Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2012
Publication Date: July 1, 2012
Citation: Stout, J.E. 2012. A field study of wind erosion following a grass fire on the Llano Estacado of North America. Journal of Arid Environments. 82(3):165-174. Interpretive Summary: The Conservation Reserve Program provides financial incentives for farmers to return highly erodible cropland to native grass cover for periods of ten to fifteen years. Grass cover stabilizes the surface by preventing soils from becoming detached and deflated by strong winds. When occasional grassfires remove protective vegetation, wind erosion can occur as the surface slowly recovers. Threshold is an important parameter in this regard since the removal of protective vegetation lowers the wind speed necessary to erode the soil surface. Recently, a new technique was developed that provides a practical method for establishing the critical threshold of an erodible surface using a sampling system that continuously collects wind data along with critical information regarding wind erosion activity. Here this method was used to measure temporal changes in the threshold of the recovering surface. Results suggest that the threshold of the field increased from less than 10 m/s immediately following the fire to above 19 m/s in a six-month period as vegetation naturally recovered.
Technical Abstract: Interactions between earth, wind and fire have played an important role in the formation and evolution of the level plains of the Llano Estacado of North America. The uppermost sediments of this vast region are aeolian deposits stabilized by grassland vegetation. Grass cover enhances aeolian deposition by slowing near-surface winds and vegetation secures sediments once they are deposited. The benefits of grass cover, however, are lost when occasional wildfires remove protective vegetation from fields. After a fire, the underlying soil surface becomes exposed and susceptible to wind erosion until the vegetative cover is reestablished. The purpose of this study was to explore the post-fire recovery process by monitoring temporal variations in aeolian transport and measuring changes in threshold velocity of a burned grass field located in Lubbock County, Texas. A continuous record of wind erosion activity was obtained at the site during a six-month period as the surface recovered from a highly erodible state to a fully vegetated and stable surface. Results suggest that the threshold of the field increased from less than 10 m/s immediately following the fire to above 19 m/s in a six-month period as vegetation naturally recovered.