Date of Award

9-2023

Degree Name

MS in Environmental Sciences and Management

Department

Natural Resources Management

College

College of Agriculture, Food, and Environmental Sciences

Advisor

Stewart Wilson

Advisor 2

Yamina Pressler

Advisor Department

Natural Resources Management

Advisor College

College of Agriculture, Food, and Environmental Sciences

Abstract

In the past few decades, the world’s climate is being altered by anthropogenic forces such as the increase in carbon dioxide (CO2) emissions due to fossil fuel combustion (Paraschiv and Paraschiv, 2020). In California, the impacts of increased CO2 concentrations have created longer fire seasons, warmer temperatures, and increased lightning strikes which allow for wildfires to become more frequent, severe, and larger in scale (Westerling et al., 2006). Wildfires of this magnitude result in acceleration of landscape scale processes such as erosion and aggregation which in turn affects soil organic matter (SOM), the basis of soil health (Gonz´alez-P´erez et al., 2004). This project is intended to close the knowledge gap and broaden our understanding of the impacts of burn severity on SOM partitioning at the watershed scale in California. To accomplish this, soil samples were first collected one year following the CZU Lightning Complex Fire at Swanton Pacific Ranch. The samples were separated into particulate organic matter (POM) and mineral-associated organic matter (MAOM), analyzed for carbon (C) and nitrogen (N) content, and then their stock was compared to burn severity and other environmental covariates. The environmental covariates were derived from geospatial data corresponding to the soil forming factors and burn severity to understand the watershed scale controls on SOM fractions. Spatial data included remote sensing data corresponding to terrain, climate, vegetation, lithology, and fire variables. Through analysis, Difference Normalized Burn Ratio (dNBR), climate data, and terrain data were the most dominant predictors of MAOM and POM C and N. Ultimately, this research will allow for greater understanding of landscape-scale SOM partitioning and soil quality post-fire.

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