New insights on glass industry wasteland ecosystems

Glass manufacturing operations lead to an increasing number of abandoned slag heaps contaminated with metallic trace elements (MTE). However, the relative influence of edaphic factors on the biodiversity of glasswork wastelands is still poorly understood although closely related to sustainable land management practices. Therefore, the objectives of this research were to provide new insights into glasswork wastelands through the investigation of (i) Orthoptera, diurnal Lepidoptera, plant communities, and (ii) abiotic parameters in the topsoils. To that end, biodiversity indices were computed from ecological inventories performed on the herbaceous layer. In addition, soil samples were taken from the topsoil layer (0-10 cm) to assess agronomic properties, actually (CEC-exchangeable) and potentially bioavailable MTE fractions (DTPA-extractable) and pseudo-total MTE contents. On the one hand, the studied site was able to support a substantially higher than excepted biodiversity with orthopteran assemblages similar to grasslands and a diurnal Lepidoptera diversity comparable to urban parks. We also noted a positive influence of plant richness on the diurnal Lepidoptera community structure. On the other hand, topsoil analysis revealed a severe Pb contamination (1800-3100 mg kg^-1) and a high potentially bioavailable Pb fraction (800-1300 mg kg^-1). However, CEC-exchangeable MTE concentrations were all below the analytical quantification limits. Moreover, the site was characterized by a medium soil fertility. From these results, Pb contamination does not appear to be a primary limiting factor for the establishment of these communities. We assume that glasswork wasteland ecosytems are more affected by soil fertility or land management practices. To conclude, these sites are able to provide biodiversity ecosystem services, acting as wildlife sanctuaries for Orthoptera and diurnal Lepidoptera, and strategic metals by phytoextraction in a circular economy model. Thus, wasteland management practices should consider the local-scale drivers of biodiversity in order to reach at least the zero net loss of biodiversity.