The response of soil bacterial communities to mining subsidence in the west China aeolian sand area

Soil bacteria play a vital role in terrestrial ecosystems and are very sensitive to changes in the environment. Land subsidence due to underground coal mining could affect soil properties, but the extent of this effect on the soil bacterial community remains unclear. Here, we investigated the effect of land subsidence on soil bacterial communities and their response to changes in the soil environment in a control area and a land subsidence area in the West China Aeolian Sand Area. The results showed that electrical conductivity (EC), total carbon, (TC), total nitrogen (TN), available potassium (AK) and soil organic matter (SOM) at a soil depth of 20 cm were significantly decreased in the land subsidence area compared to the unexploited area, and Illumina MiSeq sequencing data revealed that the bacterial community at a soil depth of 0-180 cm was dominated by Pseudomonas, Gp4, Gp6, Sphingomonas, Gemmatimonas, Arthrobacter, Aciditerrimonas and Gaiella. Land subsidence decreased soil microbial richness and diversity. In addition, there was a significant decrease in the relative abundance of some core genera in the topsoil, such as Sphingomonas, Nocardioides and Saccharibacteria_genera_incertae_sedis, indicating that the dominant bacteria had strong anti-interference abilities and played important roles in the nutrient-poor soils of the mining area. Redundancy analysis (RDA) showed that the main factors driving the changes in the bacterial community structure were EC, water content (WC) and soil depth. The vertical leakage of water and nutrients was caused by subsidence and cracks in the ground, leading to decreased soil microbial richness and diversity. These results suggested that the soil nutrients and soil microbial community has yet to recover by self-healing after two years of land subsidence; thus, artificial restoration might be required.