Pollinators in the city: Europe-wide synthesis evidences the relevance of biodiversity-friendly urban management

Pollinators receive considerable interest due to their fundamental role in ecosystem functioning and human well-being. Unlike farmlands, studies of urban pollinator-promoting interventions have only started to grow rapidly recently and have not yet been synthesised, hampering all the related policies. To fill this gap, a new study investigated the impacts of pollinator-friendly management compared to conventionally managed urban green spaces.

This research was led by the HUN-REN Centre for Ecological Research in collaboration with 28 European institutes. Published in Ecology Letters, the synthesis examines whether pollinator-promoting interventions have positive effects on vegetation, floral resources, and a broad range of pollinator groups. The findings show that urban pollinator-promoting interventions generally benefit plants and pollinators with taxon-, intervention-, habitat-, and spatio-temporal-specific differences.

The researchers compiled 28 primary datasets, covering 15 years and 12 countries, with 1,051 sampling sites within Europe. They analysed the general effects, as well as the differences between the intervention types, such as abandonment, extensive mowing, flower sowing, and combined practices, and the habitat types, such as parks, grasslands, road verges, and private and public gardens.

General results present mostly positive and never negative effects for pollinator-promoting interventions, while the details are also particularly fascinating. Lead author Dr. Gabriella Süle explains, “Our synthesis underscores the importance of biodiversity-friendly management practices in cities. All of these pollinator-promoting interventions can be applied not only in public spaces but also in private gardens, allotments, green roofs, and balconies, providing opportunities to improve the public perception of insects and taller vegetation with wildflowers.”

Impacts on pollinators appear to be stronger for flower sowing as intervention, road verges as habitat, and locations in Northwestern Europe. Dr. Viktor Szigeti notes, “Despite all the efforts to harmonise and compile wide-scale datasets, some limitations have become clear, e.g. for certain pollinator taxa (e.g. beetles), regions (e.g. the Mediterranean), and novel interventions (e.g. for ground-nesting insects). A synthesis always holds the potential to guide the next steps: the need is clear for longer-term and larger-scale studies encompassing multiple taxa, interventions, and habitat types, as well as sampling farmlands, cities, and protected areas simultaneously, even globally.”

Building on the collective expertise of 38 authors in pollinator ecology, the researchers identified knowledge gaps and proposed concrete actions to make urban environments more favourable for pollinators while also considering wider socio-ecological aspects. Dr. András Báldi notes, “Our synthesis also presents both ecological and socio-economic arguments and highlights potential pros and cons of pollinator-promoting interventions. Our recommendations draw attention to knowledge gaps and offer actions to make specific interventions more favourable primarily for pollinators while also integrating the residents’ needs.”

In the era of climate change and urban expansion, the threats, but also the available mitigation opportunities, make the enhancement of green spaces in urban settlements an urgent priority. To reach the ambitious goal of bringing people, plants, and pollinators together in multifunctional, resilient, and sustainable infrastructures, citizens and stakeholders will need to develop locally adapted, collaborative, and research-informed biodiversity initiatives.