Diverse natural spaces in urban areas have demonstrated health benefits to city-dwellers, have the potential to provide habitat to species of conservation concern, and help to combat the widespread decline in nature experience among urban dwellers. While many studies of these potential benefits focus on large urban greenspaces such as parks, smaller interventions may also increase the habitat value of urban landscapes. One of these is Green Stormwater Infrastructure (GSI), in which vegetated spaces are used to collect, treat, and transport urban stormwater. Bioretention basins, or rain gardens, are a popular GSI, but few studies have examined their ability to provide habitat for wildlife. Understanding the distribution and abundance of wildlife in these basins should yield perspective on their ecological value. Here we report on the first half of a long-term study of bird and insect communities in and near a GSI project that installed over 400 bioretention basins in Columbus, OH. We sampled birds via passive acoustic monitoring and carabid beetles via pitfall traps at several of these sites, and at nearby lawn sites for comparison. We used PERMANOVA to ask whether bird and carabid communities in bioretention basins were different from those in nearby lawns.
Results/Conclusions
Newly-installed bioretention basins hosted different carabid communities from lawns, and also hosted more carabids than lawns. However, we were unable to detect an influence of bioretention basins on urban bird communities. This is consistent with the small scale of bioretention basins relative to the habitat requirements of birds and of arthropods, respectively. Bird communities in nearby parks were significantly different from those in both lawns and in bioretention basins, showing the positive effect of larger urban green spaces on landscape-scale diversity. Bioretention basins, like other green infrastructure, change as they mature, and future work may reveal more or different effects on wildlife.