A framework for interdisciplinary understanding of rivers as ecosystems

Understanding and managing the behaviour of rivers as ecosystems requires holistic, interdisciplinary approaches. However, we lack appropriate frameworks to guide interdisciplinary thinking because disciplinary paradigms lose their usefulness in the interdisciplinary arena. Conceptual frameworks are useful tools with which to order phenomena and material, thereby revealing patterns and processes. A framework for the interdisciplinary study of river ecosystems is presented in this paper. The framework presents parallel hierarchies in the geomorphology, hydrology and ecology of a river with different organizational elements and levels of organization for each discipline. It assigns spatial and temporal scales for each level of organization for the different discipline hierarchies whereby different parts can be distinguished by different frequencies of occurrence and/or rates of change. Integration of the different disciplines, within the context of a particular study, is represented by a flow-chain model that describes process interactions that can change an ecosystem from one state (a template) of biophysical heterogeneity to another (a product). The framework concept is applied by first describing in detail the relevant organizational levels that characterize the different subsystems of the river ecosystem in the context of the problem being addressed. This is followed by the identification of appropriate scales and variables within the different organizational levels. Then the interactions with the products of template/agent of change/controller interactions that may account for any feedback influences are described. A series of examples is provided to illustrate the use of the framework in various interdisciplinary settings.