2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 7
Presentation Time: 8:00 AM-6:00 PM

Pore Morphology of Vesicular Horizons Following Disturbance and Reformation in the Field

YONOVITZ, Maureen, Geoscience, University of Nevada Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154 and DROHAN, Patrick, Department of Crop and Soil Sciences, The Pennsylvania State University, 116 ASI Bldg, University Park, PA 16802, m5yr4_3@hotmail.com

Increasing desertification and anthropogenic soil disturbance is of growing concern to restoration ecologists in the Southwestern United States. This study examines how a common soil horizon of arid lands, the vesicular horizon, which is characterized by its discontinuous pores, responds to disturbance. The vesicular horizon is a near surface soil horizon typically composed of fine grained windblown material found beneath a desert pavement. Disturbance to the vesicular horizon may result in a change in pore morphology that will alter water movement through the horizon, affecting the ecology of the region. This research examines differences in pore morphology (area, perimeter, length and width), particle size, pH, calcium carbonate content (CCE) and conductivity (EC) between disturbed and undisturbed soils. Results indicate no significant difference in vesicle pore size with disturbance. Analyses of pore shape do indicate differences in types of pores formed; the percentage of pores with vesicular shape decrease while interstitial (irregular, between grains) shaped pores increase with disturbance. An increase in interstitial pores may result in more facilitated water movement to lower horizons than there would be in a soil with discontinuous vesicular pores, which could affect the vegetation growing in these areas. The re-formation of vesicular horizon porosity in a disturbed soil may be related to its prior (undisturbed) physical and chemical characteristics. This study is the first to document the morphology of pores that have been re-formed following disturbance in the field.