Quantifying Sus scrofa rooting effects on the understorey of the deciduous broadleaf forests in Castelporziano Estate (Italy)

Wild boar (Sus scrofa) rooting activities may affect several taxonomic groups. In hardwood forests, wild boar’s diet is predominantly represented by plants of the ground layer. We here report a study conducted in two Mediterranean lowland forests in central Italy (the State Reserve of Castelporziano and the Circeo National Park). The aim of our study was to evaluate whether contrasting levels of rooting (high vs. low) determine different understorey species composition and diversity. Our results show that different rooting levels determine strong differences in the understorey composition. Furthermore, we found that the occurrence of different species (e.g. Ruscus aculeatus) was associated with contrasting rooting levels. Mediterranean species were significantly more frequent in plots with high levels of rooting. Plots sampled in the Castelporziano area were also characterised by species adapted to frequent disturbance and anthropogenic influence (e.g. Piptatherum miliaceum, Conyza albida); whereas species associated to low-rooting plots were typically related to deciduous forests. We found non-significant differences in diversity indices. This study demonstrates that wild boar activities cause substantial alterations in plant communities and underscores the need for long-term exclosure experiments.