矮生嵩草对牦牛和藏羊放牧的响应机制

Response mechanisms of Kobresia humilis to grazing of yaks and Tibetan sheep

为探讨矮生嵩草(Kobresia humilis)性状在中度放牧利用下对不同家畜的响应机制,开展了牦牛和藏羊单独放牧的控制试验,这对研究中度放牧利用下高寒草地生产力和稳定性的维持具有重要的意义。本研究测定了牦牛和藏羊放牧利用下矮生嵩草形态学及生理生化方面的10个指标:单株重、株高、比叶面积、比叶重、叶片厚度、叶绿素含量、叶干物质含量及叶片碳、氮、磷含量。结果显示:1)与禁牧相比矮生嵩草部分性状对放牧家畜有显著的响应,株高、比叶重和叶片厚度显著降低(P<0.05),单株重和比叶面积显著增加(P<0.05),且在牦牛放牧和藏羊放牧之间矮生嵩草单株重亦有显著差异(P<0.05);生理生化指标在不同的放牧处理下并无显著变化。2)各性状间的相关性分析及不同性状对放牧的敏感程度表明,矮生嵩草对放牧主要以非对称性响应为主。研究结果表明:1)中度放牧促进了矮生嵩草的生长和更新,有利于该群落的稳定和生产力的维持。2)牦牛放牧和藏羊放牧对矮生嵩草的影响是趋同的,但矮生嵩草对不同的家畜类型响应尺度存在差异,依据变异系数和变异率可知放牧牦牛对矮生嵩草株高、单株重、比叶面积、比叶重和叶片厚度的影响高于放牧藏羊。综上所述:中度放牧增强了矮生嵩草的耐牧性和适应性,且基于牦牛、藏羊采食强度的不同矮生嵩草对二者的响应机制也存在一定差异。

The response mechanisms of Kobresia humilis to livestock grazing were studied in control experiments with Yak and Tibetan sheep to clarify the maintenance of productivity and stability of Alpine grassland under moderate grazing.Ten morphological,physiological,and biochemical indices of K.humilis were measured under different grazing conditions:Individual weight,plant height,specific leaf area,specific leaf weight,leaf thickness,leaf chlorophyll content,leaf dry matter content,leaf carbon content,leaf nitrogen content,and leaf phosphorus content.Compared with no grazing,some traits of K.humilis have significant response to grazing livestock,with significant decreases in plant height,specific leaf weight,and leaf thickness(P<0.05),significant increases in individual weight and specific leaf area(P<0.05),and significant differences in individual weight of K.humilis between Yak and Tibetan sheep grazing(P<0.05).Correlation analysis and sensitivity of different traits to grazing indicated an asymmetric response mechanism of K.humilis to grazing,which was the optimal growth strategy.The study conclusions are that moderate grazing can promote the growth and renewal of K.humilis,which is beneficial to the stability and productivity maintenance of the community,and that the effects of grazing on K.humilis by Yak and Tibetan sheep are similar,but the response scales of K.humilis to different livestock types differ.To sum up:Moderate grazing enhanced the grazing tolerance and adaptability of K.humilis,and based on the different feeding intensity of yaks and Tibetan sheep on K.humilis,the response mechanism of K.humilis to grazing of yaks and Tibetan sheep was also different.