Assessing the impact of reforestation on the diversity of Mediterranean terrestrial Gastropoda

In the Mediterranean basin, pine tree reforestation has been the most common management tool in restoring degraded and burnt areas, as well as for economic purposes. However, the quality of the biodiversity of these habitats has undergone little assessment. Terrestrial gastropods are suitable indicators of forest quality and long-term stability because of their strict dependence on microhabitat conditions and their slow dispersal rate. We sampled the gastropod population in a protected Mediterranean area in order to compare the species richness in seven main habitats. Holm oak wood and mixed-pine forests were the habitats with the lowest species density, and areas with a high level of heterogeneity exhibited the richest communities. In recent decades however, land abandonment and pine reforestation are leading to landscape homogeneity, which is perhaps the cause of the extinction of six open-habitat gastropod species in the Park. These results provide park authorities with insights into how to adapt management plans to enhance habitat quality for land snail and slug assemblages. More specifically, our results stress the need to create habitat heterogeneity to increase land mollusc diversity in large and continuous areas of mixed-pine forests.