Diversity and Competition in Bee-Plant Communities on Short-Grass Prairie

Abstract

Several diversity-related measures (richness, H', hierarchical information, species abundance distributions) are used to examine the hypothesis that members of the bee guild of high-altitude, shortgrass prairie compete for limited floral resources. Data on bee and flower populations was collected for two years at two sites. We reasoned that competition should be reflected by: (1) similar species abundances distributions for bees and flowers; (2) strong positive correlations between the total flower abundance of a species and the number of bee visitors; (3) strong positive correlations between bees and flowers in diversity and abundance when samples were taken at frequent intervals. Results are generally inconsistent with the hypothesis that either bees continuously compete for floral resources or vice-versa. Instead, the data support the hypothesis that competition is intermittent due to (1) a spatiotemporally unpredictable resource base, (2) the fact that adult bees are the products of the previous years resource supply rather than that available in the year of emergence.