Are Plant Communities of Roadside Stormwater Ponds Similar to those Found in Natural Wetlands?

Stormwater ponds (SP) are increasingly used for water management along roads and in urban environments. How these infrastructures compare to natural wetlands in terms of biodiversity remains unclear, however. Studies to date have evaluated the subject in general terms, without considering the different zones in SP and wetlands (from aquatic, at the pond edge, to terrestrial, at the upper bank) or other local and regional factors. In this project, we aimed to compare the taxonomic diversity and composition of plant communities established in four different zones of SP with that in either roadside or remote natural wetlands. We also evaluated the effect of various local and regional factors on those communities. Our results show that, globally, the species composition of the lower, wetter zones was similar between SP and natural wetlands, especially roadside wetlands, while higher, drier zones showed significant differentiation. Factors explaining observed differences between SP and both roadside and remote natural wetlands were water level fluctuations, road proximity, slope, and age of the SP. Stormwater ponds also exhibited lower beta diversity than both types of wetlands. Nonetheless, our study suggests that with some modifications in their design, SP have the potential to harbour more wetland plant communities.