Plant diversity and species composition of the abandoned mines of the Iglesiente mining district (Sardinia, Italy): A restoration perspective

Abstract

The ‘metalliferous ring’ of Iglesiente was for centuries the most important mining district of Italy. After a marked decline in mining activities, alternative management strategies were proposed to face issues mainly related to unemployment and environmental pollution. We focused on the coastal section of the mining district, in order to evaluate the development of vegetation after disturbance and assess the conservation value of the study area. The floristic composition in terms of species richness, number of endemics, evenness, life form diversity, vegetation and cryptogamic covers were analysed for 96 vegetation samples. Three main plant assemblages with 227 vascular plant species and 18 endemics were described. The most influential variable in determining species composition was the herbivory, which negatively affects species richness, endemic species richness and life form diversity and, positively, the evenness. Other influential variables were elevation, positively associated with species and endemic species richness, and the degree of debris/rock flow, which negatively influences species richness and life form diversity. Soil grain size positively influences evenness and negatively life form diversity and vegetation cover. The number of years of mining inactivity was only positively influencing life form diversity. Each identified community, especially those characterised by perennial herbs and small shrubs, can provide surrogate habitats for many endemic plants, which can be in turn used for phytostabilization and remediation. Further indications for strategic management of these mining environments, where policy and long-term monitoring are necessary interrelated strategies, were provided.