Landscape composition influences pollinators and pollination services in perennial biofuel plantings

Biofuel cropping systems are considered a potential source of renewable energy and an integral component of a sustainable energy policy. The type of biofuel crop selected for production has the capacity to substantially alter landscape composition, affecting biodiversity conservation and ecosystem services. To understand how increasing production of perennial grasses for biofuels may affect pollinators and pollination services, we identified 20 agricultural fields that varied in their proportion of surrounding grassland cover. Bees and pollination services were measured at each site to determine how bee abundance, diversity, and community composition responded to increasing proportions of grassland, and to quantify how pollination services changed as the proportion of grassland increased in the landscape. Bees were collected from sentinel sunflowers, and pollination services were measured by comparing seed set from open and closed sunflowers at each site. Landscape composition had a significant effect on bee abundance, diversity, and community composition with a greater abundance of bees and a more diverse bee community found visiting flowers at sites with more of the surrounding landscape in perennial grassland. In contrast, the bee community in low grassland sites was dominated by Apis mellifera, suggesting that pollination in these landscapes may be more sensitive to declines in this species. Despite these differences, the level of sunflower pollination was similar across sites, even though the bee community responded to changes in landscape composition. Increasing grassland cover through the addition of perennial biofuel plantings would be expected to support a more diverse bee community and a greater abundance of bees, yielding reliable pollination services.