An ecosystem approach for sustainability: addressing the challenge of complexity

The dynamics of ecosystems and human systems need to be addressed in the context of post-normal. science grounded in complex systems thinking. We portray these systems as Self-Organizing Holarchic Open (SOHO) systems and interpret their behaviours and structures with reference to non-equilibrium thermodynamics: holons, propensities and canons; and information and attractors. Given the phenomena exhibited by SOHO systems, conventional science approaches to modelling and forecasting are inappropriate, as are prevailing explanations in terms of linear causality and stochastic properties. Instead, narratives in the form of scenarios to depict morphogenetic causal loops, autocatalysis, and multiple possible pathways for development need to be considered. Short examples are given. We also link SOHO system descriptions to issues of human preferences and choices concerning the preferred attributes of particular SOHO systems, and to the implications for achieving them through adaptive management, monitoring and appropriate structures for governance. A heuristic framework to guide reasoning for this is presented, and reiterative steps for applying it are identified. In this way we provide a coherent conceptual basis, in the workings of both natural systems and decision systems, for the practice of post-normal science. (C) 1999 Elsevier Science Ltd. All rights reserved.