Vegetation and Media Characteristics of an Effective Bioretention Cell

Abstract

A seven-year-old bioretention cell in Silver Spring, Maryland was surveyed for vegetation and media characteristics 11 months after last maintenance. Volunteer plants constituted more than half of the cell vegetation. Eutrochium dubium (Joe Pye weed) had the most coverage of all plant species at 43%. Average longest root length for the three examined species was 29.1 cm, and was not statistically different among the species. E. dubium had the thickest roots, with its thickest root diameter averaging 2.2 cm, and an extensive root structure. E. dubium also had the tallest above-ground biomass, averaging 88.7 cm. Spatial Mehlich 3 phosphorus profiles indicated P accumulation in the top 6 cm of media and decreasing P concentrations with depth. No indication of breakthrough in regard to P saturation was found. Based on the findings of this study, E. dubium is recommended for bioretention vegetation due to its survivorship and root structure. Additionally, the high percentage of volunteer species suggests the importance of vegetation maintenance planning.