ARS | Publication request: On the effect of fires on aeolian processes in dryland landscapes

Submitted to: International Conference on Aeolian Research
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 2010
Publication Date: July 9, 2010
Citation: Ravi, S., D'Odorico, P., Zobeck, T.M., Over, T.M. 2010. On the effect of fires on aeolian processes in dryland landscapes[abstract]. International Conference on Aeolian Research. July 5-9, 2010, Santa Rosa, La Pampa, Argentina. p. 55.

Technical Abstract: The occurrence of fire and the subsequent increase in wind erosion are known to affect the dynamics of dryland landscapes. Fires act as a disturbance on vegetation and expose the soil surface to the erosive action of wind, thereby affecting the loss and redistribution of soil nutrients. The positive feedback inherent to the removal of nutrient-rich soil from the barren areas and to its deposition onto vegetated patches contributes to the formation of heterogeneous landscapes with shrub-dominated areas surrounded by barren areas. Despite the relevance of wind erosion and fires to the dynamics of arid ecosystems, the interactions between these two processes remain poorly understood. Recent experimental evidence suggests that the erodibility of burned areas is significantly higher than that of adjacent bare unburned soil and that this difference significantly affects the redistribution of nutrient-rich soil particles across the landscape. However, most of the existing studies on the impact of fires on soil erodibility has been traditionally confined to the obvious ability of fires to degrade the vegetation cover thereby depriving the soil surface of the sheltering effect of grass and shrub vegetation. Here we explain these experimental findings as an effect of fire-induced soil water repellency. To this end, we test the hypothesis that by affecting the strength of interparticle bonding forces, fire-induced water repellency enhances soil erodibility, causing a drop in wind erosion threshold velocity (i.e., the minimum velocity for erosion to occur). We use a set of laboratory, field, and modeling methods to show how the postfire enhancement of soil erodibility is an effect of the weakening of interparticle bonding forces resulting from the development of soil hydrophobicity.