Types of Conceptual Models

A Conceptual Ecological Model (CEM) is often presented as a diagram with accompanying text, but the form, complexity, and content can be customized to suit the application.

• Control Models – illustrate feedbacks and interactions between ecosystem components, such as the feedbacks between light, turbidity and vegetation in aquatic ecosystems.
• State and Transition Models – diagram changes between alternative ecosystem states, such as shifts in vegetation composition during ecological succession.
• Driver-Stressor Models – describe the linkages between agents of ecosystem change and ecosystem attributes; for example, the linkages between management of stream flows and fish communities.

The format of a CEM may be narrative, tabular, or schematic.

• Narrative CEMS generally articulate hypotheses in brief statements, formulae, or combinations of both. Complex ecosystems may require extended narratives, whereas simpler models may be articulated in a few sentences or paragraphs.
• Tabular or Matrix CEMs present ecosystem components as an array and can vary in complexity depending on the number of elements included in the table or matrix.
• Schematic CEMs can take many forms, including pictures or box-arrow diagrams.