Railway lines affect spatial turnover of pollinator communities in an agricultural landscape

Aim Landscape composition and spatial configuration of habitat patches are important determinants of biodiversity in fragmented semi-natural habitats spread across agricultural landscapes. However, little attention has been paid to man-made structures that can moderate spatial processes affecting pollinator communities. In a large-scale study, we explored the importance of railway embankments for the turnover of pollinator species in agricultural landscapes. Because species differ in vulnerability to landscape composition and patch configuration, we also accounted for body size as well as food specialization of pollinators. Location Krakow area, Poland. Methods We sampled pollinating insects (bees, butterflies and hoverflies), at 25 study sites located along railway lines in the region of Krakow, Poland. Control grasslands for the embankments included 19 patches, located among crop fields, in which pollinators were sampled. We assessed the relationships between dissimilarity and distance for bee, butterfly and hoverfly trait groups on embankments and grasslands using Moran's Eigenvector Maps. Results The dissimilarity for food-non-specialized bees on embankments was spatially structured: sites that were closer together were also less dissimilar in their community composition than more distant ones. Dissimilarity was also spatially aligned for large-bodied butterflies and hoverflies on embankments. The species dissimilarity of pollinators divided into trait-based groups was not spatially structured on grasslands. Main conclusion Our study highlights the potential function of railway embankments as corridors for at least some pollinator populations. Landscape managers should include railways in green networks to improve spatial processes linked with the distribution and turnover of pollinator species in agricultural landscapes. Thus, railway embankments and their correct management may be a good example of man-made alterations in the environment that meet the demands of both civilization and biodiversity conservation.