Print PageBackground/Question/Methods
With increasing urbanization, countless native habitats are being altered by anthropogenic factors. In many cases, how native species respond in these modified and novel habitats is still unknown. One such example is green roofs, which are increasingly being installed in urban areas and could potentially provide usable habitat for many species. To date, most green roof research has focused on minimizing environmental impacts of buildings but little is known about the ecological services they provide. Previous research has shown that although green roofs do get visited by a number of bee species, there are far fewer than at adjacent ground level sites. This lack of potential pollinators could result in pollen limitation and poor seed production. The current investigation is a first attempt at understanding what pollination services are available on green roofs and whether or not these ecosystems have the ability to function as sustainable habitats. Nine native Illinois prairie plant species and their pollinator communities were studied on 4 green roofs and at 4 ground level locations in the Chicago area. Pan traps were used to assess the pollinator communities at all sites and supplemental pollination treatments were used to look for evidence of pollen limitation.
Results/Conclusions
Our results support previous studies, showing a significantly lower presence of bees at green roofs when compared to the ground level. Averaged across all species at our study sites we found no significant difference between supplemental and open pollinated treatments. However, green roofs and ground locations were found to significantly differ in the percent of maximum seed set produced, surprisingly green roofs having a higher overall mean percent maximum seed set than the ground sites. As a consequence, the abundance of potential pollinators was negatively correlated to the seed set data. Together, these data suggest that although green roofs may contain a smaller and less diverse community of pollinators, the insects that are present are providing sufficient pollinator services to not limit plants’ reproductive abilities.
