The Contribution of Arbuscular Mycorrhizal Fungi to Soil Enzyme Activity and the Performance of Mimosa caesalpiniaefolia in Soil Degraded by Scheelite Mining: Implications for Restoration

Mining activity severely degrades soil, increases heavy metal contamination, and hinders ecological recovery. Arbuscular mycorrhizal fungi (AMF) offer a promising strategy for restoration, but their use in Fabaceae plants, especially in mine-degraded soils, remains underexplored. This study evaluated AMF inoculation effects on soil enzymes and Mimosa caesalpiniaefolia growth in Scheelite-mining-degraded soil. In a 10-weeks greenhouse experiment, plants were grown with different AMF species ( Gigaspora margarita , Acaulospora foveata , Rhizoglomus clarum , and Mix—a combination of the three species) and without inoculation. Growth parameters, seedling quality, mycorrhizal attributes, enzymatic activity, and stoichiometry were assessed. Inoculated plants showed a greater growth compared with the control. The highest spore abundances occurred in Mix (2820), R. clarum (2261), and A. foveata (2318), with the mycorrhizal colonization highest in Mix (25.78%) and R. clarum (25.70%). The Dickson quality index was higher in R. clarum and A. foveata . The enzymatic activity varied compared with the control: β-glucosidase was higher in Mix (+62%) and A. foveata (+46%); arylsulfatase and urease increased in all AMF treatments; and acid phosphatase was highest in R. clarum (+121%). A stoichiometry and vector analysis indicated a lower P limitation in Mix and A. foveata , reflecting the trade-off between P availability and symbiotic costs. These findings highlight the biotechnological potential of AMF, particularly Mix and R. clarum , in enhancing the M. caesalpiniaefolia growth and soil enzymatic activity in mining-degraded areas.