Co-benefits from tree planting in a typical English agricultural landscape: Comparing the relative effectiveness of hedgerows, agroforestry and woodland creation for improving crop pollination services

Land use policy in England is encouraging tree planting on farms to meet decarbonisation targets. This could be delivered through woodland creation, hedgerow planting or agroforestry. All three approaches could provide cobenefits for wild bee populations and crop pollination services, by increasing nesting and floral resources, but their relative effectiveness has not been studied at a landscape scale. We simulated six tree planting scenarios and used a validated process-based model to predict their effect on bumblebee abundance and pollination service to two common mass-flowering crops (oilseed rape and field beans) in a representative 10x10km agricultural landscape in England, UK. Two levels of planting intensity were studied: one representing the tree cover that would be achieved by 2035 if the 2020 woodland creation rate continues and another reflecting UK Government ambitions (threefold increase in planting rate). Hedgerow planting and woodland were predicted to give the biggest increase bumblebee abundance. Silvoarable agroforestry using fruit trees or willow was predicted, on average, to give the biggest increase in crop pollination service. However, the magnitude of increase was highly variable and hedgerow creation (which is more dispersed across the landscape) provided a more consistent increase in crop pollination services. Agroforestry with poplar (which offers less floral resource) and woodland creation (which concentrates tree planting in fewer locations) were only effective at enhancing landscape-level crop pollination at high planting intensity. Future land management policy should promote fruit tree and willow based agroforestry as multifunctional tree planting measures in arable contexts, whilst continuing to encourage hedgerow planting and woodland creation for their role in promoting abundance and diversity of pollinators. Hedgerow planting may be needed alongside agroforestry to help stabilise pollination service through a crop rotation cycle