Green roofs: plant production and installation methods

摘要

Green roofs involve growing plants on rooftops, thus replacing the vegetated footprint that was destroyed when the building was constructed. They can be categorized as 'extensive' or 'intensive' systems depending on the plant material and planned usage for the roof area (Dunnett and Kingsbury, 2004; Getter and Rowe, 2006).Extensive green roofs typically are not accessible to the public and may not even be visible. Because of their shallower media depth [<15 cm (6 in)], plant species are limited to herbs, grasses, mosses, and drought tolerant succulents such as Sedum. In addition, they usually require less maintenance than intensive green roofs and can be built on slopes. In contrast, intensive roofs are designed to be similar to landscaping found at natural ground level for park-like settings that are usually open to thepublic. They typically utilize a wide range of plant species that may include trees and shrubs, require deeper media layers [usually >15 cm (6 in)], require more maintenance, and are generally limited to flat roofs. Shallow extensive roofs are much morecommon than the deeper intensive roofs due to costs and weight restrictions (Figure 1).