Introduction: Frontiers of green roof ecology

Abstract

Green roofs are an increasingly visible component of urban environments. Also called living roofs or ecoroofs, green roofs are likely the oldest example of the purposeful merging of the built environment with living ecosystems—an early form of living architecture. This technology is allied with other constructed ecosystems such as green walls, also known as living walls or biowalls and green facades, and can be viewed as part of a wider phenomenon of the engineering of ecosystems to provide desired functions that benefit people (Ranalli and Lundholm 2008). We view green roofs as urban ecosystems that are increasingly relied upon to provide services that mitigate some of the negative impacts of cities (Oberndorfer et al. 2007). While the economic benefits of green roofs are one of the main drivers of the expansion of this industry, there has been comparatively little attention paid to green roofs as ecosystems, and little acknowledgement that green roofs are worthy of attention from ecologists. This special issue features eight articles originally presented as part of the Green Roofs for Healthy Cities annual conference held in Minneapolis in 2007. Green Roofs for Healthy Cities is a non-profit industry association whose mission is to increase the awareness of the economic, social and environmental benefits of green roofs and green walls and other forms of living architecture. Next year’s conference will be held in Atlanta in June and a call for papers for that event is out. Several of the papers here add to the growing number of studies that document the basic benefits of green roof ecosystems: stormwater retention, summer cooling, and the augmentation of urban biodiversity. These are well known benefits, but the work presented here defines the frontiers of our knowledge of green roof systems in areas such as biodiversity and ecosystem functioning, winter thermal benefits, air pollution mitigation, and ecological succession. Urban Ecosyst DOI 10.1007/s11252-008-0070-y