System Dynamics Modeling: A Tool for Integrating Ecological Monitoring Data

The NPS Inventory and Monitoring program promotes development of scientifically defensible methods to track the condition of park resources. Following development of rigorous protocols for each ecosystem component, the next challenge is to use NPS and other data sets to describe ecosystem function by describing and quantifying species and environment interactions, thereby helping managers devise management strategies.  We developed a system dynamics model for the freshwater lifecycle stages of endangered coho salmon (Oncorhynchus kisutch) in Olema Creek, Point Reyes National Seashore, California, using Stella^® software to show how simulation modeling can be used to overcome common data integration challenges such as data sets that don’t overlap in time and space; insufficient time series data to detect trends; limited range of observed environmental conditions.  We show how a system dynamics structure—unlike traditional statistical data analytic techniques—can incorporate important relevant parameters, variables, and trends that may only be available from published literature, expert opinion, or as hypotheses.  We show how system dynamic simulation modeling provides a hands-on method for understanding ecosystem function, assess effectiveness of the monitoring program, and guide resource management.