Abstract

The species richness of flower-visiting insects has declined in past decades, raising concerns that the ecosystem service they provide by pollinating crops and wild plants is threatened. The relative commonness of different species with shared ecological traits can play a pervasive role in determining ecosystem functioning, but information on changes in abundances of pollinators over time is lacking. We gathered data on relative abundances of bumble-bee species in Swedish red clover fields during three periods in the last 70 years (1940s, 1960s and present), and on clover seed yields since 1921. We found drastic decreases in bumble-bee community evenness, with potential consequences for level and stability of red clover seed yield. The relative abundances of two short-tongued bumble-bees have increased from 40 per cent in the 1940s to entirely dominate present communities with 89 per cent. Average seed yield declined in recent years and variation in yield doubled, suggesting that the current dependence on few species for pollination has been especially detrimental to stability in seed yield. Our results suggest a need to develop management schemes that promote not only species-rich but also more evenly composed communities of service-providing organisms.

Keywords

Bombus spp.; ecosystem service; pollination; Trifolium pratense; red clover

Published in

Proceedings of the Royal Society B: Biological Sciences
2012, Volume: 279, number: 1727, pages: 309-315
Publisher: ROYAL SOC

SLU Authors

• Bommarco, Riccardo

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Lundin, Ola

  • Department of Ecology, Swedish University of Agricultural Sciences
    

• Rundlöf, Maj

  • Department of Ecology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Agricultural Science


Publication identifier

DOI: https://doi.org/10.1098/rspb.2011.0647

Permanent link to this page (URI)

https://res.slu.se/id/publ/56467