Responses of soil microbial activities to soil overburden thickness in restoring a coal gangue mound in an alpine mining area

Abstract

This study analyzes the changes in soil microbial community diversity after five years of restoration in an alpine mining area using different soil overburden thicknesses, in which MiSeq high-throughput sequencing technology was applied to analyze soil microbial community diversity and its influential environmental factors. The results showed that vegetation restoration obviously changed the species composition of soil microorganisms at the OTUs (Operational Taxonomic Units) level under different soil overburden thicknesses, and the OTUs species of soil fungi and bacteria changed significantly in the 15 cm soil overburden thickness. The bacterial diversity index was higher than that of fungal microorganisms in all three soil overburden thicknesses, and the microbial diversity index without soil overburden thickness was significantly higher than that in the soil overburden thickness (P < 0.05). The dominant phyla and genera of soil bacteria and fungi were almost the same. The bacteria were Proteobacteria, Pseudoarthrobacter and Sphinomonas, and the fungi were Ascomycota and Tricharina. The relative abundance of soil bacteria and fungi varied with the soil overburden thickness. Vegetation height, coverage, moss coverage, soil temperature, moisture, organic matter, nitrogen content, pH and soil overburden thickness were the key factors affecting the soil microbial community structure. A soil overburden thickness of 10 cm was recommended as an ideal soil reconstruction measure in apline mining areas. During the restoration period of the coal gangue mound in the alpine region, significant improvement was observed in the sensitivity of soil microorganisms to thickness over the course of five years. However, in order to facilitate continuous restoration of microorganisms, it is recommended to implement measures such as covering the area with non-woven fabrics and adjusting the pH of the soil to create more favorable conditions for microbial growth.