Field sizes and the future of farmland biodiversity in European landscapes.

Lower diversity of plant and animal farmland species are usually reported where cropland has been aggregated into larger fields, which raises prospects of curbing declines in European farmland biodiversity and associated ecosystem services by halting trends to field size increases associated to agricultural intensification, without having to set aside arable land for conservation. Here, we consider the factors underlying trade-offs between farmer income and biodiversity as mediated by field size at local and landscape scales, and how these trade-offs may be overcome. Field sizes are still increasing, facilitated by increasing farm sizes and land consolidation. Decreases in working time and fuel expenses when fields are larger, uptake of larger machinery and subsidies favoring larger farms provide incentives to manage land in larger units, putting farmland biodiversity further at risk. Yet, field size-mediated ecological-economic trade-offs are largely ignored in policy and research. We recommend internalizing the ecological effects of changes in landscape-scale field size into land consolidation scheme design, ensuring that EU Common Agricultural Policy post-2020 rewards farmers that maintain and recreate fine-grained landscapes where these are essential for farmland biodiversity targets, and reducing economic-ecological trade-offs by stimulating agricultural research and innovation for economically efficient yet biodiversity-friendly farming in fine-grained landscapes.