关键词: 高原鼠兔, 高寒草甸, 生态位宽度, 生态位重叠, 种间联结性

Abstract: Aims To investigate the effects of plateau pika (Ochotona curzoniae) disturbance on niche breadth, niche overlap, ecological response rate, and interspecific associations of dominant plant species in alpine meadows, and to provide the scientific basis for the conservation and management of alpine meadow ecosystems. Methods From July to August 2020, disturbed and undisturbed plots were established across six typical alpine meadow regions located in the south-central part of the Tibet Autonomous Region. Plant species composition, individual abundance, and distribution were recorded through field surveys and quadrat sampling methods. Levins' formula was applied to calculate species niche breadth. Pianka's index was used to determine niche overlap, while ecological response rates were computed to assess resource competition dynamics among species. Additionally, the variance ratio method combined with 2×2 contingency table chi-square tests was employed to analyze interspecific associations. Important findings The disturbance caused by plateau pikas significantly influenced the niche characteristics and interspecific associations of dominant plant species. Under disturbance conditions, broad-niche species (e.g., Kobresia pygmaea, Kobresia humilis, and Potentilla saundersiana) maintained larger niche breadths, while narrow-niche species (e.g., Lagotis crassifolia and Astragalus milingensis) exhibited significantly reduced niche breadths. Overall niche overlap values decreased under disturbance, indicating reduced competitive pressures among species. Analysis of ecological response rates revealed that species generally exhibited negative feedback mechanisms under disturbance conditions, which contributed to community stability. In contrast, positive feedback mechanisms dominated in undisturbed conditions, potentially leading to excessive expansion of certain species. Interspecific association analysis demonstrated increased positive associations and decreased negative associations under disturbance conditions, facilitating synergistic interactions and coexistence among species. Plateau pika disturbance can alter the structure and function of alpine meadow plant communities by influencing plant niche characteristics and interspecific associations, thereby promoting resource differentiation and niche differentiation among species while reducing competition intensity within the community. Therefore, moderate plateau pika disturbance may be beneficial for enhancing community stability and species diversity. In the conservation and management of alpine meadow ecosystems, it is recommended to comprehensively consider the ecological role of plateau pikas and formulate rational management strategies accordingly.

Key words: Plateau Pika, alpine meadow, niche breadth, niche overlap, interspecific association