Eospalax baileyi is one of the most important rodents living underground in the Qinghai-Tibet Plateau. It accumulates a mound of soil on the grassland through excavation behavior, forming bare hills of different sizes with a mosaic distribution, which has some impact on the surrounding plant communities. In this study, the plant species composition and important values of biomass composition of functional groups, species diversity and community stability were quantitatively analyzed, and the convergence rule of plant community structure and stability characteristics under grazing and fencing was clarified. The results indicated that: 1) Number of plant species was very small on mounds in fenced and grazing plots, there have 17 and 11 species, respectively. Fencing was beneficial to the invasion and growth of plants on the mound. 2) The formation of the mound increased biomass (122.71 g·m–2) and the proportion of hemicryptophytes (20.77%), and decreased the proportion of geophytes (22.50%) in the surrounding plant communities, which promoted the transformation from grassland/sedge community to grass community, but had no effect on plant species diversity of the grassland community. 3) Fencing decreased the stability, while grazing increased the stability of grassland communities around mound and non-mound areas. 4) The increase in plant biomass in the mound meadow could partly compensate for the loss of biomass in the nude mound, with 35.28% and 57.93% loss in biomass in the nude mound in fencing and grazing plots, respectively.

[目的]确定丛生禾草长芒草(Stipa bungeana)和无芒隐子草(Cleistogenes songorica)的年龄结构模式,探究其株丛分蘖数和个体分蘖质量之间是否存在自疏特征,阐释其对生境的适应性机制,进而预测草原演替趋势.[方法]以黄土高原地区丛生禾草长芒草和无芒隐子草为对象,通过对其株丛数量性状(株高、冠幅直径、基茎、分蘖数、株丛质量和个体分蘖质量)、年龄结构及自疏特征进行定量分析,研究2种丛生禾草的龄级结构及自疏特征.[结果](1)2种植物株丛的高度、冠幅直径和基茎的稳定性较强,株丛质量和个体分蘖质量的稳定性较弱.(2)2种植物种群的年龄结构均为幼年个体少,成年个体储备丰富,老年个体相对较多,均属衰退型种群,且2种植物种群的稳定性较弱.(3)无芒隐子草株丛分蘖数和个体分蘖质量之间存在一定程度自疏特征,长芒草株丛分蘖数和个体分蘖质量之间不存在自疏特征.[结论]2种禾草的年龄锥呈衰退型且其自疏特征存在一定分异,是其对外界生境和长期封育适应的结果,表明研究区草原呈退化演替趋势.