The Spatial and Temporal Influence of Vegetation on Surface Soil Factors in Semiarid Rangelands

Abstract

Technology for modeling runoff and erosion on rangelands has improved, but improvements in simulation accuracy are often lost in techniques used to estimate model parameters. This is particularly true on semiarid rangelands which have significant spatial and temporal variations in runoff and erosion processes. The spatial distribution of the amount and kind of vegetation is an important factor controlling infiltration and erosion rates on rangelands. Improvements in model parameter estimation techniques and in our understanding of vegetation and soil induced variability are needed to increase our hydrologic and erosion predictive capabilities for rangelands. The role vegetation performs in controlling the spatial and temporal variability of surface soil properties that influence infiltration and erosion on semiarid rangelands was investigated using data representing a northwest sagebrush plant community and a southern great plains bunchgrass/sodgrass plant community. Vegetation was found to be the primary factor influencing the spatial and temporal variability of surface soil processes controlling infiltration and interrill erosion rates on semiarid rangeland. On sagebrush dominated landscapes, vegetation growth form (e.g., bunchgrass, sodgrass, shrub) is the primary factor influencing surface soil factors that control infiltration and erosion rates. On grass dominated landscapes the temporal response of surface soil factors induced by normal variations in climate, plant cover and biomass is greater than the spatial variability induced by grass growth form. To improve the utility of models for use on rangeland we must fully recognize that the rangeland system is spatially and temporally influenced by the amount and growth form of native vegetation.