Elsevier, Ecological Modelling, (247), p. 144-156
DOI: 10.1016/j.ecolmodel.2012.08.018
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Human activities have an impact on environmental systems. In light of environmental sustainability assessment, methods are needed which quantify this impact. Ecological Network Analysis (ENA), a method to study and analyse ecosystem networks and their changes, could be an adequate tool to do so. However improvements to ENA are needed, described further on. We look specifically to the applicability in the field of life cycle assessment (LCA), a tool in which the total environmental impact of resource extraction and emissions during a product’s life cycle is quantified. To better quantify this impact in LCA, as a first objective, the alteration of ecosystems induced by those processes needs to be accounted for. As a second objective, the flow networks of ecosystems, responsible for the formation of the extracted resources, should be included in the product’s life cycle. In ENA, total system indicators are calculated which assess an ecosystem’s functioning (e.g. cycling). Alterations of ecosystems can be represented by changes in the values of those indicators (achievement of second objective). ENA is based on the computational framework of Input-Output Analysis (IOA). This framework is also used in LCA allowing for a possible extension of a product’s life cycle in an LCA with the ecosystem flow networks of ENA (achievement of first objective). The ENA/IOA framework itself was revised and improved in this study to better fit in an LCA framework, prior to integration and application in LCA. One adaptation was to enable physical compartmentalisation of the surrounding environment of the studied (eco)system. This allows for a specification of destinations and sources of export and import flows, respectively, which is desired in LCA to assess the impact of these flows. Next to that, the adapted framework was made applicable to non-steady state systems by applying Finn’s concept (1976, 1977), in which increase, increment, and decrease, depletion, in stock are considered abstract export and import flows, respectively. As an example, the adapted ENA framework was applied to a forest ecosystem. However, there are no standards yet for the different choices in the ENA methodology, which can have an influence on the indicator values. Hence, defining such standards is a next important research step.