Disturbance Mosaics Shape Multiple Pollinator Taxa Across Spatial and Temporal Scales in Fire-Managed Forests.

Because forests are critical to a large fraction of global pollinator diversity, there is great interest in better understanding how changes in forest cover, structure, and composition affect these essential organisms. Fire is one of the key drivers of such changes worldwide, yet the effects of variation in fire regimes on pollinator communities remain poorly understood. We tested how fire history, roads, and tree composition jointly influence the richness, abundance, assemblage composition, and trait structure of bees, butterflies, and hover flies in a fire-managed forest landscape in the southeastern United States. We evaluated a wide range of spatial and temporal scales. Fire richness, defined as the number of unique fire histories surrounding a sampling location, was positively associated with bee and hover fly richness and with butterfly and hover fly abundance, although the most informative scales differed among taxa and responses. Fire frequency was positively associated with bee richness and butterfly abundance and with the abundance of several focal species. Relationships with roads differed among taxa: bee richness and abundance increased with surrounding road length, whereas butterfly abundance decreased. Local forest structure and composition also correlated with pollinator richness, abundance, and assemblage composition. Canopy openness correlated positively with bee richness and abundance, the proportion of pine correlated positively with butterfly abundance but negatively with hover fly abundance, and local tree richness showed a weak positive correlation with the proportion of bees classified as forest-dependent. Taken together, these patterns illustrate that conserving pollinators in a changing world will require managing landscapes to sustain diverse disturbance histories and compositionally distinct tree assemblages that maintain a broad range of habitat conditions.