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 highdensity 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.

Pollinator competition and the structure of floral resources

“…The temporal structure of floral resources also obtains at the diel scale, where within‐day floral phenology interacts with within‐day patterns of pollinator foraging activity. At the species level, diel patterns of nectar production typically follow a three‐phase pattern consisting of periods of 1) secretion, 2) cessation and 3) resorption (Torres and Galetto 1998, Amorim et al 2013), resulting in a unimodal pattern of nectar availability (usually peaking in the morning) often mirrored by a corresponding pattern of pollinator visitation (Cavalcante et al 2018, Ballarin et al 2022). Notably, however, descriptions of diel patterns of nectar production and pollinator visitation come almost exclusively from single‐species case studies; it remains an open question how species‐level patterns combine to produce the community‐level patterns of nectar availability experienced by generalist pollinators.…”

The use and abuse of keystone plant species in restoration practices of terrestrial ecosystems

“…Moreover, overabundant keystone plants may excessively attract dominant alien pollinators to the habitat. For example, the use of Inga vera in abundance above that which naturally occurs in a Brazilian Cerrado undergoing restoration attracted mainly the dominant alien bee species, Apis mellifera , impacting native bees that provide essential pollination services for co‐occurring native recruited plants (Ballarin et al 2022).…”

Native Bee Habitat Restoration- Key Ecological Considerations from Recent Literature

“…Showy ornamentals can outcompete native plants for pollinators, compromise the nutrition of native bees, and disrupt coevolved pollination networks, often by promoting generalists over specialist bee species (Seitz et al, 2020;Tallamy et al, 2021). For example, planting tree species with copious nectar can disturb native bee communities and potentially favor non-native pollinators (Ballarin et al, 2022).…”