System dynamics is a mathematical modeling approach widely used in environmental studies as a tool for representing and simulating ecological systems, giving support to prediction and decision making. The knowledge sources for model design are, essentially, ecological data and human expertise. Interestingly, however, the direct influence of data properties on model design has been little explored. We hypothesise that property descriptions of ecological data (ecological metadata), such as functional, temporal and spatial relations between variables, can be used to guide and to substantiate structural modeling decisions. In this paper we address the use of formal descriptions as an approach to representing ecological metadata, enabling us to automatically draw links between these formal descriptions and ecological modeling. A working example is presented in detail to illustrate the approach.