Biological triggering waste rock-based soil system with native plant litter establishes soil microbiome and biochemical functional potential typical of Eucalyptus woodland

Soil microbiomes native to Eucalyptus woodlands are critical to decomposing low-quality litter, characterized by high lignin content and wide carbon: nitrogen ratios (~60:1), supporting sustainable nutrient cycling in nutrient-poor forest soils. This study evaluated the effectiveness of native litter inoculation as a field-based strategy to establish key microbial groups in eco-engineered soils constructed from non-hazardous gravel waste rocks, aimed at facilitating Eucalyptus woodland restoration. Inoculation of native litter significantly increased microbial diversity and reshaped community composition in surface soils, enriching core taxa shared with adjacent native woodlands. Following inoculation, microbial communities exhibited increased abundance of C- and N-cycling taxa, including ammonia-oxidizing archaea (Nitrososphaeraceae) and diverse organic matter decomposers (Bacteroidetes, Ascomycota), alongside a decline in stress-adapted groups such as thermophilic Thermoplasmata and Glomeromycota. Network analyses revealed increased archaeal and bacterial modularity and enhanced fungal connectivity and clustering, reflecting improved resource partitioning and cooperative interactions potential. These microbial shifts coincided with the biological triggering of soil organic matter decomposition and enhanced N cycling during the wet season. The results demonstrate that native litter inoculation is a practical, low-input approach to accelerate microbial functional recovery in waste rock-based soils, providing a mechanistic basis for its integration into field-based Eucalyptus woodland rehabilitation.