The behaviour of cities: Theoretical framework for Urban Metabolism from an ecological perspective

Abstract

In order to cope with the global pressure for natural resources due to the urban development, cities need to be approached as systems. Urban metabolism popularizes as a concept to analogise ecological to urban systems so, links and connections operating in cities could be explained from an ecological perspective. This research develops a conceptual framework to analyse the role of metabolism in ecological dynamics and paralleled it with the urban dynamics, in order to set the theoretical basis for urban metabolism. The relation between metabolism and dynamics in ecological systems was based on a review of the metabolic theory of ecology. This was illustrated by characterizing different categories such as levels of organization, patterns, variables, mechanisms and drivers. Qualitative data from urban energy systems was analysed upon these categories with the purpose of contrasting urban and ecological dynamics. Implications for the regulation of dynamics as well as for the conceptualization of urban metabolism were drawn by integrating knowledge from both fields. In ecological systems, metabolism was found to perform a regulatory process in which constraints at the organism level gives rises to the higher levels of the organization upon conditions of limited resource supply. In the urban context, there was no evidence of such regulatory process. Flexibility of the components that describe the system as well as communication across levels, are fundamentals for the regulation of the dynamics in urban systems. In addition, the acknowledgment of conditions of limited resource supply might stimulate strategies for constraining the use of energy and for the shift in the perception of energy from a materialistic view to a more services oriented one. Then, urban metabolism considers a multilevel approach of cities in which regulation at the individual level unleashes different patterns at the higher levels. This gives the possibility to create an emergent behaviour along which less resource is required as the system enlarges. This proposes a change in the current trends of “using more for more” or “doing more with less” to a different philosophy of “using less for more”.