A roadmap to modelling ecosystem services within an urban metabolism framework

Increasing urbanisation poses new and complex urban challenges. These challenges involve diverse economic activities driving the flows of materials and services through the urban system, influencing the health of ecosystems... [ view full abstract ]

Increasing urbanisation poses new and complex urban challenges. These challenges involve diverse economic activities driving the flows of materials and services through the urban system, influencing the health of ecosystems and resulting in socio-ecological impacts inside and outside the system boundary. In this regard, the least evident but undoubtedly relevant impacts are those that influence the capacity of urban and peri-urban ecosystems to supply their services. This paper critically reviews literature for state-of-the-art urban metabolism (UM) assessment methods from which we illustrate an innovative roadmap towards the modelling of urban ecosystem services (UES). UM is an established concept of material-energy stock and flow accounting for cities which this paper analysed for its application to mapping and assessing UES. On one hand the analysis showed that existing UM valuation techniques have limited capacity for spatio-temporal and multi-scale information, which so far has hampered the implementation of operational decision support systems. On the other hand, recent studies disclosing the benefits and costs of UES prove that benchmarking those services as associated with metabolic flows might be an extremely valuable solution to support sustainable urban planning. Seven key investigation issues were elected based on the findings of critical review papers used in the initial meta-review. The issues we identified are: sustainability scope, system boundary, model type, indicators, data types, spatiality, and temporality. A total of 44 UM papers were reviewed with regard to these seven key investigation issues. . No study demonstrated an ecosystem services approach, and while many studies used indicators that could easily be translated to UES indicators those studies were not comprehensive in their scope accros coupled human-nature systems. The literature invariably had limited scopes which risks accounting for indicators that give incomplete and unrepresentative results. To comprehensively assess UES a multi-scale, spatio-temporal systems approach needs to be adopted. Our critical review of UM and UES assessment methods and their tools suggests that system dynamics (SD) modelling should be integrated with the UM framework, based on spatially-specific social, economic and ecological data along with their coupled effects. As a result of this review we outline a roadmap towards such a SD UM modelling framework for UES assessment, with the long-term goal to provide a knowledge base tool that can support urban planners in addressing urban challenges. The proposed enrichments to the UM framework are anticipated to better inform urban planners on the long run consequences of deploying sustainability interventions with the goal of meeting urban and global sustainability challenges.

Keywords: urban metabolism, socio-ecological impacts, spatio-temporal dynamics, multi-scale, sustainability, ecosystem services