Role of management in the long-term provision of floral resources on farmland

Abstract

Floral abundance and richness on farmland has been declining since the mid 1900 s. Agri-environment schemes (AES) can improve floral resource availability through establishment of flower-rich areas or careful management of areas set-aside to naturally regenerate on farmland. Ideal management regimes include sowing and re-sowing of seed mixes, regular cuts of growth, and removal of cuttings to optimise floral diversity. Our aim was to determine which areas and managements on farmland provided greatest floral resources for insect pollinators, and if these persisted over time. We surveyed 67 non-crop areas across eight farms in the south of England during 2014 and again in 2018, recording each flowering species present and the estimated floral abundance of each species. We then interviewed the farmers to determine management details and history for each surveyed area. Our results showed that floral abundance was initially greatest in sown Pollen & Nectar Strips and Florally Enhanced (FE) Grass Margins, but subsequently declined: from 1 to 5 years to 6–10 years for Pollen & Nectar Strips, and from 1 to 10 years to 11–20 years for FE Grass Margins. Additionally, only a handful of sown species known to be beneficial for insect pollinators persisted over time: Centaurea nigra, Lotus corniculatus, Trifolium pratense and Leucanthemum vulgare. It is vital that policy makers move forward with pollinator-targeting AES that can successfully support a variety of insects, including both pollinators and crop-pest predators. Species lists for AES seed mixes should include higher proportions of persistent perennial species, and a better support structure is needed in order to aid farmers with AES managements.