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

Dr. Stewart Wilson

Advisor 2

Dr. Yamina Pressler

Advisor Department

Natural Resources Management

Advisor College

College of Agriculture, Food, and Environmental Sciences

Abstract

Wildfires have increased in frequency and severity over the past few decades due to the increased concertation of CO2 emissions from anthropogenic influence. Soil carbon (C) sequestration has been identified as a climate change mitigation strategy; however, the influx of large-scale wildfires has accelerated landscape processes such as erosion, reducing soil aggradation, and soil C and nitrogen (N) protection. This trend is highlighted by the Creek Fire that occurred in September 2020 and burned 379,895 acres in the Sierra National Forest. This research is designed to close the knowledge gap regarding the impact of burn severity on soil organic matter (SOM) C and N distribution at the landscape scale in California. To accomplish this, 70 soil samples were collected two years following the Creek Fire at a depth of 0-5 cm. These SOM samples were separated into mineral-associated organic matter (MAOM) and particulate organic matter (POM) to better understand how these size fractions influence soil C and N stocks. Alone burn severity is not statistically significant; however, the multiple variable regression analysis shows that Landsat dNBR burn severity is a significant predictor variable for all MAOM-C, MAOM-N, POM-C, and POM-N when coupled with other predictor variables. Additional predictor variables with significance include lithology variables, vegetation variables such as moisture and total greenness, and topography variables such as elevation and roughness. The POM-N model was the best at depicting SOM relationships, by explaining 48% of the variance in POM-N; therefore, a predictive map was created to depict this relationship. The results of this study provide valuable information and context regarding post-fire SOM C and N storage and can be used to inform future management decisions involving landscape restoration.

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