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Data from: Heathland pollinator communities are more strongly influenced by land use management than by honey bee competition

Brett, Maisie1; Mijares, Lisa1; Vaughan, Ian2; Memmott, Jane1

Published Aug 06, 2026 on Dryad. https://doi.org/10.5061/dryad.v6wwpzhc5

Data files

Aug 06, 2026 version files 1.04 MB

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Abstract

Managed honey bees have the potential to compete with wild pollinators. Pollinator populations are also affected by land management such as grazing, but how this mediates competition with honey bees is not well understood. Many competition studies are short-term, lack appropriate controls, or do not consider the impacts of hives on the interactions of whole plant-pollinator communities. Our objective was to assess the effects of apiaries and two land management strategies (grazed/burned vs. regenerating) on wild plant and pollinator populations in upland heathlands. We used a landscape-scale before-after control-impact experiment where apiaries were introduced to half of 20 sites, with the remainder left as controls. From May to September, we recorded at each site: a) habitat structure and nectar phenology, b) plant-pollinator network structure, and c) mass and protein: lipid ratio of pollen collected by bumblebees (which have high dietary overlap with honey bees). We found that nectar phenology and pollinator community composition were strongly driven by land management. For example, grazed sites had 63% less nectar available to bumblebees in spring due to sheep browsing of Vaccinium, but supported more abundant and diverse fly communities in the summer, associated with increased grass cover and habitat heterogeneity. Whilst plant-pollinator network metrics were unaffected by apiary introductions, nestedness and pollinator robustness were lower at regenerating sites. The mass and protein: lipid ratio of bumblebee-collected pollen were consistent across treatments. Synthesis and applications: Apiaries had modest impacts on heathland plant-pollinator communities, likely buffered by the abundance of Calluna vulgaris, which provides 91% of landscape nectar during hive introductions. We recommend avoiding hive introductions outside of peak flowering periods and managing grazing in the spring to ensure nectar resources for emerging pollinators. Heathland management strategies that encourage habitat heterogeneity, such as conservation grazing, could support abundant and diverse pollinator communities that are more robust to disturbance such as hive introductions.