Revegetation-driven shifts in the structure and function of soil microbiomes over decadal time scales

Revegetation is a key strategy for land restoration, yet its impact on soil microbial communities and their ecological processes remains poorly understood. To address this, we applied deep metagenomic sequencing to characterise soil microbial responses following revegetation (spanning 1-31 years since planting) on grazing agricultural land in NSW, Australia. We find that revegetation drives significant shifts in soil microbiome structure, functional potential, and life history strategies, which are clearly detectable as early as three years, and persist >30 years, after revegetation. Revegetated soils were enriched in traits linked to ecosystem health including metabolic pathways involved in nutrient retention, carbon sequestration, and plant growth promotion, albeit with possible livestock-specific legacy effects. While the shifts in key biogeochemical functions occurred rapidly after revegetation, plant growth-promoting traits increased more gradually, suggesting that a native plant-adapted soil microbiome is an ongoing process that continues to develop over longer periods. Genome-resolved analyses of over 450 high-purity metagenome-assembled genomes revealed a shift in microbial life history strategies: revegetated soils favoured growth, biosynthesis, and carbon fixation strategies, whereas grazing soils selected for resource-scavenging and stress tolerance strategies. Together, our findings suggest that soil microbial communities not only respond to, but likely facilitate ecological restoration following revegetation.