Invertebrate communities (Collembola and Acari) in soil cover treatments for mine tailings in a long-term field experiment

Assessment of mine rehabilitation strategies including soil cover treatments rely mainly on soil physico-chemical properties or plant performance indices, while much less is known about the response of biological soil properties. This field study evaluated the response of soil mesofauna (Collembola and Acari) in soil cover treatments (mainly subsoil and subsoil) on mine tailings, with or without organic amendments. The field experiment was conducted in large (1 m3 ) units rehabilitated in 2014, and mesofauna in soil cores was assessed 7 years later. The richness of Collembola and Acari as well as the density of Acari increased with organic amendments. Collembola community composition changed with the addition of soil cover and organic amendments. The density and community composition of Acari were strongly positively associated with organic carbon. The density of Euedaphic Collembola decreased, whereas Hemiedaphic and Epedaphic forms increased with soil cover. The contribution of generalist and metal-tolerant species explained the high density of Euedaphic life forms in tailings. Species-specific traits for Collembola and Acari could play an essential role in explaining the response of populations to treatments, such as affinity for C-enriched habitats, food preferences, and sensitivity to heavy metals. Overall, it is recommended to use a multiple diversity indices approach, to collect data on the density and assemblage of mesofauna species to investigate the response of mesofauna communities to soil cover treatments. Mine tailings rehabilitation strategies should focus on improving the nutrient content of soil covers, since it benefits diversity and density of soil fauna