Pore morphology characteristics of vesicular horizons in undisturbed and disturbed arid soils; implications for arid land management

We compared the pore morphology of an arid lands vesicular soil horizon in a disturbed and undisturbed state. This surface vesicular horizon is characterized by non-connected pores that hinder soil water infiltration and thus plays a central role in arid ecosystem hydrodynamics. Disturbance is hypothesized to result in a change in pore morphology that could alter water movement through the horizon and potentially affect ecosystem function. To test this hypothesis, we examined the pore morphology of the vesicular horizon as expressed in area, perimeter, length and width; comparisons were also made for particle size, pH, calcium carbonate equivalent (CCE), electrical conductivity (EC) and the abundance and types of pores in undisturbed soils and adjacent disturbed soils within a year of disturbance. The results indicate no significant differences between treatments in chemistry, particle size or pore morphological measures within a year following disturbance. Vesicles, vughs and interstitial pores were found in vesicular horizons in both treatments and no significant differences in these parameters were found between treatments. Vesicular horizon development may be related to the geological age of the surface materials. Certain old land surfaces are perhaps more susceptible to the formation of vesicular horizons regardless of disturbance. The results suggest that soil functions dependent upon vesicular porosity, for example hydraulic conductivity, may return to a pre-disturbance condition within one year of disturbance, a finding of importance to the management of arid lands.