Green roofs may cast shadows

Abstract

A “green roof” is a roof on a structure created by humans, which has a plant community (and various hangers-on) established on it. There are many potential benefits of green roofs, ranging from moderation of local microclimates to modulations of storm runoffs, and green roofs may serve the enhancement of biodiversity conservation, as well. Green roofs would seem to be quintessential examples of a “novel ecosystem”. Here, I first outline some dimensions of the novelty that warrant more research. Green roofs can provide many opportunities for creative ecological research in the assembly, dynamics and functioning of novel ecosystems. Then, I briefly discuss some potential biodiversity hazards that are created along with green roofs. Recognizing these potential “shadows” of a green roof by no means belies the strong and compelling rationale for promoting green roofs, in terms of sustainability and livability of human structures; instead the points I raise are simply issues which should be evaluated and quanti...