Development of context specific sustainability criteria for selection of plant species for green urban infrastructure: The case of Singapore

Abstract

Sustainable urban development at the global level results from sustainable actions undertaken at city, neighbourhood and household levels with the right balance of environmental, economic and social aspects, achieved through initiatives such as water sensitive cities, sponge cities and “active, beautiful and clean waters ” (ABC waters). Green infrastructure (GI) including parks, green roofs, green walls, rain gardens and swales contribute to sustainable development of cites. Even when the overall selection of GI based on life cycle analysis and life cycle costs is satisfactory, the selection of suitable plant species is a challenge as the theory and practice of selecting plants for GI is poorly understood and lacking. Thirty eight out of fifty one plants species used in Singapore GI are not native species and eighteen are weeds. Although not necessarily sustainable these plant species contribute to make Singapore attractive and clean. This research focused on developing a comprehensive plant selection criteria “Criteria for green infrastructure Sustainable Outcomes in Urban Precincts” (CgreenSoup) for sustainable GI based on social, environmental, economic and engineering aspects. The ecological aspects of plant species also comprise the criteria prevalent in allelopathic and toxicological assessment of plants in countries such as Australia, Singapore and USA. The relevance of CgreenSoup was tested by assessing the plant composition of the GI implemented through the Active, Beautiful and Clean Waters Features program (ABC Waters) in Singapore. Based on the outcomes in the Singapore context, the methodology developed in Cgreensoup can be used for the selection of plant in contexts such as sponge cities, to avoid negative ecological impacts and achieve benefits that are more sustainable. From this, it is strongly recommended that a set of selection criteria collectively contributing to ecological health should be used for the selection of plants as part of GI for ensuring sustainable outcomes in urban landscapes.