Drivers of urban pollinator communities in Bologna (Northern Italy): from landscapes and plants to people

Urban areas are expanding rapidly, often at the expense of ecosystems, as impervious surfaces destroy and fragment habitats, driving biodiversity declines. Urban green spaces (UGSs), such as gardens and parks, can support pollinators by providing habitat and forage, but their effectiveness varies across cities and landscapes. Understanding these patterns at local scales is therefore essential for guiding UGS management. This thesis examines the ecological and social drivers of urban pollinators through a case study in Bologna, Italy. Across four chapters, it integrates pollinators (Chapters 1 and 2), plants (Chapter 3), and people (Chapter 4) to provide a holistic view of urban pollinator dynamics. Chapters 1 and 2 assess local and landscape-scale factors influencing hoverflies and wild bees across 15 UGSs, including urban farms and parks, using plot observations and pan traps. Pollinator abundance and richness were positively associated with local features, particularly floral richness. UGS type strongly influenced outcomes, with urban farms supporting higher pollinator diversity and abundance than parks, highlighting urban agriculture as valuable green infrastructure. Hoverflies declined with increasing surrounding urban fabric, whereas bees were more sensitive to UGS configuration, indicating contrasting responses to fragmentation. Chapter 3 investigates plant–pollinator networks to identify key plant species. Urban farms were dominated by planted ornamental, herb, and crop species attracting many pollinators, while parks relied on spontaneous forbs and grasses that provided network stability. These results informed a priority plant framework for Bologna. Chapter 4 explores public perceptions of pollinators and UGS management. Although support for biodiversity conservation was high, understanding beyond bees was limited. Communication and education emerged as effective tools for promoting pollinator-friendly practices. Overall, this thesis combines ecological and social insights to inform strategies for supporting pollinators in future urban development.