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Portrait of Henrik Smith. Photo.

Henrik Smith


Portrait of Henrik Smith. Photo.

Early-season mass-flowering crop cover dilutes wild bee abundance and species richness in temperate regions : A quantitative synthesis


  • L. G.A. Riggi
  • C. A. Raderschall
  • T. P.M. Fijen
  • J. Scheper
  • H. G. Smith
  • D. Kleijn
  • A. Holzschuh
  • G. Aguilera
  • I. Badenhausser
  • S. Bänsch
  • N. Beyer
  • E. J. Blitzer
  • R. Bommarco
  • B. Danforth
  • J. P. González-Varo
  • H. Grab
  • G. Le Provost
  • K. Poveda
  • S. G. Potts
  • M. Rundlöf
  • I. Steffan-Dewenter
  • T. Tscharntke
  • M. Vilà
  • C. Westphal
  • Berggren
  • O. Lundin

Summary, in English

Pollinators benefit from increasing floral resources in agricultural landscapes, which could be an underexplored co-benefit of mass-flowering crop cultivation. However, the impacts of mass-flowering crops on pollinator communities are complex and appear to be context-dependent, mediated by factors such as crop flowering time and the availability of other flower resources in the landscape. A synthesis of research is needed to develop management recommendations for effective pollinator conservation in agroecosystems. By combining 22 datasets from 13 publications conducted in nine temperate countries (20 European, 2 North American), we investigated if mass-flowering crop flowering time (early or late season), bloom state (during or after crop flowering) and extent of non-crop habitat cover in the landscape moderated the effect of mass-flowering crop cover on wild pollinator abundance and species richness in mass-flowering crop and non-crop habitats. During bloom, wild bee abundance and richness are negatively related to mass-flowering crop cover. Dilution effects were predominant in crop habitats and early in the season, except for bumblebees, which declined with mass-flowering crop cover irrespective of habitat or season. Late in the season and in non-crop habitats, several of these negative relationships were either absent or reversed. Late-season mass-flowering crop cover is positively related to honeybee abundance in crop habitats and to other bee abundance in non-crop habitats. These results indicate that crop-adapted species, like honeybees, move to forage and concentrate on late-season mass-flowering crops at a time when flower availability in the landscape is limited, potentially alleviating competition for flower resources in non-crop habitats. We found no evidence of pollinators moving from mass-flowering crop to non-crop habitats after crop bloom. Synthesis and applications: Our results confirm that increasing early-season mass-flowering crop cover dilutes wild pollinators in crop habitats during bloom. We find that dilution effects were absent late in the season. While mass-flowering crop cultivation alone is unlikely to be sufficient for maintaining pollinators, as part of carefully designed diverse crop rotations or mixtures combined with the preservation of permanent non-crop habitats, it might provide valuable supplementary food resources for pollinators in temperate agroecosystems, particularly later in the season when alternative flower resources are scarce.


  • LU Profile Area: Nature-based future solutions
  • Centre for Environmental and Climate Science (CEC)
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • Lund university sustainability forum
  • Biodiversity and Conservation Science

Publishing year





Journal of Applied Ecology

Document type

Journal article


John Wiley & Sons Inc.


  • Ecology


  • dilution effects
  • floral resource
  • landscape composition
  • mass-flowering crops
  • pollinator abundance
  • pollinator richness
  • seasonal effects



Research group

  • Biodiversity and Conservation Science


  • ISSN: 0021-8901