Changes in biodiversity and ecosystem services over time in post-mining and quarry ponds

Quarry and mining ponds are often considered environments of poor quality or marginal for biodiversity conservation, as they pose a risk to human’s health and wildlife. Conversely, once abandoned, they could be recolonised naturally and provide ecosystem services (ES), by, for example, improving water quality and providing new habitats. We visited 34 quarry and 14 mining ponds in Sardinia to gather information about their general characteristics, such as time since abandonment, diversity of animals, plants, habitats, and ecosystem services, to summarise them in a Bioindex and Ecosystem Services Index (ESI). Mines were abandoned mainly in the 1960s and 1990s, and quarries in the 1980s and 1990s; none were actively restored. The presence of 524 animals, vascular plants and habitats was recorded; 18% of the 303 ES data reflected disservices. Bioindex and ESI were poorly correlated, suggesting that an intervention might be deserved for the reintroduction of key species. Both indexes increase significantly with time to disposal, confirming that ponds in quarries and mines can naturally self-recovered. ESI is higher in quarry than in mining ponds, suggesting a greater need for active restoration in the latter. Results support the debate on managing these environments from the perspective of resource and conservation optimization.