Submitted to: First Interagency Conference on Research in the Watersheds
Publication Type: Proceedings
Publication Acceptance Date: August 20, 2003
Publication Date: September 15, 2003
Citation: Skirvin, S.M., Moran, M.S. 2003. Rangeland ecological and physical modeling in a spatial context. Proceedings First Interagency Conference on Research in the Watersheds. Oct. 27-30, 2003, Benson, AZ. pp.451-454. Interpretive Summary: Computer models of plant growth and processes such as rainfall infiltration, runoff, and erosion in rangelands can assist researchers in understanding and predicting the results of changes in rangelands. One such model, SPUR (Simulation of Production and Utilization of Rangelands), was originally developed and released in 1987 and since then has been used and revised by a number of researchers in rangelands of the Great Plains and Texas. Researchers at the USDA-ARS Southwest Watershed Research Center in Tucson, Arizona, are determining how well the model can be adapted for the special conditions of semi-arid southwestern rangelands. The original SPUR model looks at a small, uniform area such as a grazing pasture or even smaller. The research described in this paper expanded the model to work for larger areas of mixed soils, vegetation, and topography, producing a digital Amap@ of results. The spatially explict version of SPUR, or SESPUR, is being tested at a study site in the Walnut Gulch Experimental Watershed near Tombstone, Arizona. Further research will try to simplify the model so that it can be used by land managers and other stakeholders to look at "what-if" scenarios.
Technical Abstract: The SPUR (Simulation of Production and Utilization of Rangelands) model has been in use and revision since 1987 in diverse rangelands including Texas and the Great Plains. The model=s applicability to semi-arid rangelands of the southwest is under evaluation at the USDA-ARS Southwest Watershed Research Center in Tucson, Arizona. As part of this effort, a spatially explicit implementation of SPUR (SESPUR) has been developed with the long-term goal of incorporating distributed hydrologic information from GIS-based hydrologic models such as SWAT (Soil and Water Assessment Tool) and KINEROS, as well as remotely sensed soil moisture. Ease of model use has been improved with the ability to display output with a GIS, and linkage to a database of input parameters will improve the user=s experience. Validation of the updated model is in progress with data obtained at the Walnut Gulch Experimental Watershed near Tombstone, Arizona. The original focus of SPUR included prediction of hydrologic and erosion changes resulting from management decisions, as well as simulation of forage growth and its utilization by grazing animals. Its usefulness for other biophysical and ecological modeling has been substantially enhanced with the SESPUR spatial implementation.