Do habitat restorations actually increase bumble bee populations? A population genetics approach to evaluating restoration success

Revised Abstract: Habitat restoration may mitigate declines in bumble bee populations, but restored habitats require regular management to maintain their quality. For example, in the Upper Midwestern USA, tallgrass prairie restoration requires intentional, controlled burning (i.e., prescribed fire) to maintain plant abundance and diversity. Although restorations often target plant communities, they may affect bumble bees as well through improved food and nesting resources for bees. However, management activities such as the use of prescribed fire may also influence bees directly through mortality. We surveyed individual bumble bee abundance and nest density in 2021 and 2022 across Southern Wisconsin at tallgrass prairie restorations that varied in their fire history. We expected that the number of individual bees would be higher in recently burned sites due to increases in flowering plant abundance following fire. In contrast, we expected the number of nests would be lower in recently burned sites due to destruction of nesting resources by fire. The effects of prescribed fire in restored tallgrass prairie on bumble bee communities throughout their life cycle must be better understood to make proper land management decisions.