Soil nematode communities as soil health indicators in rare earth mining areas of different restoration ages

Summary Rare earth mining activities cause severe ecological degradation, necessitating effective restoration strategies and sensitive biological indicators to assess restoration success and ecosystem health recovery. Soil nematodes, as key components of below-ground food webs, offer valuable insights into ecosystem recovery processes. This study mainly investigated soil nematode community patterns across different rare earth mining sites with varying disturbance histories and recovery stages in Meizhou city, China. We compared soil nematode communities among abandoned mining sites with less than 1 year (R1), approximately 3 years (R3) and more than 5 years of recovery (R5+), and also against an intact in situ leaching site (R0-ILS) where mining had ceased approximately 5 years ago but vegetation remained undisturbed due to less invasive extraction methods. We analysed nematode abundance, diversity, trophic structure, and ecological indices in relation to soil physicochemical properties. Results revealed a progressive recovery of nematode communities with restoration age in these mining sites, characterised by increasing abundance, genus richness and Shannon diversity. Trophic structure shifted from bacterivore-dominated communities in early restoration stages towards more balanced assemblages, with higher proportions of fungivores, omnivores and predators in older restored sites. Maturity indices increased significantly with restoration time, indicating improved food web complexity and stability. Multivariate analyses identified soil organic carbon, total N and pH as key drivers of nematode community assembly during restoration. However, even after 5+ years of restoration, nematode communities in restored surface mining sites remained distinct from the R0-ILS sites, suggesting the significant influence of mining methods on ecosystem integrity. Our findings demonstrate that nematode-based indicators could effectively track ecosystem recovery in rare earth mine restoration and highlight the importance of considering alternative, less destructive, mining approaches. This study provides valuable insights for developing targeted restoration strategies and establishing practical bioindicators for evaluating ecological recovery in degraded mining landscapes.