Green roofs provide resources for native forbs and bees in Chicago

Background/Question/Methods

Although many publications state green roofs have the potential to provide habitat for native flora and fauna, few studies have directly measured if green roofs provide these ecosystem services. Native plant performance is currently being evaluated on green roofs throughout North America, however few results are available from long-term monitoring projects. Even fewer studies have made connections between green roof adapted native plants and the organisms they support with foraging and nesting materials. Over the past five years green roof ecology research in Chicago has provided initial insight into bee communities found on green roofs and their impact on native plant reproduction in this unique urban environment.  

Results/Conclusions

Though bee communities found on green roofs are less diverse and abundant compared to nearby ground-level bee communities of gardens, parks and prairies, native forbs on green roofs do not experience pollen limitation. These results suggest that a subset of the larger, local pollinator community may be sufficient for maintaining native plant populations. There is a correlation between green roof vegetation and the bee community found at a site. Overall, floral diversity is positively correlated with bee diversity. This research is ongoing and will be expanded in the future to answer broader questions regarding the ability of green roofs to contribute to overall urban biodiversity.