Abstract: Plant communities in the southern edge of Hulunbuir grassland were investigated from east to west over a range of 200 km. The vegetation types and biodiversity in the study area were analyzed by quantitative ecological method. A total of 98 species were recorded, dominated by species from Compositae, Leguminosae, Gramineae, and Liliaceae, together accounting for 52.58% of the total species number. Xerophytes were the main water ecotype. Perennial grasses were the main life form of plants. The results of NMDS ordination showed that the distribution pattern of vegetation was influenced by the water and heat factors, with precipitation being the most important factor. The results of similarity analysis and similarity percentage analysis showed that species composition of desert steppe community was most different from meadow steppe community. There was a significant difference between desert steppe and typical steppe. The typical steppe and meadow steppe were distributed in a mosaic structure. The meadow steppe was in a trend of transition to typical steppe. This indicated that the aggravated arid climate and unreasonable human activities led to xerophytization of all vegetation types. The results of Rényi diversity ordination of three steppe types showed that the indices of species richness, Shannon diversity and Simpson diversity were the highest in meadow steppe, followed by typical steppe and the lowest in desert steppe, while the dominance showed an opposite trend. The biodiversity of the whole study area showed a general trend of decline. The trend of simplification and xerophytization from individual to community will seriously affect the protection, exploitation, and utilization of Hulunbuir grassland.

Key words: Reclaimed mining wasteland, Soil microbial activity, Soil enzyme activity