To investigate the effects of grazing and topography on alpine shrub populations， in this study the effects of topography and grazing on population growth， inter-species relationships in alpine scrub in the Qilian Mountains were analyzed by using the populations of Potentilla anserina and Poa subfastigiata as the research objects， through setting up three kinds of terrain， namely， valley， shady slopes， and sunny slopes and five different distances from livestock pens for each terrain type as grazing plots. The results showed that grazing and topography jointly regulated the growth of two plant populations. The increase in grazing pressure gradient （reduced distance from the livestock pens） inhibited the vertical （plant height） and horizontal （crown width） growth of the two species， and increased the population density and vegetation cover. The valley was characterized by a balance of water and heat resources， and the two species coexisted in the highest density， with shady slope has better humidity conditions and stable water supply， which was conducive to the growth and reproduction of moisture-loving Potentilla anserina. The sunny slope had ample sunlight and suitable thermal conditions， favoring the dominance of Poa subfastigiata in their ecological niche. The topography indirectly influenced the competition of the populations by altering the heterogeneity of microhabitats， while grazing directly influenced the competition through trampling. Topography indirectly affected population competition by altering microhabitat heterogeneity， grazing directly affects population dynamics through trampling and foraging. Topography and grazing influenced the competitive landscape of moisture-loving and drought-tolerant species， thereby affecting their status in the community. This study quantified the pathways of topography and grazing on the growth and interspecific relationships of alpine shrub populations， which can provide a scientific basis for the sustainable utilization of the alpine ecological barriers.

Alpine scrub  /  Grazing  /  Topography  /  Potentilla anserina  /  Poa subfastigiata  /  Population dynamics