PARENT SESSION
Oral Session #89: Biodiversity and Ecosystem Function III.
Presiding: R. Washington-Allen
Thursday, August 8. 1:00 PM to 3:45 PM. Coconino Meeting Room, TCC.
Bee diversity and pollination services in an agro-natural landscape.
Kremen, Claire1, Williams, Neal*,1, Thorp, Robbin2, 1 Princeton University, Princeton, NJ2 University of California-Davis, Davis, Ca
ABSTRACT- Communities of native bees can provide a valuable ecosystem service by pollinating crops. Such service supplies motivation for the conservation of natural habitat within agro-natural landscapes. We investigated how natural habitat distribution and farm management practices influenced the diversity and abundance of a native bee community, and how this affected the pollination services they provided to a target row-crop, watermelon (Citrullus lanatus). On farms located different distances (near versus far) from native habitat and using different management strategies (organic versus conventional), we assessed visitation rates and per-visit pollen deposition. From these data we calculated the contributions of all bee species to watermelon pollination. The native bee community (>30 species) provided sufficient pollination on farms in the most favorable environment (near-organic). On farms far from natural habitat, native bees did not consistently meet pollination requirements, due to greatly reduced diversity and abundance; this effect was stronger on conventional than organic farms. Even on the organic farms near natural habitat, diversity was important for pollination function due to year-to-year variation in the composition of the pollinator community and species abundances. Farmers on far-organic and conventional farms usually relied on rented honeybee colonies to make up the pollination shortfall. At near-organic farms, honey bees were too rare to provide full pollination for watermelon and native bees are a critical to pollination service. Degradation of the agro-natural landscape is likely to destroy or severely reduce this service.
KEY WORDS: pollination, ecosystem service, native bees, habitat isolation