An ecosystem approach for sustainability: addressing the challenge of complexity

The dynamics of ecosystems and human systems need to be addressed in the co ntext of post-normal. science grounded in complex systems thinking. We port ray these systems as Self-Organizing Holarchic Open (SOHO) systems and inte rpret their behaviours and structures with reference to non-equilibrium the rmodynamics: holons, propensities and canons; and information and attractor s. Given the phenomena exhibited by SOHO systems, conventional science appr oaches to modelling and forecasting are inappropriate, as are prevailing ex planations 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 co nsidered. Short examples are given. We also link SOHO system descriptions t o issues of human preferences and choices concerning the preferred attribut es of particular SOHO systems, and to the implications for achieving them t hrough adaptive management, monitoring and appropriate structures for gover nance. 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 deci sion systems, for the practice of post-normal science. (C) 1999 Elsevier Sc ience Ltd. All rights reserved.