Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2002
Publication Date: 9/1/2003
Citation: NASH,M.S., JACKSON,E., WHITFORD,W.G. SOIL MICROTOPOGRAPHY ON GRAZING GRADIENTS IN CHIHUAHUAN DESERT GRASSLANDS. JOURNAL OF ARID ENVIRONMENTS. 2003. V. 55(1). P. 181-192. Interpretive Summary: This study examined the effects of concentration of livestock activity at water points in a hot arid environment. In native black-grama grassland, grass tussocks form on small mounds separated from each other by slight depressions of bare soil. Concentrations of livestock at water points eliminate most of the grass, flatten the mounds, and fill in the depressions. The resulting loss of surface roughness exposes the area nearest water points to increased probability of wind erosion. Loss of surface materials by wind erosion increases the difficulty of reversing the degradation and returning the area to productivity
Technical Abstract: The significant impacts of livestock in the creation of piospheres centered on water points is the loss of soil microtopography across a `landscape' that has been influenced by many years of livestock grazing. The size, height, and spatial distribution of micromounds and surrounding depressions were measured by a modified erosion bridge at three distances (50, 450, and 1050 m) from water points in desert grassland pastures in the Jornada Basin, New Mexico, USA. Plots at 50m had fewer micromounds and the mounds were smaller than those recorded on the more distant plots. Microtopography of plots at 450m from water was not significantly different from that recorded at 50m. Microtopography of plots that were 1050m from water points was significantly different from that of plots nearer water points. Strong correlation between microtopography and the cover of long-lived perennial grasses (R2=91%) was found, such dependence could be used for assessing the trend in organic matter content that is in concordance with that of microtopography. Loss of microtopography from the impact of livestock in piospheres exacerbates erosion processes and contributes to desertification.