Data for: Pollinators maintain biodiversity in assembling plant communities

We did an experiment testing the effect of three levels of pollinator visitation on all forb flowers in plant communities of a prairie restoration. These pollination treatments were a pollinator exclusion treatment, an augmented pollination treatment, or a control, and were carried out within plots of different graminoid/forb seed ratios. The split plot design consisted of 11 different graminoid/forb ratios applied to 55 whole plots, and the pollination treatments were carried out in subplots within each whole plot. We sampled seed heads of 8 common animal-pollinated forbs to compare excluded vs. controls on number of germinants in the seed rain in 2021 and 2022. We sampled plant diversity within the subplots at the quadrat and subplot scale in 2023. Pollinator exclusion treatments resulted in 50% less germinants from the seed rain, 23% lower plant species richness, and 27% lower animal-pollinated forb richness. Also, the positive relationship between forb abundance and plant richness seen in augmented and control subplots was eliminated with pollinator exclusion. These results suggest that pollinator decline may be leading to a plant-pollinator extinction vortex. This study suggests, for the first time we are aware of, that plant biodiversity at the community level can be limited by animal pollinators.