Published in:Proceedings of the Royal Society B: Biological Sciences
Language:
English
DOI:
10.1098/rspb.2011.0268
ISSN:
0962-8452;
1471-2954
Origination:
Footnote:
Description:
<jats:p>
Agricultural land use results in direct biodiversity decline through loss of natural habitat, but may also cause indirect cross-habitat effects on conservation areas. We conducted three landscape-scale field studies on 67 sites to test the hypothesis that mass flowering of oilseed rape (
<jats:italic>Brassica napus</jats:italic>
) results in a transient dilution of bees in crop fields, and in increased competition between crop plants and grassland plants for pollinators. Abundances of bumble-bees, which are the main pollinators of the grassland plant
<jats:italic>Primula veris</jats:italic>
, but also pollinate oilseed rape (OSR), decreased with increasing amount of OSR. This landscape-scale dilution affected bumble-bee abundances strongly in OSR fields and marginally in grasslands, where bumble-bee abundances were generally low at the time of
<jats:italic>Primula</jats:italic>
flowering. Seed set of
<jats:italic>Primula veris</jats:italic>
, which flowers during OSR bloom, was reduced by 20 per cent when the amount of OSR within 1 km radius increased from 0 to 15 per cent. Hence, the current expansion of bee-attractive biofuel crops results in transient dilution of crop pollinators, which means an increased competition for pollinators between crops and wild plants. In conclusion, mass-flowering crops potentially threaten fitness of concurrently flowering wild plants in conservation areas, despite the fact that, in the long run, mass-flowering crops can enhance abundances of generalist pollinators and their pollination service.
</jats:p>