Wider road verges sustain higher plant species richness and pollinator abundance in intensively managed agroecosystems

Landscape fragmentation and farming can affect the diversity of plants and pollinators harbored by linear landscape elements (LLE) in agroecosystems. To assess the role of these habitats in sustaining plant-pollinator communities, twenty portions of LLE (road verges) were studied during two consecutive field seasons in the Argentine Pampas. A hierarchical approach was taken, describing three features of road verges in different scales of observation: width of the road verge (local scale), the land use of the neighboring fields (adjacent land use scale), and landscape heterogeneity (landscape scale). The influence of these features on the composition and abundance of entomophilous flowering plants and their visitors were examined with GLMMs. Plant and flower visitor communities in road verges were dominated by alien species. The local scale feature was the most influential, as the widest road verges had higher plant richness and higher flower visitor abundance. Contrary to our expectations, richness and abundance of both plants and flower visitors were not related to adjacent land use or landscape heterogeneity. These results suggest that the conservation and management of wider road verges should be a priority to sustain high species diversity in intensely managed agroecosystems.