Abstract: To investigate the relationship between functional traits and ecosystem functions of dominant forage grasses in alpine meadows under global change, three dominant species of alpine meadows (Kobresia humilis, Poa crymophila and Elymus nutans) were used as experimental materials. Open top chambers (OTC) were used to simulate global warming and to study the functional diversity of the dominant species and the productivity and stability of the community after warming. The results showed that moderate warming had a positive effect on the functional richness and functional divergence, but negatively affected the functional evenness of the community. Light grazing increased the functional divergence only;warming and grazing reduced the stability and aboveground biomass of the alpine meadow community. There was no obvious relationship between community stability and aboveground biomass on alpine meadows;the functional diversity of dominant species did not affect the community stability, but negatively affected the above-ground biomass, and warming does not change the influence, light grazing modulated the functional diversity of dominant species to increase aboveground productivity. In the context of continued climate change in the future, the promotion of moderate grazing is a good management practice to maintain sustainable grassland development.

Key words: Qinghai-Tibetan Plateau, Open Top Chamber, Functional diversity, Above-ground biomass, Correlation

摘要： 为探究全球变化背景下高寒草甸优势牧草的功能性状与生态系统功能的关系及变化，本研究以高寒草甸的3种优势种矮嵩草（Kobresia humilis）、冷地早熟禾（Poa crymophila）和垂穗披碱草（Elymus nutans）为试验材料，采用国际通用的开顶式生长小室（Open top chambers，OTC）的增温方法模拟全球变暖，测定增温后优势种的功能多样性指标以及群落的生产力和稳定性。结果表明：中度增温对高寒草甸群落功能丰富度和功能离散度有积极影响，但降低了功能均匀度，而轻牧只提高了功能离散度；增温和放牧均会降低高寒草甸群落稳定性和地上生产力。高寒草甸的群落稳定性与地上生产力没有显著关系；优势种的功能多样性并不影响群落稳定性，但是与群落地上生物量是负相关关系，增温没有改变这种影响方式，轻度放牧会调控优势种的功能多样性以提高地上生产力。在未来持续气候变化的背景下，适度放牧是一种保持草地可持续发展的良好管理方式。

关键词: 青藏高原, OTC, 功能多样性, 地上生物量, 相关性