Responses of Arbuscular Mycorrhizal Fungi and Plant Communities to Long-Term Mining and Passive Restoration

Abstract

Mining activities cause strong soil alterations, such as heavy metal (HM) pollution, which decreases the diversity of plant communities and rhizospheric microorganisms, including arbuscular mycorrhizal (AM) fungi. The polymetallic Paramillos de Uspallata mine in the Andes Mountains, the first mining exploitation in Argentina, provides a unique scenario to study AM fungal resilience after long-term disturbance following over 40 years of inactivity. This study aimed to analyze mycorrhizal status and AM fungal communities in the mine and a nearby unexploited area and to evaluate their associations with soil parameters to elucidate life history strategies. Long-term exposure to elevated Fe, Pb, Zn, and Ag concentrations and high electrical conductivity (EC, 5.46 mS/cm) led to the dominance of Entrophospora infrequens in association with Pappostipa speciosa, demonstrating that this AM species is a stress-tolerant strategist in symbiosis with a pioneer perennial plant, resilient in the most impacted mine areas. In contrast, the unexploited area, with an EC of 0.48 mS/cm and low HM contents, supported competitive and ruderal species, revealing distinct ecological strategies of AM fungi in disturbed versus undisturbed environments. These findings highlight the potential of E. infrequens for bioremediation and ecological restoration in post-mining landscapes.