Terrestrial Arthropods in the Initial Restoration Stages of Anthracite Coal Mine Spoil Heaps in Northwestern Spain: Potential Usefulness of Higher Taxa as Restoration Indicators

Abstract

An "edaphic-landscape" restoration was performed in two anthracite coal mine spoil heaps located in NW Spain as a demonstration and pilot program for the restoration of coal mine spoils. Terrestrial arthropods were used to monitor the process as an alternative to the use of secondary succession of plants or physico-chemical indicators of soils. This study analyzes the usefulness of the terrestrial arthropods at different taxonomic levels (orders of Arthropoda, families of Coleoptera, and species of Carabidae) as restoration indicators in the initial restoration stages. The terrestrial arthropods respond rapidly to restoration, and the results may be explained by short-term increase in abiotic factors resulting from the applied techniques, mainly the animal origin of the organic matter added and the biodegradable coconut geotextile. Carabidae is of relatively low value as a short-term restoration indicator at a specific level. Coleoptera provided the best information for interpreting the ecological results over the short term and had the best relationship with the cost of identification. Likewise, the results showed that the edaphic-landscape restoration leads to an abnormal arthropod assemblage in the short term because of an excessive abundance of isopods and polydesmids. No clear convergence appeared toward any of the terrestrial arthropod communities present in the grassland, scrubland, or woodland semi-natural areas, which were used as reference end point. The restoration indicator value produced by the higher taxonomic levels of the studied terrestrial arthropods may be useful and cost-effective for assessing short-term changes caused by environmental restorations performed to recover ecosystems affected by mining activities.