Contrasting effects of field boundary management on three pollinator groups

Abstract

Abstract Uncultivated field boundaries constitute a significant part of the remaining semi‐natural habitat in simplified agricultural landscapes, providing habitats for many grassland species. In Europe, agri‐environment schemes (AES) offer incentives to farmers to manage farmland more environmentally friendly. In Sweden, one AES has specifically targeted management of incidental habitats on farmland by promoting removal of woody vegetation to benefit cultural heritage and biodiversity. This study investigates if pollinating insects benefit from removal of woody vegetation and whether any such benefits depend on the structural complexity of the surrounding landscape. Using a nested study design, pollinator communities were compared in pairs of managed and unmanaged field boundaries in landscapes of different complexity. The effect of removing trees and bushes in field boundaries varied among pollinator groups. Bumblebee species richness and abundance benefited from the management, whereas the species richness of solitary bees and hoverflies were unaffected. The abundance of solitary bees was higher in managed field boundaries, but only late in the season in complex landscapes, while the same management lowered the hoverfly abundance particularly late in the season. Landscape complexity did not affect bumblebees, while the abundance of solitary bees and the species richness of hoverflies were positively correlated with increasing landscape complexity, but at different spatial scales. The contrasting effects of management on different organism groups shown in this study, illustrate the importance of studies conducted on multiple taxa. Management prescriptions based on results from one pollinator group may not benefit other pollinator groups.