This study investigated the effects of different grazing systems on plant communities, and examined the causes of Mongolian grassland desertification. The typical steppes near the Chinese-Mongolian border were studied using quadrat sampling and remote sensing methods. Aboveground biomass in the steppe areas differed significantly among the three grazing systems (p < 0.05): Biomass in the grazing-prohibited areas (455.9 g) was greater than that in the rotational-grazing areas (268.4 g) and the continuous grazing areas (122.2 g). Aboveground biomass was well correlated with the Soil Adjusted Vegetation Index (SAVI; y = 5600x² + 260x + 110; R² = 0.67; p < 0.05). The relative mean deviation between the aboveground biomass was calculated using this regression and the measured biomass was 29.1%. The Soil Adjusted Vegetation Index (SAVI) values for nomadic-grazing areas were greater than those for continuous-grazing areas in 1989, 2005, 2011, and 2016, and were significantly greater in 2011 and 2016. The SAVI values for the continuous-grazing areas were slightly, but not significantly greater, than those for the nomadic-grazing areas in 1993. Plant species that dominated in moderately degraded areas were most dominant in nomadic-grazing areas, followed by continuous-grazing areas and grazing-prohibited areas. Plant species that dominated in lightly and heavily degraded areas were most dominant in continuous-grazing areas, followed by nomadic-grazing areas and grazing-prohibited areas. Generally, continuous grazing caused more serious grassland degradation than did nomadic grazing, and nomadic-grazing areas tolerated more intense grazing than did continuous-grazing areas.

Bayan Obo mine is so far the world’s largest rare earth mine. Critical concerns arise as (1) whether there is an accumulation of exogenous rare earth elements (REE) in the desert steppe on the periphery of the mine and (2) how the exogenous rare earth accumulation affects the soil microbial communities nearby. In this study, nine sample sites were set up according to their distance gradients from the mine. Illumina high-throughput sequencing targeting 16S rRNA genes were conducted. The results show that the accumulation of exogenous rare earth in the desert at the periphery of the Bayan Obo mine vary at distance gradients. Fortunately, no significant effects on the physicochemical properties of the soil were found. However, the composition of the soil microbial community changed significantly in response to the variation in distance gradient. Highly abundant microbial genera YC-ZSS-LKJ147, Subgroup_10, and Sphingomonas were positively correlated with REE, whereas Pseudomonas is negative correlated. Total phosphorus (TP) was attributed to 5.95% of the variation in microbial communities, followed by light rare earth elements (LREE, 5.39%). The study provides evidence for the ecological risks posed to soil ecosystems by the long-term accumulation of exogenous REE in the Bayan Obo mine.