Bumblebee-plant interactions in urban green spaces in Reykjavik

Abstract

Plant-pollinator communities are important for maintaining ecosystems, especially in urban areas suffering from habitat fragmentation and biodiversity loss. Counting visitation rates is a good tool for understanding complex plant-pollinator interactions that impact plant-pollinator communities and serve as an indicator of resilience. This study aims to shed light on the understudied plant-pollinator communities in urban green spaces in Reykjavik, Iceland. The research was conducted in the summers of 2018 and 2019. Weather variables were recorded, and bumblebee visitation rates were counted (flower visitations up to one minute) in four study sites. Weather varied significantly between the study sites (p < 0.05), but no differences in visitation rates could be observed between bumblebee species and between study sites. However, significant interactions between study sites and bumblebee species were found (p = 0.029). Temperature and plant availability seem to drive visitation rates that were significantly higher on alien plants in 2018 (p = 0.031), but not in 2019. When native Wild Thyme (Thymus praecox Opiz subsp. arcticus (Durand)) was included in 2019 significant interactions between study sites and plant species occurred (p = 0.014). In addition, Wild Thyme had the highest visitation rates making visitation rates on native plants significantly greater than on alien plants (p = 0.024). This highlights the importance of alien and native plants as foraging resources for bumblebees in urban green spaces in Reykjavik. Long-term monitoring is recommended to assess population dynamics and trends of bumblebees and other urban pollinators.