Why are qualitative models useful in ecology?
Models can be used to generate hypotheses. Models allow detailed predictions to be made about the ultimate effects of disturbances to the system. Qualitative models are typically drawn as diagrams that describe the relationships between components in an ecological community. A component is any variable such as a given species, or the temperature of the water in a stream. Components are connected with links that represent the type of ecological interaction, the flow of material, or a causal effect of one component on another, such as predation. Any combination of two or more components that have direct and indirect effects on one another is termed a “system.” The overall effect of any input from one component on another (direct and indirect) is observed and can be calculated. Aspects of this analysis can indicate the stability of the system calculated qualitatively (positive, negative, or none) rather than quantitative (exact numerical). Feedback loops, positive and negative links are a
