Land subsidence caused by underground coal mining resource development alters soil properties and disrupts bacterial community assembly mechanisms in wheat fields: A case study of mining ages of 16, 31, and 40 years

Underground coal mining induced subsidence alters soil properties, causing nutrient loss and reduced fertility. Soil microbial communities, which are highly sensitive to environmental changes, play a crucial role in nutrient cycling within these ecosystems. However, the dynamics of microbial succession, community assembly, and species coexistence in subsidence-affected wheat fields remain underexplored. To address this knowledge gap, this study employs 16S rRNA gene sequencing, alongside linear mixed-effects models, neutral models, and phylogenetic null models, to investigate bacterial community characteristics and assembly mechanisms in wheat fields soils at varying depths (0–20, 20–40 and 40–60 cm) near subsided lakes (within 100 m) with varying mining ages (16, 31 and 40 years). The results indicate that land subsidence increases soil moisture and alters the distribution of potassium, nitrogen, phosphorus. This process significantly (P < 0.001) enhances the similarity of bacterial communities between the middle and deep layers while emphasizing their differences from the surface layer. Over time, the long-term dynamics of conditionality rare or abundant taxa (CRAT) in the bacterial community emphasized the enhanced ability of the bacterial community to oxidise ammonia, promote the rise of soil organic matter content and improve soil aggregate stability. At greater depths, the communities show advantages in nitrification, denitrification, and the efficient utilization of limited and complex organic substrates. Additionally, with increasing depth, deterministic processes significantly influence bacterial community composition (especially CRAT), making the co-occurrence network more dependent on a few core taxa, a trend that becomes more evident as mining age increases. In contrast, communities shaped by long-term environmental fluctuations are mainly driven by stochastic processes, further confirming that increased soil moisture due to land subsidence enhances the potential for taxa dispersal. This study highlights the necessity of land reclamation and sustainable agricultural management to restore soil ecology in subsidence-affected areas.