Can powerline corridors provide pollinator habitat in a suburban landscape matrix?

Background/Question/Methods

Habitat loss and degradation are key issues in urban and suburban ecosystems, especially for pollinating insects. However, research suggests that managed green spaces, such as powerline corridors and residential yards, may serve as pollinator habitat in an otherwise inhospitable landscape matrix, depending on their vegetation management. In the Chicago metro area, some corridors are managed with mowing and herbicide (“mowed corridors”), some are rarely managed and therefore overgrown (“overgrown corridors”), and others have been planted with native prairie plants (“prairie corridors”). We examined the species composition of the plant and pollinator communities in Chicago suburbs within mowed and overgrown corridors, prairie corridors, and residential backyards surrounding the corridors. Data were collected on pollinator species richness and diversity, floral resource richness and diversity, and floral resource cover. We also used GIS to examine other possible matrix factors affecting pollinator communities including impermeable surfaces and proximity of trees and shrubs. We used these data to investigate whether vegetation characteristics of the corridors/backyards or characteristics from the surrounding landscape matrix affect the community of pollinators in each site, and whether corridors or backyards provide better pollinator habitat overall.

Results/Conclusions

Floral resource species richness was highest in prairie corridors. Powerline corridors (prairie, mowed, and overgrown) also consistently contained pollinator communities higher in abundance and richness than residential backyards. An increased species richness of floral resources in mowed and overgrown corridors was correlated with an increase in pollinator abundance and richness. Pollinator abundance and species richness of prairie corridors and residential yards was unrelated to the species richness of floral resources. In early summer, floral resource percent cover had a positive relationship with pollinator abundance and species richness, with this pattern being more pronounced for both mowed and overgrown corridors. In late summer, floral resource percent cover seemed to have no effect on pollinator abundance or species richness in any of our sites. We conclude that powerline corridors provide ecological value to the suburban landscape by serving as pollinator habitat within the surrounding urban matrix. We recommend that powerline companies and municipal planners consider the pollinator habitat quality of powerline corridors when making management decisions.