S07 - Session P1 - Plant establishment and substrate performance in bioswales under a cold temperate climate

Authors: Jessica Champagne-Caron *, Monique Poulin, Guillaume Grégoire

Urbanization implies the impermeabilization of soils, leading to reduced water percolation and associated problems in rainwater management such as an increased of runoff volumes. Climate change, characterized by increased total annual precipitation and more frequent intensive rain events, will exacerbate this raise in rainwater flow, with detrimental impacts on water bodies, especially for cities where a combined sewer system is used. In this context, the use of green infrastructures, such as bioretention systems, to intercept and filter rainwater directly at the source has increased steadily in North America in the last few years. However, little data is available on the performance of plant species used in these types of system in cold temperate climates. The goal of this research project is to monitor the performance of 22 different plant species in 48 bioswales established in 2020 in a proximal suburb of Quebec City, South-Eastern Canada. Data were collected from July 2020 to October 2021 mainly during the growing season from May to September. Key parameters examined include survival rate, growth rate, mulch coverage, abundance and diversity of weeds, physicochemical properties of the growing substrate as well as leaf mineral content. Results from this study provide knowledge on the growth and performance of multiple plant species in bioretention systems and will be useful to elaborate recommendations for future bioretention systems in cold temperate climates.