Determinants of Species Richness and Abundance of Bumble Bees, Bombus spp. (Hymenoptera: Apidae), In Montane Meadows of the Sierra Nevada, California

MASTERS THESIS: California has experienced a greater fractional loss of wetland area than any other state in the United States. The importance of high elevation wetlands to biodiversity is nowhere more evident than on the arid eastern slope of the Sierra Nevada. Since the majority of vascular plants rely on insects for pollination, insects are excellent indicators of ecological processes as well as patterns. Bumble bees are important pollinators of both wild and cultivated plant species in the habitats in which they exist. However, we understand very little about the factors that contribute to the diversity of bumble bees. To determine the factors that contribute to the species richness and abundance of bumble bees, I investigated both local and landscape properties of montane meadow in the eastern Sierra Nevada, California. Both local and landscape factors emerge as important predictors of bumble bee species richness and abundance indicating that conservation efforts for bumble bees must use a landscape approach to identify properties that are important for the conservation of this important pollinators.... To determine the properties of meadows that contribute to the diversity of bumble bee species in the Sierra Nevada, I examined six local attributes: elevation, composition of floral resources, meadow area, meadow perimeter to area ratio, meadow moisture, and grazing regime. Additionally I examined two landscape level attributes: distance to the nearest meadow, and proportion of the surrounding habitat that is meadow habitat.