A review of management actions on insect pollinators on public lands in the United States

Public lands face growing demands to provide ecosystem services, while protecting species of conservation concern, like insect pollinators. Insect pollinators are critical for the maintenance of biodiversity and ecosystem function, but it is unclear how management of public lands influence pollinator conservation. We found 63 studies investigating the effects of prescribed burning, logging, grazing, invasive species removal, revegetation with wildflower mixes, and hosting commercial pollinators, on native insect pollinators on natural and semi-natural ecosystems in the US and summarized the results across taxa and habitat types. Manual removal of invasive shrubs and revegetation with wildflower mixes had consistently positive effects on pollinators. Grazing had neutral effects on pollinators in the Great Plains, but negative effects elsewhere. Prescribed burning had neutral or positive effects for bees depending on the habitat type, with occasional negative effects on butterflies. Logging had neutral to positive effects that were more uniform across ecosystems and taxa than burning. Burning combined with logging benefited pollinators, even when burning or logging alone had no effects. Although poorly studied, hosting commercial pollinators may negatively affect wild bees through pathogen transmission and competition for floral resources. Despite the rapid accumulation of information on factors contributing to pollinator declines, the effects of management actions on pollinators remain understudied for many taxa and habitat types in the US. Improving our understanding of the effects of public land management on pollinators is essential to conserve ecosystem health and services required by society.