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An ecosystem approach, must have as its underpinnings, a system description. Otherwise it is not a systems approach, but a classification scheme.
George Francis, Henry Regier and I have been working with graduate students to develop a systems description of ecological systems which we refer to as a Self-organizing Holarchic Open Systems (SOHO) description. This systems description is well suited as a framework for ecosystem monitoring.
Central to the description is that self-organizing systems are composed of structures and processes. Self-organizing dissipative processes emerge whenever sufficient exergy is available to support them. Dissipative processes restructure the available raw materials in order to dissipate the exergy. Through catalyse, the information present enables and promotes some processes to the disadvantage of others . The physical environment will favour certain processes. The interplay of these factors defines the context for (i.e. constrains) the set of processes which may emerge.
Once a dissipative process emerges and becomes established it manifests itself as a structure. These structures provide a new context, nested within which new processes can emerge, which in turn beget new structures, nested within which... Thus emerges a SOHO system
The system which emerges is a function of its environmental context and history.
Change the context sufficiently, even if only temporarily, and major reorganization, a flip occurs. Cannot generally tie specific changes in context to specific changes in system organization. Rather we need to understand the rich interplay of context, history and the existing structures and processes. Linear casual explanations often don't work. (This is a major challenge for the pressure-state-response model as it ignores these system realities.)
Need to characterize the context; the processes and the structures; and understand their relationships in the current historical setting.
In the case of a vortex in bathtub water, the exergy is the potential energy of the water, the raw material is the water and there is no historical information, the dissipative process is water draining, the dissipative structure is the vortex. When there is enough height of water in the bathtub, and not before, the vortex will emerge. If too much height of water is present, the vortex flips into a different form of flow.
In an ecological setting, examples of structures are the individuals of species, breeding populations, forests etc. The processes are reproduction, metabolism, evapotranspiration etc. The context is the available set of nutrients and energy sources and the physical environment. The information includes the biodiversity.
Updated 1 July, 1999
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