Bumble bee abundance and diversity increase with the intensity of tallgrass prairie restoration intervention

Introduction Human land use intensification and the resulting habitat loss are primary drivers of insect pollinator declines. Habitat restoration offers a promising approach to counteract these declines, yet landscape‐level evaluations of bee responses to restoration and management remain limited. We conducted a 2‐year, landscape‐scale study in Wisconsin, United States, to assess how different intensities of tallgrass prairie restoration and management affect bumble bees ( Bombus spp.). Objectives This study aimed to determine whether (1) bumble bee abundance and diversity increase with active restoration, and (2) outcomes differ between low‐ (seeded only) and moderate‐intensity (seeded and managed with prescribed fire) interventions. Methods Using catch‐and‐release surveys, we measured bumble bee abundance and diversity at 32 sites representing a gradient in restoration intervention: no‐intervention (passive recovery), low‐intervention, and moderate‐intervention. Results Bumble bee abundance and diversity were higher at active restoration sites (low‐ and moderate‐intervention) than at no‐intervention sites. Although both abundance and diversity tended to be greater at moderate than low‐intervention intensities, these differences were not statistically significant. Bumble bee community composition also differed across intervention intensity, driven by shifts in dominant species (e.g. Bombus impatiens and B. griseocollis ). Rarer taxa, including endangered and vulnerable species, occurred only at active restoration sites, with the largest populations at moderate‐intervention sites. Across all sites, bumble bee responses were strongly and positively associated with floral abundance, but not with semi‐natural habitat in the surrounding landscape. Conclusion Our findings demonstrate that active grassland restoration can effectively increase bumble bee abundance and diversity, supporting its value as a conservation practice for pollinators.