Abstract: In order to reveal the response mechanism of plant functional group characteristics to long-term grazing in Stipa breviflora desert steppe,this study took Stipa Breviflora desert steppe in Siziwangqi Banner of Inner Mongolia as the research object,from May to September 2018,species composition,plant height,coverage and density of desert steppe that was enclosed for 14 years (2004-2018) under different grazing treatments were observed,and the species diversity,richness,evenness,relative abundance and important value of functional groups were analyzed. The results showed that with the increase of grazing intensity,plant species gradually decreased,and plants belonging to different functional groups disappeared in different degrees in the heavy grazing area,and plant height,coverage and productivity of different functional groups decreased;The diversity index of functional groups in the control area was significantly higher than that in the heavy grazing area,and the richness index in the control area and the light grazing area was significantly higher than that in the moderate and heavy grazing area;Diversity index and richness index of functional groups were positively correlated with productivity under different grazing treatments. It is concluded that long-term heavy grazing reduces plant diversity and richness of functional groups in desert steppe,which leads to the decrease of grassland productivity and consequently affects the sustainable utilization of grassland.

Key words: Grazing, Desert grassland, Functional groups, Productivity

摘要： 为揭示短花针茅（Stipa breviflora）荒漠草原植物功能群特征对长期放牧的响应机制，本研究以内蒙古四子王旗短花针茅荒漠草原为研究对象，2018年8月对围封14年（2004-2018）不同放牧处理下的植物物种组成、高度、盖度、密度及生产力进行观测，并对功能群植物多样性、丰富度、均匀度和重要值分析。结果表明：随着放牧强度的增加植物种类逐渐减少，在重度放牧区分属不同功能群的植物均有不同程度消失，不同功能群植物株高、盖度、生产力随放牧强度的增加均呈降低的变化趋势；对照区功能群多样性指数显著大于重度放牧区，对照区和轻度放牧区丰富度指数显著大于中度和重度放牧区；不同放牧处理下功能群多样性指数、丰富度指数与生产力呈显著正相关关系。研究认为，长期重度放牧减少了荒漠草原功能群植物多样性和丰富度从而导致草地生产力降低，进而影响草地的可持续利用。

关键词: 放牧, 荒漠草原, 功能群, 生产力