Soil arthropod community responses to restoration in areas impacted by iron mining tailings deposition after Fundao dam failure

In 2015, the failure of the Fundao dam in Mariana, Brazil released similar to 43 million m(3) of iron mining tailings into the environment. Despite restoration initiatives in the following years, few studies-and most focused on revegetation-have evaluated the effectiveness of the restoration process in areas impacted by the disaster. We aimed to evaluate the responses of the arthropod community in areas impacted by iron mining tailings deposition from the Fundao dam that is in the restoration process. We defined sampling units in the riparian zone of the Gualaxo do Norte River, which is under restoration, and in a native not impacted riparian zone. We collected soil arthropods using pitfall traps and sampled environmental variables in the same sites. We used generalize least squares models (GLS) to test if the restored areas already presented values of arthropod diversity and functional group abundance similar to the reference area and to test which environmental variables are influencing arthropod diversity. We also tested how large the differences of arthropod community composition between the study areas and used the index of indicator species (IndVal) to verify which species could be used as an indicator of reference or restoration areas. The diversity of arthropods and the functional groups of detritivores and omnivores were higher in the native riparian zone. Understory density, soil density, organic matter content, and microbial biomass carbon were the environmental variables that significantly explained the diversity and species composition of arthropods. We show that restoration areas still have different soil arthropod diversity values and community composition when compared to reference areas. Evaluating the response of the arthropod community to the restoration process and long-term monitoring are essential to achieve a satisfactory result in this process and achieve a self-sustaining ecosystem.

Automated summary

This study evaluated the impact of iron mining tailings and the restoration process on the arthropod community. The results showed differences in soil arthropod diversity and community composition between the restoration areas and the reference areas. Understory density, soil density, organic matter content, and microbial biomass carbon were identified as important environmental variables influencing arthropod diversity. Evaluating the response of the arthropod community and conducting long-term monitoring are crucial for achieving satisfactory restoration outcomes and a self-sustaining ecosystem.