Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2002
Publication Date: 11/2/2002
Citation: Pierson, F.B., Spaeth, K.E., Weltz, M.A., and Carlson, D.H., Hydrologic response of diverse western rangelands. Journal of Range Management, v.55, no. 6, p. 558-570. Interpretive Summary: Many simplifying assumptions are made about what controls infiltration and erosion from all rangelands in order to develop ways to universally predict runoff and sediment delivery across the entire spectrum of rangeland types. Many exceptions to such assumptions exist making it difficult to make universal predictions. This paper uses a comprehensive data set of vegetation, soils, hydrology and erosion from diverse western rangelands to assess the validity of many assumptions for rangelands. The data set emphasizes the difficulty in understanding and predicting the hydrologic response of semiarid rangelands. The relationship between plant and soil characteristics with infiltration and erosion processes is not well established. Infiltration and sediment production are not universally related to any measured vegetation or soil characteristic. Many factors determine infiltration and erosion dependent on rangeland type and site conditions. Universal algorithms representing the hydrologic and erosion responses of all rangeland types will never provide accurate enough estimates to be useful in assessing management impacts. We need to develop a way to organize rangeland types according to similarities in soil, vegetation and hydrologic characteristics in order to develop more accurate and specific predictions useful in the management of rangelands.
Technical Abstract: Several assumptions concerning rangeland hydrology and erosion relationships have been used by modelers as justification to develop one universal algorithm to describe a process across the entire spectrum of rangeland types. Modeling approaches based on the "universal" concept may not be appropriate for diverse rangeland types. This paper uses a comprehensive data set of vegetation, soil, hydrology and erosion from diverse western rangelands to assess the validity of various assumption for rangelands. The data set emphasizes the difficulty in understanding hydrologic response on semiarid rangelands, where the relationship between plant/soil characteristics and infiltration/erosion is not well established. Infiltration and sediment production are not universally correlated with any measured vegetation or soil characteristic. A myriad group of factors determining infiltration and erosion, and is dependent on rangeland type and site conditions. Universal algorithms to represent the response of all rangeland types, such as the pooled multiple regression equations presented, will not provide sufficient accuracy for prediction or assessment of management impacts. We need to develop the means to organize rangeland types according to similarities in relationships and responses to assist in the development of more accurate and specific predictive equations to enhance model performance and management of rangelands.