Fire-Induced Changes of Soil Structure: Implications for Soil Hydraulic Properties and Coupled Erosion by Water and Wind

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RAPID: Fire-Induced Changes of Soil Structure: Implications for Soil Hydraulic Properties and Coupled Erosion by Water and WindDavid Shafer, Associate Research Professor, Division of Hydrologic Sciences, DRIMichael Young, Associate Research Professor, Division of Hydrologic Sciences, DRIDave DuBois, Associate Research Professor, Division of Atmospheric Sciences, DRIMarkus Berli, Assistant Research Professor, Division of Hydrologic Sciences, DRIScott Tyler, Research Professor, Department of Geological Sciences and Engineering, UNRThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Project Abstract: The Gleason Controlled Burn, to be conducted near Ely, Nevada, provides an opportunity to quantify the effects of fire on soil structure, and to test hypotheses on how fire-induced changes in soil structure can lead to coupled water and wind erosion by collecting data at the same locations prior to and after the burn. The burn will be conducted by the U.S. Bureau of Land Management in August 2009. Because the burn is a planned event, pre- and post-burn measurements can be conducted on pre-determined sites. The funding awarded by NSF, along with internal funds from DRI, will be used to collect a set of pre-fire measurements. The area to be burned in the Gleason Fire has strongly-developed, coarse crumbled, soil structure in unburned areas. However, where other controlled burns have been done nearby, this structure has collapsed into a structureless soil, rich in fine particles that are most likely prone to erosion. Pre-fire measurements will include soil morphology and structure, water infiltration, air permeability, and wind-shear required to induce aeolian transport of soil particles. Hypotheses include: 1) the fire will destroy soil structure, increasing soil bulk density, and decreasing soil hydraulic conductivity and air permeability, a set of conditions that would increase the potential for soil erosion by water due to precipitation input; and, 2) the loss of soil structure will disaggregate soil material that would be more prone to suspension by wind at lower wind velocities, when compared to pre-burn conditions. Most studies on post-fire effects lack a true comparison to pre-fire conditions. This research will allow changes in soil structure to be quantitatively described and linked to post-fire hydraulic and aeolian transport properties that strongly influence the susceptibility of post-fire soil erosion. Although limited in scope, this research will provide the data needed for post-fire comparisons, and allow testing of some of the field and laboratory methods that the researchers will propose to use in a more comprehensive proposal to NSF on pre- and post-fire soil properties and erosion potential. The follow-on proposal will include collection of post-fire data from the Gleason Fire.