First steps of pollinator-promoting interventions in Eastern European urban areas – positive outcomes, challenges, and recommendations

Urbanisation has a strong role in pollinator decline, while properly managed green spaces could promote pollinators – especially bees and butterflies – by providing foraging and nesting habitats in cities. In public spaces, several opportunities exist to help pollinators including rare mowing, flower strip sowing, and bee hotel establishment. However, pollinator-promoting interventions are almost lacking and still understudied in Eastern Europe. We aimed to investigate the impact of rare mowing and annual flower-sowing interventions on pollinators, floral resources, and vegetation attributes in three case studies within Hungary. We compared treatment (extensively mown or sown) and control (intensively mown) site pairs during five sampling occasions within a season. We found positive, but due to the severe drought and management inaccuracies relatively minor effect of both interventions. The extensively mown sites presented higher and greener vegetation with more flowers and pollinators. The sown flower patches provided floral resources and supported the pollinators in the second half of the season, while they were scarcely visited in spring and early summer due to the annual soil scarification and re-sowing. Although the two types of interventions could complement each other during the season, there is room for further improvements. To reach resilient urban ecosystems against climate and environmental changes, we recommend using primarily native and mostly perennial seeds, combining intervention types, planning for the long-term, and avoiding management inaccuracies (e.g. unplanned mowing). Promoting and monitoring plant-pollinators systems may increase the diversity and human well-being in cities, while citizens’ involvement can facilitate these interventions.