Ecosystems supply a wide range of goods and services to mankind. This ranges from various goods produced in ecosystems, such as timber and fish, to the so-called life support services, for example the regulation of climatic and biochemical processes. Human pressure on ecosystems has been progressively increasing, and there is a need to ensure the optimal management of the current stock of ecosystems. This requires management that is both economic efficient and sustainable.
The traditional models assumed that ecosystems respond in a gradual, reversible manner to stress. However, increasingly, it is recognised that many ecosystem show much more complex dynamics, such as irreversible responses to stress and multiple states separated by thresholds. In this thesis, a framework and an ecological-economic modelling approach have been developed that can be used to analyse the efficiency and sustainability of management options for complex ecosystems. The framework is tested in three case studies. In the first case study, the optimal rotation period is determined for a forest subject to complex dynamics. The second study focuses on the De Wieden wetlands in the Netherlands. The economic value of the ecosystem services supplied by De Wieden are calculated, and, subsequently, the optimal level of eutrophication control is determined. In the third study, the optimal grazing density in the Ferlo semi-arid rangeland in Senegal is calculated.
The thesis demonstrates how complex dynamics influence the efficiency and sustainability of ecosystem management options. Complex dynamics need to be accounted for in the formulation of management plans for specific areas, as well as in the preparation and implementation of environmental policy, such as the European Water Framework Directive.