Plant Species for Sustainable Bioretention Systems’ Implementation in Mediterranean Italian Regions: A Review

Vegetation is a key component of bioretention systems, significantly influencing their functionality and overall performance. The sustainability of these systems largely depends on the plant species’ ability to withstand the primary hydrological stresses induced by the infrastructure’s design, in combination with local climatic conditions. This study focuses on plant selection for bioretention applications in Sub-Mediterranean and Mediterranean regions of Italy, which are increasingly affected by extreme weather events, including intense rainfall, heat waves, and prolonged droughts. A review of scientific literature and stormwater management manuals developed for Mediterranean climates was conducted to evaluate both non-native species and Italian native species already used in international applications. The findings reveal a limited range of drought-tolerant non-native species in scientific literature, whereas such species are more prominently featured in California-based manuals. Moreover, among the relatively few native species identified, only a small number are truly suited to fully Mediterranean conditions, based on evaluations of Ellenberg index values. These results highlight a significant research gap, emphasizing the need for further studies, particularly focused on the target ecosystems of native flora in central and southern Italian regions.