PARENT SESSION
Poster Session #46: Seed Production, Recruitment, and Pollination.
Friday, August 10, 2001. Presentation from 10:30 AM to 12:00 PM. Exhibition Hall

Relationships between floral resources and pollinator communities in Iowa prairie fragments.

Gienapp, Christopher¹, Hines, Heather¹, Hendrix, Steve¹, ¹

ABSTRACT- Gradual declines in plant populations and extinctions of forb species within prairie fragments may be a result of ineffective pollination because small, isolated plant populations are unable to attract and maintain sufficient pollinators for successful reproduction. Our goal is to determine if diversity of flower resources is an accurate predictor of pollinator species richness. We studied twelve prairie fragments ranging in size from 2 to 74 hectares in east-central Iowa in 2000. We conducted three censuses (late May, June, and July) to determine Shannon-Wiener diversity of the flowering forb community using number of flowering ramets of each species as a measure of abundance. Flowering forb richness ranged from 21 to 64 species and Shannon-Wiener diversity (log₂) ranged between 0.7 and 3.8 and was positively correlated with fragment size. We concurrently sampled flower-visiting insects to determine pollinator species richness for each site. Butterfly richness ranged from 2 to 19 species per site, while bumblebee richness ranged from 1 to 8 species per site. Butterfly species richness was positively correlated with flowering forb diversity, but not fragment size, while bumblebee species richness was not correlated with either. These preliminary data suggest flowering forb species diversity may be an accurate predictor of butterfly, but not bumblebee, species richness. We are currently analyzing data to determine if species richness of additional groups of bees are correlated with diversity of flower resources.

KEY WORDS: pollination, prairie, fragmentation