Plant/Pollinator Interactions in Fragmented Landscapes
Winfree, Rachael , Williams, Neal M. , Fagan, William F. , Cariveau, Daniel P. .
How do plant communities structure bee communities in fragmented habitats?
Despite the ubiquity of alien plant species in fragmented ecosystems, their impact on native pollinator communities has been little investigated. We asked whether alien plants provide important food resources for native bees in disturbed habitats, and whether bee abundance and species richness change with changing alien plant abundance. At sites in California and New Jersey, we sampled plants and bees in replicated plots in both natural and disturbed habitat types. We found that in disturbed habitats, bees visited alien plants significantly more often than native plants (P<0.001 in both studies), whereas in natural habitats this was not the case. However, bees did not exhibit a preference for alien plants in either study, and alien plant abundance was not associated with bee abundance or species richness. We further investigated a possible mechanism through which plant communities might structure bee communities. We predicted that the extent of continuous bloom in a given habitat, which can be extended in fragmented systems by the presence of alien plants, acts as a filter on bee communities to exclude bee species with periods of adult activity that extend beyond the period of bloom. We tested this hypothesis using data on bee and plant communities at 26 sites in New Jersey, 14 of which were in extensive natural areas and 12 of which were in disturbed habitats. Consistent with our hypothesis, we found greater temporal gaps in bloom at the natural sites (F=34.0, P<0.0001), and greater bee species richness at the disturbed sites (F=8.0, P<0.02). However, a simple model that predicts bee species richness as a function of plant and bee species phenology explained a small proportion of the variance in observed bee species richness across sites. We conclude that the match between plant and pollinator phenologies is a minor force in structuring bee communities in this system.
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1 - Rutgers University, Entomology, 93 Lipman Dr, New Brunswick, NJ, 08901, USA
2 - University of California, Davis, Entomology, Davis, CA, 95616, USA
3 - University of Maryland, Biology, College Park, MD, 20742, USA
4 - Rutgers University, Entomology, New Brunswick, NJ, 08901, USA
Presentation Type: Symposium or Colloquium Presentation
Location: 552B/Convention Center
Date: Wednesday, August 4th, 2010
Time: 4:15 PM