Abstract: Stipa klemenzii steppe is the main vegetation type in north piedmont of Yinshan Mountain in Inner Mongolia. It is an important ecological security barrier and animal husbandry base. Based on the primary plots data obtained from fieldworks during the growing seasons from 2012 to 2017 as well as some earlier records, we studied the community characteristics and classifications of Stipa klemenzii steppe in north piedmont of Yinshan Mountain. The results showed that the quantitative characters of the community of Stipa Klemenzii steppe had an obvious fluctuated. The average species number, height, total coverage, biomass dry weight, diversity index （Simpson and Shannon-wiener index）, average richness index and average evenness index were separately 9 species/m², 10 cm, （12±5）%, （57±33） g/m², around 0.7, 2.09 and 0.55. A total of 79 species of seed plants, belonging to 21 families and 51 genera, were obseved in Stipa Klemenzii steppe, among which the families with the most species were Gramineae, Leguminosae and Compositae. Species with the occurrence frequency exceeding 60% included Stipa Klemenzii, Convolvulus ammannii, Cleistogenes songorica, Allium tenuissimum and Astragalus galactites. As for the ecological type of water, there were 57 species of xerophytes and typical xerophytes, accounting for 72% of the total species. In addition, perennial forbs as well as annual and biennial species were the two dominant life forms, covering 48% and 24% of the species, respectively. East Palaeo-North areal-type and middle Asian areal-type were the two major floristic elements, containing 33% and 32% of the species, respectively. Based on the life forms and dominances of the species within the community, Stipa Klemenzii steppe could be classified into 3 formations, 7 association groups and 13 associations. Convolvulus ammannii and Allium polyrhizum formation were the degraded types of Stipa klemenzii. The communities with degenerated indicator species as sub dominant species and constructive species were widely distributed in north piedmont of Yinshan Mountain, reflecting that the degradation of Stipa Klemenzii steppe was still serious at present stage.

Key words: Stipa klemenzii, north piedmont of Yinshan Mountain, community characteristics, degradation