Root traits influence stormwater performance in a green roof microcosm

Abstract

Water uptake from vegetation can govern plant productivity through different mechanisms in natural terrestrial ecosystems. However, the ability of plants to regulate water can be viewed as an ecosystem service in urban regions, where vegetation in constructed ecosystems can help reduce stormwater runoff through their root systems. However, there is no knowledge on how root traits operate in extensive green roofs, an increasingly popular form of green infrastructure, as the substrate environment has an extremely shallow substrate depth (~20 cm) and a lack of biological legacy. In this study, I found that stormwater performance is not solely a function of rooting depth; rather, a multitude of belowground traits govern water regulation in this novel ecosystem that may optimize transport capacity, soil exploration and root construction costs. Overall, this study parallels findings from natural ecosystems and provides practitioners with new tools to create a more functional green roof.