Prescribed fire increases the number of ground-nesting bee nests in tallgrass prairie remnants

Abstract

Prescribed burning is a common management technique in tallgrass prairie remnants, but there have been few empirical studies that directly examine burning impacts on the nesting preferences and habitat of ground-nesting bees. We used emergence traps in remnant tallgrass prairies in western Minnesota, USA to determine whether ground-nesting bees prefer to nest in burned or unburned prairies. We estimated the total number of nests made by actively nesting bees in burned and unburned patches by assessing each specimen for wing and mandible wear, sex, and sociality. We also measured characteristics that may influence bee nesting preferences including bare ground, thatch depth, vegetative cover, and the floral community. We found more nests of actively nesting ground-nesting bees in burned patches than unburned patches, but no differences in effective number of species of ground-nesting bees or community composition. Burned patches had higher amounts of percent bare ground and a thinner thatch layer, but no differences in percent vegetative cover, floral abundance, flowering plant species richness, effective number of species of flowers or community composition. Our results suggest that ground-nesting bees prefer to nest in burned patches of remnant tallgrass prairies and highlight opportunities for future research to better understand bee nesting ecology in response to prairie management.