Arbuscular mycorrhizal fungi in soils of bauxite mining area under rehabilitation

Despite the fact that bauxite mining activity promotes changes in soil characteristics, with negative effects on arbuscular mycorrhizas (AM), the effects of rehabilitation on AM fungi and their symbiosis are unknown. The purpose of this study was to evaluate the occurrence, diversity and efficiency of AM fungi, in bauxite mining areas, with different vegetation types and rehabilitation ages. Rhizosphere soil samples were collected for evaluations of extraradical mycelium, spore density, richness and diversity of AM fungi and to evaluate root colonization and symbiotic efficiency of fungal populations. Mining activity had negative effects on AM fungi and the AM recovering was more related to vegetation types than to areas rehabilitation age. Six species were found: Gigaspora margarita, Gigaspora sp., Paraglomus occultum, Glomus sp., Entrophospora colombiana and Acaulospora scrobiculata. AM fungi occurrence was favored by both grasses and Mimosa scabrella. Although Eucalyptus saligna was not a good host for these fungi, its presence associated with a well developed and diverse understore contributed for the recovering of AM fungi. The fungal populations isolated from areas with Brachiaria decumbens and Cajanus cajan and from Mimosa scabrella and Melinis minutiflora were highly efficient for bean plants growth, showing that it is possible to recover the function of AM fungi using different vegetation types. These AM fungi present a high potential of utilization for the rehabilitation of mining disturbed areas.