A broader framing of ecosystem services in cities: Benefits and challenges of built, natural or hybrid system function

People derive benefits from ecosystems, their components and their processes. These benefits, called ecosystem services, are often taken for granted (i.e. the cool shade provided by a tree) or sometimes beyond everyday perception (e.g. the ‘purifying’ role of rivers in reducing pollutant inputs). The diverse suite of services proffered by natural ecosystems is categorized by the Millennium Ecosystem Assessment (MEA, 2005) and others (e.g. de Groot et al., 2002) into provisioning (production functions), regulating (regulation functions) and cultural (information functions) services. A fourth MEA category, supporting services, is not considered here because these are the ecosystem processes that underpin the above mentioned services. Likewise, biodiversity cannot be considered a service except insofar as it provides aesthetic enjoyment benefits to people, although it may or may not underpin the ecosystem processes that yield services. deGroot et al. (2002) also recognize habitat functions, i.e. the places for organisms to live and reproduce, as services that ecosystems provide.