Change in plant species composition on powerline corridor: a case study

Powerline Corridors Can Add Ecological Value to Suburban Landscapes When Not Maintained as Lawn

Electric powerline corridors are informal green spaces that encompass large areas of land and have the potential to support biodiversity in urban and suburban landscapes. However, the extent to which these corridors provide novel habitats compared to the surrounding landscape is unclear. Biodiversity in corridors is often compared to that of “natural” habitats despite the fact that the corridors are subject to frequent vegetation management. In urban and suburban landscapes, residential yards may provide a more appropriate comparison because they are a dominant type of green space and are also characterized by frequent vegetation management. We conducted a study of the biodiversity in suburban powerline corridors in northern Illinois, USA, and compared it to the biodiversity found in nearby residential yards. Our goal was to determine whether powerline corridors added ecological value to these suburban landscapes. We included three different management styles of powerline corridors: (1) frequently mowed and kept as lawn, (2) brush mowed on a five-year cycle (“old-field”), and (3) restored and/or maintained as native prairie. We measured the species richness and composition of plants, birds, and insect pollinators in corridors and yards. The corridor management types and comparison yards differed significantly in the richness of all three taxa, with old-field and/or prairie sites having greater species richness than mown corridors and/or comparison yards. Community composition also differed by management category. While the species richness of old-field sites tended to be high, prairie sites generally had more species of conservation interest. Our study shows that both old-field- and prairie-managed powerline corridors add habitat value to Midwestern U.S. suburban landscapes by providing alternative habitat types that support many species. Nonetheless, we suggest that managers looking to specifically support native and/or grassland specialist species in this region should manage sites as prairies when possible.