Soil Meso- and Macrofauna Indicators of Restoration Success in Rehabilitated Mine Sites

In recent years, there has been increasing interest in developing effective rehabilitation strategies for mine waste sites. To assist industry and regulators in assessing success in restoring mine tailings, methods and indicators are needed to evaluate long-term environmental sustainability and quantify the restoration of soil functions. Understanding the pedogenesis of Technosols and ecosystem development of reclaimed mine tailings is necessary for validating rehabilitation strategies and predicting their possible risks and future trajectory. To date, the majority of studies assessing rehabilitation success have focused on surveying the vegetation structure, while few have assessed soil fauna biodiversity and its role in soil multifunctionality. Despite the large number of ecological studies that have highlighted the important role of soil fauna, especially meso- and macrofauna, in shaping ecosystem development, there is a lack of studies that evaluate the ability of reclaimed mine sites to host the necessary soil ecological communities that, in turn, deliver ecosystem functions. The functional role and response of soil fauna in these novel ecosystems have long been overlooked and understudied. Here we present the current state of the use of meso- and macrofauna in assessing mine site restoration, identifying the primary model species used, and describing the gaps in assessment that could lead to misinterpretation of restoration success. We discuss many published studies on coal mining sites: some bauxite residues and a few lignite mining sites. In contrast, much less is known about the role of soil fauna in metalliferous mine tailings. We stress the need for soil fauna indicators that can be replicated in rehabilitation assessments worldwide for metalliferous tailings.