Pollinators respond positively to urban green space enhancements using wild and ornamental flowers

Abstract

Pollinator diversity and abundance are under direct threat from human activities. Despite societal dependence on pollinators for crop production, humankind continues to drive pollinator declines through agricultural intensification and urbanisation. Urban environments can provide refuge to some pollinators. There is a need, however, to understand how pollinator communities can be supported in these areas while also considering human needs. Public green spaces provide a promising avenue to target plant–pollinator conservation measures in an urban setting due to their large area, high abundance and low plant–pollinator biodiversity. We used a paired design to compare the plant community, pollinator community and plant–pollinator interactions of (i) public urban green spaces enhanced with wildflower meadows and pollinator-friendly ornamental plantings to (ii) control unenhanced urban green spaces. The planting types within enhanced sites were also separately compared. Our results show that not only was the diversity of the overall pollinator community higher in enhanced than control sites, but also the complexity of some wild Hymenoptera and the abundance of Diptera pollinator groups. The negative impact of urbanisation on some pollinator groups was reduced in enhanced sites compared with control sites. Planting both pollinator-friendly ornamental plants and wildflower meadows significantly increased the visits from Diptera and the diversity in the plant–pollinator community compared with wildflower plantings alone. Our results suggest that enhancing public spaces for pollinators has positive effects on key groups and can help mitigate the impacts of urbanisation. Non-native ornamental plants can also play a role in enhancing green spaces for pollinators while maintaining their recreational functions. This supports a mixed-planting approach for improving public green spaces in urban areas for both people and nature.