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Submitted to: Geological Society of America Meeting
Publication Type: Abstract Only Publication Acceptance Date: 9/30/2002 Publication Date: 3/5/2003 Citation: STOUT, J.E. 2003. INTERMITTENT WIMD EROSION ACTIVITY IN BURNED SEMIARID GRASSLAND(abs). 99th ANNUAL MEETING OF THE ASSOCIATION OF AMERICAN GEOGRAPHERS, NEW ORLEANS, LA. 2003. Interpretive Summary: Wind and fire have always played an important role in the formation and evolution of Southern High Plains. The uppermost soils were deposited by wind into grassland vegetation. Within the last century, however, most of the natural vegetation on the Southern High Plains has been replaced by an extensive patchwork of cropland and this transformation has contributed significantly to the massive dust storms that blow across this vast region. Federal conservation programs, such as the Conservation Reserve Program (CRP), have helped reduce the frequency and intensity of wind erosion events by providing financial incentives that allow farmers to return highly erodible cropland to native grass cover for periods of 10 years or more. Cropland replanted to grass no longer loses topsoil due to wind erosion and no longer fouls the air with windblown dust. Unfortunately, the benefits of grass cover are lost when occasional wildfires remove protective vegetation from CRP fields. After a fire, the underlying soil surface becomes exposed and susceptible to wind erosion until sufficient regrowth . The purpose of this study was to measure and quantify the time of recovery, the amount of erosion that occurs during the recovery period, and the level of vegetative cover required to stabilize the field following a wildfire Technical Abstract: On March 11, 2001, fire swept across a grass field west of Lubbock, Texas transforming an otherwise stable grassland surface into a highly erodible surface. The next day, researchers from the Lubbock office of the USDA-Agricultural Research Service installed a saltation sampler and a piezoelectric saltation sensor to record temporal variations in sediment transport due to wind. In addition, a 2-m tall meteorological tower was installed to monitor surface winds and other climatic factors that influence the wind erosion process and a dust sampling system was installed downwind of the site to monitor ambient dust levels. A continuous record of wind erosion activity was obtained at the site over a 4-month period as the surface recovered from a highly erodible condition to a fully vegetated and stable surface. The results suggest that the critical threshold of the field increased from less than 10 m/s to above 20 m/s in a three month period as the vegetative cover was reestablished. |
