关键词: 牦牛, 放牧强度, 高寒草甸, 节肢动物, 生物多样性

Abstract: 【Aim】 Climate change and overgrazing are seriously threatening the functions of alpine meadows on the Qinghai-Tibetan Plateau, southwestern China. Theoretically, large herbivore grazing is tightly related to the boveground arthropod diversity, while this relationship remains unclear. 【Methods】 Yak (Bos grunniens), as a typical native livestock on the Qinghai-Tibetan Plateau, was used as animals to conduct grazing experiment in alpine meadows. Four grazing intensities (heavy grazing: 3 yaks/hm²; moderate grazing: 2 yaks/hm²; light grazing: 1 yak/hm2; and no-grazing) were set and metabarcoding technology combined with traditional plant quadrat survey was used to examine the effects of grazing intensity on the α diversity (Simpson, Chao1, ACE, and Shannon-Wiener), relative abundance and β diversity of aboveground arthropods, the α diversity (Shannon-Wiener diversity index, species richness and Pielou’s evenness index) of plant communities, and the relationships between the α diversity of aboveground arthropods and the α diversity of plant communities. 【Results】 The results showed that the α diversity of aboveground arthropods in alpine meadows did not differ significantly among different grazing intensities, while moderate grazing tended to increase the arthropod diversity. The dominant order of aboveground arthropods under different grazing intensities was the Orthoptera, with the relative abundance of 97.30%, 81.93%, 94.29% and 67.60%, respectively, under no-grazing, light grazing, moderate grazing and heavy grazing. Grazing increased the relative abundance of the Hemiptera and Diptera. The community structures of aboveground arthropods under no-grazing and moderate grazing showed slight difference, but those under light grazing and heavy grazing obviously differed. There was no significant correlation between aboveground arthropod diversity and plant community diversity. 【Conclusion】 This study suggest that yak grazing intensity has no significant effect on aboveground arthropod diversity in alpine meadows, but obviously alters the relative abundance of the dominant species and community structures of aboveground arthropods. Moderate grazing might be the optimal grazing intensity to protect aboveground arthropod diversity. This study, to a certain extent, provides theoretical supports for the maintenance and protection of biodiversity in alpine meadows.

Key words: Bos grunniens, grazing intensity, alpine meadow, arthropod, biodiversity