Beyond Ornament: Ecosystem Services and Disservices of Cultivated Ornamental Flora on the Circum-Sicilian Islands

Ornamental flora is often appreciated for its aesthetic and recreational value, overlooking its ecological functions. This study provides the first comprehensive assessment of ecosystem services and disservices delivered by cultivated ornamental plants across all the islands of the circum-Sicilian archipelago. We surveyed the vascular flora characterizing each island, compiling a checklist of 402 taxa. For each taxon, we recorded biological traits, beneficial services (e.g., wildlife food, human food, habitat provision, beekeeping, erosion control, green fencing, and medicinal interest), and disservices (naturalization, toxicity to humans, pets, or livestock, and allergenicity). The island of Ustica hosts the highest number of taxa (217), followed by the island of Lipari (213), while the islands of Marettimo (95) and Alicudi (96) are the poorest. Remarkably, 329 taxa are potential sources of medicine, 326 provide wildlife habitats, 299 are of beekeeping interest, 218 are suitable for living fences, 212 contribute to erosion control, 192 supply fruits for wild birds, 130 human food, and 86 livestock forage. Spatial analysis of ornamental flora reveals that the island of Favignana has the highest proportional cover (11%) with moderate clustering, the islands of Ustica and Panarea display more dispersed, larger patches, and the islands of Lipari and Salina show strongly aggregated small patches. These results demonstrate that ornamental plants perform substantial regulatory and provisioning services, and their spatial arrangement further modulates ecological outcomes.