Intra-seasonal and daily variations in nectar availability affect bee assemblage in a monodominant afforested Brazilian Cerrado

Abstract

Nectar is the most common floral resource that mediates plant–pollinator interactions, and its spatiotemporal distribution is related to pollinator attraction and can influence pollinator activity through time. Therefore, assessing patterns of floral phenology of nectar-producing plants can help better understand the pollinator assemblage's temporal dynamics. We used an area of afforested Brazilian Cerrado covered with a high-density plantation of Inga vera, a mass-flowering nectar-producing tree, to investigate whether intra-seasonal and daily variations in nectar availability provided by I. vera flowers affect the bee assemblage. We showed that bee abundance was positively related to intra-seasonal patterns in floral phenology and daily changes in nectar production. Although bee species richness was also associated with intra-seasonal changes in nectar availability, bee diversity (quantified using Simpson's diversity index) did not follow the same pattern. We suggest that the dominance of the invasive honeybee, Apis mellifera, on I. vera flowers may have affected the overall bee diversity over time due to an exacerbated increase in honeybee abundance. Therefore, by evaluating the temporal dynamics of nectar availability, an important floral attribute that influences plant–pollinator interactions, we suggest that planting high-rewarding tree species at high densities in open ecosystems can affect the dynamics of native bee assemblages negatively due to the exacerbated recruitment of the dominant exotic honeybee.