Iowa State University Study Identifies Two-Way Dependency Between Pollinators and Grassland Biodiversity

Iowa State ecologists find that excluding pollinators reduces plant diversity by 27%, warning of a "vortex" effect in restored prairie landscapes.

By: AXL Media

Published: Apr 14, 2026, 7:23 AM EDT

Source: Information for this report was sourced from EurekAlert!

The Reciprocal Nature of Pollinator-Plant Dynamics

While ecologists have long understood that diverse landscapes attract a wide array of pollinators, new research from Iowa State University confirms that the relationship is a two-way street. A study published in the journal Ecology demonstrates that pollinators are not merely passive beneficiaries of biodiversity but are active drivers of it. According to Brian Wilsey, a professor of ecology, evolution, and organismal biology, the presence of butterflies, bees, and other insects is a mechanical necessity for maintaining the variety of species within a plant community.

Experimental Methodology in Restored Prairies

The study was conducted over four growing seasons on approximately 50 acres of university land south of Ames. Researchers Brian Wilsey and Nathan Soley utilized 54 circular plots to test the impact of pollination on community-level diversity. To isolate the effects, the team covered tens of thousands of flowering plants with sheer fabric bags, which permitted light but excluded animal pollinators. Simultaneously, they augmented other plots by hand-pollinating flowers using Q-tips and paintbrushes to compare these results against undisturbed control areas.

Impact of Pollinator Exclusion on Seed and Species Viability

The results of the four-year exclusion were dramatic. Among the plants that depend on animal pollination, viable seed production decreased by 50 percent. More significantly, the overall diversity of species within the pollinator-excluded plots fell by 27 percent. This data represents the first time a study has quantified how a lack of pollinators can directly limit plant biodiversity at the community level. The findings help explain why restored prairies often lose their wildflower variety and become dominated by wind-pollinated grasses within just a few years.