RAPID: Evaluation of post-wildfire effects on soil physical and chemical properties in response to the Caldor and Tamarack fires near Lake Tahoe

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Wildfire-induced changes to soil properties impact infiltration, runoff, and soil erodibility in fire-prone areas. Recent wildfires in the eastern Sierra Nevada mountains provide a unique opportunity to quantify fire effects on soil properties in natural field settings. These wildfires represent a new generation of large high-temperature canopy fires that are likely to increase in frequency in this region due to changing climate. Reduced infiltration and enhanced runoff after fire are directly related to changes in the structure and surface chemistry of the pore system within the soil. Fire effects on soil physical and chemical properties have been quantified mostly in the laboratory but not in natural field settings. This project will quantify the effect of two large wildfires (Caldor and Tamarack) on soil physical and chemical properties to better understand how fires affect hillslope hydrologic processes (infiltration, runoff, erosion), fire-related secondary risks such as flooding and debris flows, and forest management practices related to fire activity.This project will quantify post-fire changes to soil physical and chemical properties to better understand their impact on post-fire runoff, infiltration, and erosion in natural settings. Samples will be collected from burned and unburned locations both to measure soil hydraulic and thermal conductivity functions via controlled evaporation experiments and to identify functional groups in soil organic matter that influence soil hydrophobicity using proton nuclear magnetic resonance spectrometry. Additionally, infiltration and soil hydrophobicity will be measured in-situ using infiltrometer tests. Results will be presented to local stakeholders of fire-prone watersheds to guide forest management and improve the sustainability of water and ecosystem resources. Results will be transferable to watersheds in the Sierra Nevada with similar soil conditions. This project will provide research opportunities for an early career scientist, field training to a Ph.D. student, and hands-on experience for an undergraduate student.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.