Assessment of Arbuscular Mycorrhizal Fungi in a Green Roof System

Abstract

Green roof design has proceeded without integration of arbuscular mycorrhizal fungi (AMF). A literature survey was therefore conducted in order to determine which aspects of green roof functioning might be enhanced by AMF, and subsequently levels of AMF and endophyte colonization were determined for seven plant species used in green roofs. Plants were sampled from an experimental green roof and from the field. A commercial growing medium was also tested for AMF inoculum potential. Colonization was poor in both field and rooftop samples of the commercially popular succulent, Sedum acre, but significantly higher in Solidago bicolor, a proposed green roof species. The commercial growing medium was found to contain extremely low levels of viable AMF propagules. Although the apparent lack of mycorrhizal dependency of S. acre helps to explain its popularity as a green roof plant, its overuse precludes the important ecosystem services potentially provided by AMF symbioses.