关键词: 高寒草甸, 凸起草丘, 平缓草地, 土壤含水率

Abstract: Grazing and frost heaving raised grass mounds embedded in gentle grasslands in the alpine meadow of western Sichuan plateau. In this paper,soil samples were collected along a gradient of soil moisture to analyze the differences in physicochemical properties between raised grass mounds and gentle grasslands,and compare the differences in species richness and coverage between the two habitats to determine whether raised grass mounds is a type of microhabitat that is more prone to degradation. The results showed:Soil porosity,bulk density,water content,available nutrient,total nutrient and organic matter content of the two habitats were significantly different (P<0.05). The differences in the upper layer of soil (0~10 cm) were larger than the lower layer (10~20 cm),and the degradation of upper soil was more obvious when compare to the changes of physicochemical properties of the lower layer. The soil physical properties of the two habitats were the most different under arid conditions,while the soil chemical properties are the most different under wet conditions and the soil physical properties were firstly changed during the habitat degradation process. The effect of soil water content on soil physicochemical properties,species richness and vegetation coverage was greater than habitat types. As the degree of aridification continues to increase,the species diversity of the raised grass mounds was significantly reduced,so the raised grass mounds are more susceptible to degraded microhabitat types.

Key words: Alpine meadow, Raised grass mound, Gentle grassland, Soil moisture content