Planting for pollinators: Can current restoration mixes attract and conserve bees?

Background/Question/Methods

Global pollinator declines have highlighted a need for the development of pollinator focused conservation efforts to preserve this valuable ecosystem service. Because we lack specific information for most pollinator species, restoration of native plants is considered a primary technique to conserving pollinators.  However, this assumes that standard restoration plants are preferred foods for pollinators. This is despite restoration plants being chosen for a number of reasons aside from pollinator diet including plant community structure, seed availability, ease of planting and viability within a restoration. We wanted to determine if standard prairie mixes could aid in conserving a significant number of pollinator species. Using extensive records on plant-pollinator interactions in remnant Iowa prairies, we simulated the bee communities that could assemble using standard prairie mixes.  We also simulated the bee communities that would assemble if alternate methods were used to choose plants such as plant species abundance in remnant prairies and plant species that had higher bee species associations.  

Results/Conclusions

Although prairie mixes offer an easy method to begin restoring native plant diversity, species accumulation curves showed that these plant species accumulated fewer bee species at a much slower rate than choosing plants based on bee associations or abundance in remnant prairies. Interestingly, five additions to standard prairie mixes could restore an additional 50% of bee species. Some premier prairie mixes included some of these bee attractive species. This suggests that if money is spent to choose more expensive and more diverse prairie mixes there is a greater chance of success for attracting pollinators.  In conclusion, although restoration could improve native bee conservation more targeted efforts need to be made to succeed in conserving pollinators.