A ‘green’ chameleon: Exploring the many disciplinary definitions, goals, and forms of “green infrastructure”

While the concept of green infrastructure (GI) is increasingly popular, definitions, terminology, and goals differ based on geographic and disciplinary context. This paper examines these differences through a three-part systematic review: 1) content analysis of academic GI review publications, 2) bibliometric review of academic publications focusing on GI and GI-associated terms, and 3) an online search for grey GI literature. Parsing out conceptualizations of GI, and the agendas they support, helps us better understand its probable outcomes in different contexts. We find that urban planning, urban forestry, ecology, engineering, landscape architecture, and law have epistemic claims to GI, and use divergent conceptualizations to implement the concept. Moreover, there are a number of related concepts, each of which is associated with a distinct scholarly community. These different conceptualizations and terms can be grouped into three primary categories: GI as 1) a greenspace planning concept, 2) an urban ecology concept, and 3) a water/stormwater management concept. Cutting across these categories we find the ecosystem services concept, a focus on specific engineered facility types, and a gradient of implicit GI definitions. A surprising number of publications (41% of those reviewed here) do not define GI, which can cause confusion or lead to implementation of GI projects that fail to meet expectations. We therefore argue that scholars and practitioners need to be explicit and specific about how they are defining GI and its purpose to avoid the siloing of research and practice and to take advantage of opportunities to address multiple agendas simultaneously.