Cement hardening reshapes soil microbial diversity, network stability and ecological functions of industrial area

Rapid expansion of industrialization increased the area of impermeable cement layers, disrupting substance and energy exchanges between soil and atmosphere. However, the impacts of cement hardening on soil microbial community and microbiological process remain unclear. This study compared bacterial and fungal communities between cement-hardened and bare soils across five abandoned factories. The results indicated that soil cement hardening reduced exogenous nutrients input and heavy metal accumulation. Fungal alpha-diversity responded more strongly than bacterial diversity to cement hardening. Both bacterial and fungal community compositional dissimilarities shifted significantly (p < 0.05), driven mainly by species replacement processes (74.9 and 71.1%). Microbial network's size and complexity increased under cement hardening, but the fungal network stability presented by robustness was decreased. Cement hardening narrowed the niche breadth of bacterial community (3.4) compared to bare soils (4.0), accompanied by an increased proportion of specialist species (increased by 52.7%). Deterministic process became more important in shaping the microbial community assembly in hardened soils, and heterogeneous selection dominated the phylogenetic variation, particularly for fungi (96%). Functionally, cement hardening enriched bacterial taxa involved in aerobic and anaerobic respiration, but reduced bacterial xenobiotics catabolism potential and inferred fungal saprophytic functions. Path modeling showed cement hardening directly altered bacterial composition and diversity, which indirectly influenced its function. In contrast, cement hardening directly influenced fungal community composition and functional diversity while indirectly modulating community diversity and functional composition. These findings offer new sights into the effect of cement hardening on soil microbial ecosystem and facilitates the ecological management of industrial areas.