Abstract: Grazing and topography are key factors influencing the structure and function of alpine shrub ecosystems， but their effects on shrub populations and communities remain unclear. For this purpose， this study explored the effects of topography （three types of slope positions） and grazing （three distances from livestock enclosure） on the dominant species of alpine shrubland Caragana jubata and the companion species Thalictrum alpinum in the Qilian Mountain Grassland Agricultural Demonstration Area. The results showed that： 1） The distance from livestock enclosure explained the plant height and height-to-crown ratio of the Caragana jubata as 45.10% and 46.80% （P<0.01）， and the plant height， height-to-crown ratio and density of the Thalictrum alpinum as 46.50%， 40.60%（P<0.01） and 55.30% （P<0.001）. The topography only affects the population coverage of the Caragana jubata， which can explain that the coverage of the Caragana jubata is 22.30% （P<0.05）. 2） The overlap degree of the ecological niches of the Caragana jubata and the Thalictrum alpinum is the lowest at a distance of 400 meters between the livestock enclosure and the highest at 1200 meters. 3） The plant height， crown breadth and density of the population of Thalictrum alpinum significantly affected the community coverage， with an interpretation rate of 35.3% （P<0.05）. The community coverage significantly affected the population density of Thalictrum alpinum， with an interpretation rate of 25.1%（P<0.01）. The plant height， density and importance value of the population of Caragana jubata significantly affected the community coverage， with an interpretation rate of 57.6%（P<0.01）. This study reveals the role of grazing and topography in influencing the shrub-herbaceous competitive balance in alpine shrublands by regulating population growth and its population-community relationship， providing a scientific basis for grazing in complex topography.

Key words: Population, Community, Height, Crown breadth, Companion species

摘要： 放牧和地形是影响高寒灌丛生态系统结构与功能的关键因素，但二者对灌丛种群及群落的作用尚不清楚。为此，本研究在祁连山草地农业示范区探究地形（3种坡位）与放牧（3个畜圈距离）对高寒灌丛优势种鬼箭锦鸡儿Caragana jubata和伴生种高山唐松草Thalictrum alpinum的影响，结果表明：（1）畜圈距离解释鬼箭锦鸡儿株高和株高冠幅比45.10%和46.80%（P<0.01），解释高山唐松草株高、株高冠幅比和密度46.50%，40.60%（P<0.01）和55.30%（P<0.001）；地形仅影响鬼箭锦鸡儿种群盖度，可解释鬼箭锦鸡儿盖度22.30%（P<0.05）；（2）鬼箭锦鸡儿和高山唐松草生态位重叠度在畜圈距离400 m时最低，1200 m时最高；（3）高山唐松草的种群的株高、冠幅和密度显著影响群落盖度，解释率为35.3%（P<0.05）；群落盖度显著影响高山唐松草种群密度，解释率为25.1%（P<0.01），鬼箭锦鸡儿种群的株高、密度和重要值显著影响群落盖度，解释率为57.6%（P<0.01）。本研究揭示了放牧和地形通过调控种群生长及其种群-群落关系，影响高寒灌丛中灌木-草本竞争平衡的作用，为复杂地形下的放牧提供科学依据。

关键词: 种群, 群落, 株高, 冠幅, 伴生种