Pollinator Diversity and Network Dynamics in Urban Green Spaces

Sammanfattning

Urban environments may act as a refuge for pollinators in agricultural surroundings and mitigate the current decline of pollinator populations. Previous studies have shown that urban environments may enhance pollinator communities but different kinds of urban green spaces have varying effects. This study aims to compare the pollinator diversity and network dynamics of three kinds of urban green spaces namely, designed plant communities, sown meadows and semi-natural grasslands, which are commonly found in today's city-landscape. The green spaces differ in management intensity and floral communities with varying levels of native and non-native flora. The study sampled 36 sites in a blocked design across seven Swedish cities during the months May–August in 2025. Interactions between pollinating insects and flowers were recorded in 1x1 m sampling squares and compiled into plant-pollinator networks. Measurements of abundance, richness, diversity and network nestedness, modularity and specialisation were compared. The results demonstrate a clear difference in pollinator abundance among the studied green spaces, with highest abundances in designed plant communities. Network configuration showed no distinct difference among green space types. Network level-, pollinator- and plant specialisation were affected by green space type and were most specialised in semi-natural sites. Further, the results show that non-native plant species are significantly more generalised than native plant species. In conclusion urban green space management has an effect on pollinator communities in terms of abundance and network specialisation. Flower abundance and flower richness are important factors in green space amelioration for pollinators and non-native plant species may provide more resources towards the end of the season whereas native flowers are important for the conservation of specialised species. Different kinds of green spaces can play different roles in mitigating pollinator declines and should be considered in urban planning.