title: Historical nectar assessment reveals the fall and rise of floral resources in Britain.
abstract: There is considerable concern over declines in insect pollinator communities and potential impacts on the pollination of crops and wildflowers. Among the multiple pressures facing pollinators, decreasing floral resources due to habitat loss and degradation has been suggested as a key contributing factor. However, a lack of quantitative data has hampered testing for historical changes in floral resources. Here we show that overall floral rewards can be estimated at a national scale by combining vegetation surveys and direct nectar measurements. We find evidence for substantial losses in nectar resources in England and Wales between the 1930s and 1970s; however, total nectar provision in Great Britain as a whole had stabilized by 1978, and increased from 1998 to 2007. These findings concur with trends in pollinator diversity, which declined in the mid-twentieth century but stabilized more recently. The diversity of nectar sources declined from 1978 to 1990 and thereafter in some habitats, with four plant species accounting for over 50% of national nectar provision in 2007. Calcareous grassland, broadleaved woodland and neutral grassland are the habitats that produce the greatest amount of nectar per unit area from the most diverse sources, whereas arable land is the poorest with respect to amount of nectar per unit area and diversity of nectar sources. Although agri-environment schemes add resources to arable landscapes, their national contribution is low. Owing to their large area, improved grasslands could add substantially to national nectar provision if they were managed to increase floral resource provision. This national-scale assessment of floral resource provision affords new insights into the links between plant and pollinator declines, and offers considerable opportunities for conservation.
authors: School of Biological Sciences, University of Bristol, Life Sciences Building, Bristol BS8 1TQ, UK.|Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK.
authors: Mathilde
authors: M
authors: Baude
authors: School of Biology, University of Leeds, Leeds LS2 9JT, UK.
authors: William E
authors: WE
authors: Kunin
authors: Fera Science Ltd., Sand Hutton, York YO41 1LZ, UK.
authors: Nigel D
authors: ND
authors: Boatman
authors: Fera Science Ltd., Sand Hutton, York YO41 1LZ, UK.
authors: Simon
authors: S
authors: Conyers
authors: School of Biological Sciences, University of Bristol, Life Sciences Building, Bristol BS8 1TQ, UK.|Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK.
authors: Nancy
authors: N
authors: Davies
authors: School of Biology, University of Leeds, Leeds LS2 9JT, UK.
authors: Mark A K
authors: MA
authors: Gillespie
authors: NERC Center for Ecology &Hydrology, Bailrigg, Lancaster LA1 4AP, UK.
authors: R Daniel
authors: RD
authors: Morton
authors: NERC Center for Ecology &Hydrology, Bailrigg, Lancaster LA1 4AP, UK.
authors: Simon M
authors: SM
authors: Smart
authors: School of Biological Sciences, University of Bristol, Life Sciences Building, Bristol BS8 1TQ, UK.|Cabot Institute, University of Bristol, Bristol BS8 1UJ, UK.
authors: Jane
authors: J
authors: Memmott
mesh_terms: D000818:Animals; D044822:Biodiversity; D035264:Flowers / Q000737:chemistry* / Q000145:classification / Q000254:growth & development*; D065948:Grassland; D007313:Insecta / Q000502:physiology; D029902:Medicago / Q000737:chemistry / Q000254:growth & development; D057048:Plant Nectar / Q000032:analysis*; D010944:Plants / Q000737:chemistry* / Q000145:classification* / Q000378:metabolism; D054817:Pollination; D013045:Species Specificity; D006113:United Kingdom
chemical_list: D057048:Plant Nectar