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.