Effects of ultramafic topsoil stockpiling during mine activities on its microbial diversity and other microbiological and physicochemical characteristics

Nowadays, ecological restoration is considered the best solution for rehabilitation of mining-degraded areas, particularly when it concerns valuable ecosystems. This case in New Caledonia, a hot spot biodiversity, with 82% endemic plant species ultramafic soils. The use topsoil to restore mined areas an important practice. However, stockpiling can reduce soil fertility. We studied evolution different properties two topsoils stored 10 m height piles on order characterize possible degradations. effects storage duration, depth, and origin were analyzed, focusing mainly bacterial fungal diversity assessed after bar-coded pyrosequencing, expressed by operational taxonomic units (OTU). Microbial activity (carbon dioxyde production), arbuscular mycorrhizal fungi (AMF) spore numbers, bulk density other physicochemical characteristics also determined. soils characterized relatively high microbial 45 phyla 7 phyla. Bacterial OTU numbers did not vary significantly 12 months storage, but community structures these groups changed. AMF was reduced storage. activity, organic carbon, total nitrogen, cation exchange capacity, carbon nitrogen ratio (C/N) decreased starting from 3 9 In contrast, pH increased, extractable concentrations potentially toxic metals varied only slightly. All changes induced population structure, diversity, biotic abiotic traits may negatively affect functions create perturbations reconstructed ecosystems revegetation. It then necessary as far possible. all cases, should exceed six before its ecosystem restoration. recommended stockpiles, possible, 1 or less minimize compaction anaerobiosis.