Abstract: Plant functional traits are the main indicators of plants responding to grassland changes and are of great significance for understanding the development processes of grassland. In this experiment,the leaf element content (nitrogen content，carbon content，carbon to nitrogen ratio) and population phenotypic traits (plant height，Single plant weight，leaf thickness，specific leaf area) of Stipa purpurea under mixed grazing modes (different grazing modes) of yak and Tibetan sheep were measured,aiming to clarify the influence of grazing modes on Stipa purpurea. The results showed that, different grazing modes had no significant effects on the carbon content，nitrogen content，carbon-nitrogen ratio and leaf thickness of Stipa purpurea,but had significant effects on plant height，single plant weight and specific leaf area (P<0.05). The plant height，single plant weight and specific leaf area of Stipa purpurea were most significantly affected by grazing under mixed grazing treatment of Yak and Tibetan sheep at 1∶4 (P<0.05).Compared with grazing prohibition,they were reduced by 39.0%,59.70 and 22.8% respectively;the correlation analysis showed that:plant height，specific leaf area and single plant weight were significantly positive correlated (P<0.01);single plant weight was the main trait index of Stipa purpurea in response to grazing disturbance;Comprehensive analysis showed that yak and Tibetan sheep 1∶4 mixed grazing had the most significant effect on the functional traits of Stipa purpurea.

Key words: Alpine grassland, Mixed grazing of yak and tibetan sheep, Stipa purpurea, Functional traits

摘要： 植物功能性状是植物响应草地变化的主要指标，对于了解草地发展进程具有重要意义。本试验对牦牛、藏羊混合放牧（不同放牧方式）下对紫花针茅（Stipa purpurea）叶片元素含量（碳含量、氮含量、碳氮比）及种群表型性状指标（植株高度、单株重、叶厚、比叶面积）进行测定，旨在明确放牧方式对紫花针茅的影响。结果显示：不同放牧方式对紫花针茅碳含量、氮含量、碳氮比、叶厚无显著影响，对植株高度、单株重、比叶面积影响显著（P<0.05），牦牛藏羊1∶4混牧处理下紫花针茅植株高度、单株重、比叶面积受放牧影响最显著（P<0.05），与禁牧相比，分别降低了39.0%，59.70%，22.8%；相关性分析可知：植株高度、比叶面积、单株重存在极显著正相关关系（P<0.01）；单株重是紫花针茅响应放牧干扰的主要性状指标；综合分析可得牦牛藏羊1∶4混牧处理对紫花针茅功能性状影响最为显著。

关键词: 高寒草地, 牦牛藏羊混合放牧, 紫花针茅, 功能性状