Vegetation root and media characteristics in bioretention

Bioretention systems manage stormwater through the use of ecological processes and rely on complex interactions between vegetation, root dynamics, growing media properties and stormwater retention. Parameters of three distinct growing media and three vegetation palates in a mature bioretention research facility were investigated in relation to stormwater retention performance in an arid, cold- climate region.
This data was collected June through August, 2024, as part of an MSc. Environment and Management thesis.

Stormwater retention ranged from 0% to 67%, was highest in coarser media and demonstrated significant interactive effects of media and vegetation. Improved Vegetation recruitment and the formation of water stable aggregates was improved in clay loam media. No clear connection between vegetation root length density and stormwater retention was found, while shrub dominated beds exhibited the highest root length density. Vegetation that persisted demonstrated adaptions to challenging environmental conditions which can enhance long-term bioretention performance.
This study confirmed that media and vegetation have a complex interaction with stormwater retention. Bioretention design trade-offs must harmonize sandy media content for suitable stormwater event retention, while incorporating clay and organic materials for pedogenesis and vegetation recruitment. The connections examined between stormwater retention, media properties, vegetation success, and root parameters improve the overall understanding of the components influencing long-term success of stormwater bioretention in arid, cold-climate regions.