Impacts of delayed grazing and mowing on bumblebees and flowers in species rich grasslands

Abstract Species-rich grasslands are key habitats for bumblebees. Intensive agricultural practicessuch as frequent mowing and high grazing pressure have led to significant declines infloral resources in grasslands, contributing to pollinator declines. We investigated theeffects of delayed mowing and delayed grazing on bumblebee and floral communitiesin species-rich grasslands in north-west Ireland. Using a paired field design, wemonitored bumblebee and floral abundance, species richness, and diversity, over twogrowing seasons under both delayed and conventional management regimes. Bothdelayed mowing and delayed grazing significantly increased floral and bumblebeeabundance. These effects were most pronounced for common than rare bumblebeespecies, which may be related to the later emergence of rare species that requireresources later in the season when grazing or mowing has been reinstated. In thedelayed and conventional mowing fields, some pre-existing differences in floralabundance were present so further work is needed to confirm findings of this treatment.Overall, we demonstrate that adaptive land management strategies—particularly thosethat reduce summer time disturbance—can enhance bumblebee communities and floralresources, and can be used for bumblebee conservation in agricultural landscapes. Implications for Insect Conservation: Delaying mowing and reducing grazing pressure can measurably enhance floralresources and support bumblebee abundance. Incorporating such practices into agri-environment schemes, and supporting farmers with their implementation, can improve habitat quality and promote long-term conservation of bumblebees in grasslandlandscapes.