The effect of management practices on bumblebee densities in hedgerow and grassland habitats

Large-scale declines in pollinator species are a concern at present. Such declines have been attributed to a range of factors that act in tandem, rather than in isolation. Some of the most pervasive factors affecting pollinator populations are habitat loss and degradation, which results in the loss of floral resources, nesting sites and landscape connectivity. Intensification of agriculture and urbanisation are two major causes of such habitat alterations. Hedgerows and grasslands are two vital habitats for pollinators in European landscapes. When managed appropriately, these habitats may provide abundant floral resources and nesting opportunities, as well as connectivity between habitats in a fragmented landscape. This study examined the effects that management practices of hedgerows and grasslands may have on bumblebee species, an important group of wild pollinators. Bumblebee abundance was recorded using transect walks in managed and unmanaged sites, including both hedgerows and grasslands. Greater densities of bumblebees were found in unmanaged grasslands in comparison to managed grasslands. Unmanaged hedgerows were also found to have a greater density of bumblebees than managed hedgerows. These results indicate that sites which are less intensively managed provide a more suitable habitat for bumblebees. Therefore, our study underlines the importance of (a) enforcing restrictions on hedge-cutting, and (b) reducing the management intensity of grasslands to provide adequate habitat for pollinators.