Socio-Ecological Principles and Indicators for Sustainability
In this thesis I have developed science-based description models, concepts, measures and methods for use in the transformation of the societal metabolism towards sustainability.
The thesis is based on five papers: In Paper I, we analyse various factors that are important for the design of socio-ecological indicators. The purpose of the socio-ecological indicators is that they shall capture essential aspects of society's influence of nature in order to contribute to the control mechanisms that redirect society towards sustainability. Another important aspect of the socio-ecological indicators is that they shall focus early in the causal chain leading from activities in society to effects in nature.
In Paper II we develop and discuss four socio-ecological principles for a sustainable society: (i) Substances extracted from the lithosphere must not systematically accumulate in the ecosphere. (ii) Society-produced substances must not systematically accumulate in the ecosphere. (iii) The physical conditions for production and diversity within the ecosphere must not systematically be deteriorated. (iv) The use of resources must be effective and just with respect to meeting human needs.
The socio-ecological indicators for sustainability that are suggested in Paper III, are based on the socio-ecological principles of Paper II. The indicators are constructed so as to arrange the information in a systematic way. This leads to four complementary sets of indicators.
In Paper IV we define the environmental debt. It is known that today's society causes environmental damages that will remain for a long time or become manifest in the future. Such damages involve a debt to future generations because of the costs that they inflict on them. In the paper we use neo-classical economical theory to derive a method for estimating this debt.
In Paper V we analyse the stability of harvesting in a predator-prey model. The predator-prey system is a classical Lokta-Volterra type of model with one predator and two prey species. We compare the stability of two harvesting strategies, (i) constant quota and (ii) constant effort, and show that constant catch quota can lead to both oscillations (and chaos) and an increased risk for overexploitation.