Spatial distribution and succession of microbial communities in biological soil crusts as affected by microtopography factors in the granite tailing areas of Macheng, China

Microorganisms within biological soil crusts (BSCs) are crucial for in the gradual restoration of ecosystem functions in severely human-disturbed environments. However, little is known about the response of soil microbial communities to heterogeneous environments formed by microtopography in granite tailing areas. Herein, BSC samples were collected from typical microtopography (slope aspect and plant canopy) within the granite tailings area to investigate the variances in the spatial distribution of microbial communities and soil succession response to environmental variables. Results showed significant differences in the distribution of BSCs, microbial community composition, and soil properties across nine survey sites. The biomass, bacterial richness, and relative abundance of Actinobacteria, Proteobacteria, Streptophyta, and Chlorophyta of BSCs were significantly higher under the plant canopy and on shady slopes areas compared with other regions. Redundancy analysis revealed that enzyme activity had the highest explanatory power, and soil moisture content was identified as the main factor affecting for the development of BSCs. Mantel tests indicated that prokaryotic organisms were primarily affected by pH and available phosphorus, while variations in eukaryotic organisms were correlated with humic acid components, available phosphorus, and urease. In granite tailing areas, microorganisms adapted their metabolic activities based on the nutrient status of their environment. In conclusion, slope aspect and plant canopy drive changes in soil properties and nutrient structure, microbial community distribution, and BSC development. These findings offer a novel perspective on the restoration of soil ecosystems in granite tailing mining areas.