Ant communities as indicators of environmental health. Successional analysis in a rehabilitation context.

Ant (Hymenoptera: Formicidae) communities were sampled with pitfall traps in four different habitats inside and near a rehabilitated lignite mining district in Tuscany (Italy). The four habitats were: (i) open fields, (ii) a middle-age mixed plantation (10 years), (iii) an old-age mixed plantation (20 years) and (iv) an oak woodland not directly affected by mining activities. The aims of the study were a) to assess the suitability of Mediterranean ant assemblages as indicators in biomonitoring of rehabilitation operations, b) to identify different stages of colonization by ant species and their relation to vegetational succession, c) to assess the degree of restoration success. Species richness and diversity indexes were not significantly different among the four environments. However, multivariate analyses showed that the communities in the different habitats were clearly segregated: similarity relationships reflected a successional gradient among rehabilitated sites and showed a clear gap between them and the woodland sites. The analyses of ant assemblages provided information on the effects of rehabilitation practices and some insights into community dynamics along an ideal successional gradient.