Local and landscape factors affecting communities of plants and diurnal Lepidoptera in black coal spoil heaps: Implications for restoration management

Post-mining sites have been repeatedly shown as crucial refuges for endangered temperate biodiversity, as they supplement vanishing non-productive and/or early successional habitats. Their effective restoration is thus a key task of applied ecology and should be based on robust evidence. Here, we present a landscape-scale study of black coal spoil heaps in the Kladno mining region, Czech Republic. Surveying vascular plants and diurnal Lepidoptera (butterflies and day-active moths), we analyzed the impact of numerous physical, local habitat, land-use, and surrounding landscape factors on the composition, species richness, and conservation value of the communities established at 11 spoil heaps. We recorded 54 species of butterflies, 37 species of moths, and 203 plant species, including 16 nationally endangered and/or regionally extinct species, which confirmed the high conservation value of postindustrial sites, even in severely industrialized regions. Several factors depending on post-mining management, topography and habitat heterogeneity were revealed as those most important for the conservation value of both plants and invertebrates communities, whereas the surrounding landscape had no effect on the communities. The species richness and the conservation value of the spoil heaps were both mainly related to the initial stages of succession and disturbances supporting these conditions, and to the heterogeneity of the habitats and the topography. On the contrary, biodiversity was suppressed when covered with fertile topsoil, as is often applied in the technical reclamation practice. Following our results, habitat heterogeneity should be created during the spoil heaping and subsequently supported by restoration management, especially by non-intensive disturbances.