Metabolic Versatility Drives the Late-Successional Dominance of Ammonia-Oxidizing Archaea in Retreating Glacier Soils.

Climate warming accelerates glacier retreat, creating glacier forefields that serve as critical chronosequences for studying nitrogen cycling succession. Ammonia-oxidizing microorganisms (AOMs) play key roles in regulating nitrogen availability for organic carbon accumulation and plant colonization. However, the underlying metabolic mechanisms governing these successional shifts and their functional consequences for nitrification potential remain poorly understood. Here, we integrated soil physicochemical and nitrification potential measurements with a multi-omics approach (qPCR, amplicon and metagenomic sequencing) across four successional stages at the Kuoqionggangri Glacier forefield, Tibetan Plateau. Results revealed a shift from ammonia-oxidizing bacteria (AOB, primarily Nitrosospira) dominance in barren ground to ammonia-oxidizing archaea (AOA, Nitrososphaerales) dominance in meadows, driven by environmental filtering (lowered pH, increased moisture, carbon, nitrogen). Additionally, metagenomic binning showed that AOA possessed broad metabolic capacities for cycling carbon, nitrogen, sulphur and phosphorus. This metabolic versatility conferred a superior adaptive advantage, driving AOA dominance and a corresponding increase in nitrification potential. Furthermore, elevated nitrification potential was jointly driven by shifts in the AOM community and environmental variables. These findings suggest that environmental filtering and AOA metabolic versatility contribute to AOA success in late-successional soils, establishing a dual-mechanism framework for nitrification dynamics during proglacial ecosystem succession.