COS 9-9 - The effects of rangeland management strategies on pollinators

Monday, August 8, 2011: 4:20 PM
9C, Austin Convention Center
Kristen A. Baum, Integrative Biology, Oklahoma State University, Stillwater, OK and Kenneth E. Wallen, Zoology, Oklahoma State University, Stillwater, OK

Natural grasslands have undergone extensive habitat fragmentation and loss, with less than one percent remaining today. Therefore, the contribution of managed grasslands to biodiversity and as refuges for native plants and animals has become increasingly important. Pollinators are an important component of grassland ecosystems, with the potential to modify the structure of plant communities because of their influence over plant reproductive success. Many grassland remnants are managed as rangelands, but the effects of rangeland management strategies on pollinators have rarely studied. Rangeland management strategies can impact pollinators by modifying the distribution, abundance and diversity of floral resources (pollen and nectar) and nest sites. We evaluated the effect of the three dominant rangeland management strategies in the Great Plains on the bee community at managed rangeland sites in Oklahoma. We evaluated the effects of grazing, herbicide, and fire using a standard protocol for sampling bees with a combination of pan trap and netting surveys.


More than ninety species of bees were collected over the duration of the study. Bee species richness was higher in sites with heterogeneous versus homogeneous burning regimes. Grazing intensity did not affect the abundance or diversity of bees, but the difference between moderate and moderate to heavy stocking rates may not have been sufficient to identify an impact. Herbicide application did not appear to affect the abundance or diversity of bees, but results were confounded by the effectiveness of sampling methods relative to floral resource availability. The results of this study indicate that rangeland management strategies influence the structure and composition of the bee community, with important implications for the conservation of native bees and the availability of pollination services at larger spatial and temporal scales.

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