Impacts of mass flowering soybean on bee visitation rates of forest plants at different spatial scales

Abstract

Agricultural intensification promotes the loss and fragmentation of natural habitats, and negatively affects the provision of ecosystem services such as natural pollination of native plants and crops. Also, many crops produce large flower blooms for a short period of time, and some studies have found effects of this massive flowering pulse on the abundance and foraging behavior of pollinators. Particularly, soybean is one of the most extended crops globally, and its flowers are visited by native bees and honeybees. In this work, we evaluated the effects of mass flowering soybean at different spatial scales on visitation rates of co-flowering plants inhabiting in fragmented forests of central Argentina. We applied generalized linear mixed models and bootstrapping methods via a multi-scale approach, by defining circular landscapes of increasing radii, from 0.5 to 1.5 km, by 0.25 km intervals. Results show that the visitation rates on forest target plants by total flower visitors and honeybees increased with higher proportions of remnant forest, and a positive trend was found for native bees. Moreover, visitation rates by native bees decreased with increasing proportions of mass flowering soybean in the landscape, whereas visitation rate by honeybees showed a positive trend with increasing proportions of mass flowering soybean across all spatial scales. Our work highlights the importance of considering the crop matrix in landscape management for the conservation of functional biodiversity, including crops with apparently inconspicuous flowers, as these massive flowering pulses could affect pollinator foraging activity and therefore the pollination services delivered to native flora.