak and Tibetan sheep were mixed at 1 ꞉ 4; the trade-off index of yak and Tibetan sheep 1 ꞉ 6 was inclined to vegetative branches; the trade-off index of single grazing of yak, single grazing of Tibetan sheep and 1 ꞉ 2 mixed grazing of yak and Tibetan sheep favored reproductive branches; and the growth of vegetative and reproductive branches was comparable in the treatments employing no grazing, 1 ꞉ 4 mixed grazing of yak and Tibetan sheep. The results showed that in Xihai Town, Haiyan County, Haibei Prefecture, Qinghai Province, the 1 ꞉ 4 livestock combination of yak and Tibetan sheep on the alpine meadow grassland with high total coverage (more than 85%) and a simple community structure was a less healthy grazing method. This study suggests a regulation mode of grazing utilization that is conducive to the sustainable development of grassland and provides a theoretical basis for the rational utilization of alpine meadow grassland and the protection of the grassland ecological environment.