Native arbuscular mycorrhizal fungi respond to rehabilitation in iron ore mining areas from the Eastern Brazilian Amazon

Abstract

Rehabilitation of mining areas is a relevant and current subject, in which the response of microbial communities is an important evaluation tool regarding their progress. In this context, our study had the objective of evaluating the effect of rehabilitation on the community composition and activity of arbuscular mycorrhizal fungi, and their relation with main soil properties, in three iron ore mining sites from Serra Norte of Carajás in the Eastern Brazilian Amazon. For that, non-rehabilitated, rehabilitated, and reference areas within each site were evaluated for spore density and diversity, mycorrhizal colonization, glomalin contents, as well as soil chemical and physical attributes. In general, all mycorrhizal variables responded positively to the rehabilitation processes in the three mining sites. Over time, an increase of similarity of the mycorrhizal communities between rehabilitated and reference areas from each site was observed, as well as, a decrease of the easily extractable glomalin/total extractable glomalin ratio. High ratios of easily extractable glomalin/total extractable glomalin indicated high degree of disturbance and/or disequilibrium of ecosystems, whereas low ratios indicated their equilibrium and/or recovery. This relation can be an interesting parameter, easy to interpret and compare for assessing the degree of disturbance, equilibrium and/or recovery of environments, regardless of absolute values of these variables. Main soil properties related to mycorrhizal response were pH, texture, organic matter content, and cation exchange capacity. Briefly, our results showed the resilience of native mycorrhizal communities and the success of the rehabilitation actions carried out in this Amazonian region.