Characterization of Physicochemical Properties and Microbial Communities of Tibetan Plateau Selenium-Rich Soil

The selenium-rich area of the Tibetan Plateau is located in Qinghai Province, China, at an altitude of 2200-2500 m, with selenium content exceeding 0.3 mg/kg. This study focused on the soil selenium content, physicochemical parameters, and microbial communities of selenium-rich soils in the Ping'an selenium-rich area, as part of the Tibetan Plateau. The results showed that the total selenium contents in both the Ping'an and Guide areas were significantly higher than in the control, ranging from 624.56 µg/kg to 727.48 µg/kg in Ping'an and reaching 721.74 µg/kg in Guide. Correlation analysis revealed that organic selenium content was significantly positively correlated with total phosphorus (p < 0.05), effective phosphorus (p < 0.01), and available potassium (p < 0.05) contents. Within the bacterial community, organic selenium content showed significant positive correlations with the abundance of Arthrobacter crystallopoietes (p < 0.01), Nitrosospira briensis (p < 0.01), and unclassfied Rhodobacteraceae (p < 0.01). Total selenium content was significantly negatively correlated with the abundance of Tepidisphaera mucosa (p < 0.01). RDA analysis indicated that total potassium contributed the most (30.52%), followed by total nitrogen (21.47%) and total phosphorus (15.07%). In the fungal community, organic selenium content was significantly positively correlated with the abundance of Tausonia pullulans (p < 0.01), Botryotrichum domesticum (p < 0.01), Preussia flanaganii (p < 0.05), and Enterocarpus grenotii (p < 0.01). RDA analysis showed that total phosphorus contributed the most (27.30%), followed by total potassium (21.70%) and total nitrogen (14.86%). The findings provide a scientific basis for understanding soil physicochemical properties and microbial diversity in plateau selenium-rich regions and lay a foundation for the isolation and utilization of dominant microbial species in these soils.