MODELING HETEROGENEOUS ECOSYSTEMS WITH LARGE HERBIVORES

A spatially explicit landscape ecosystem model called SAVANNA has been used, further developed and updated for research and decision making in heterogeneous ecosystems with native and domestic large herbivores for over two decades. It is a generalized model that has been applied in a wide variety of habitats and vegetation types. Applications in the U.S. have included Rocky Mountain and Yellowstone National Parks, and the Pryor Mountain Wild Horse Range. Applications have also been developed in Eastern and Southern Africa, Australia, and Inner Mongolia. The most common uses have been assessments of sustainable ecological carrying capacity for large herbivores and assessments of ecosystem responses to climatic variability and change. A process based modeling approach is used to predict plant growth, vegetation dynamics, nutrient cycling, water budgets, and herbivore foraging, energetic status, and population dynamics. Spatial data are used to initialize the model and spatial-dynamic outputs can be viewed with the “Savanna Modeling System” or a GIS. Multiple plant and animal species or functional types can be simulated, enabling assessments of interactions between woody and herbaceous vegetation, effects of herbivory on vegetation composition and function, and interactions between wild and domestic herbivores. This presentation will provide an overview of this approach to spatially explicit ecosystem modeling.