Abstract
Anthropogenic climate change is increasing wildfire activity in much of the Western United States. Wildfires are burning more frequently and larger than historical fire regimes. Historical fire suppression has led to an overaccumulation of heavy fuels. This overaccumulation of fuels coupled with increased warming has exacerbated the conditions for high severity fire. Burn severity is a postfire quantification of the ecological effects of a wildfire. Burn severity is classified into three main categories: high, moderate, and low. California's seasonallydryforests,which historically had a frequent, mixed severity fire regime is now seeing increased high severity burns. High severity, or stand replacing fire, can have negative ecological consequences such as habitat loss, increased erosion potential, and increased emissions. Previous work has used statistical models of fire occurrence and fire size to project the impacts of the changing climate on fuels and future fire, however there is currently a gap in modeling for burn severity. By jointly modeling all three burn severity classifications we can also observed how fire severity impacts ecosystems, risks, and loss. This dissertation is comprised of three projects that develop statistical techniques for estimating, simulating, and projecting burn severity across multiple spatial scales. We find that drought driven dead fuel accumulations and increased aridity are the main causes of increased burn severity. Adequate reductions of fuels can increase moderate and low severity fire which promotes ecosystem health and resilience.

Biography

Jonathan has been a UC Merced Bobcat for nearly a decade, where he received his Bachelor’s in Earth Systems Science and is currently a PhD Candidate in the Environmental Systems group. He joinedProfessor LeRoy Westerling’slab in 2018 focusing his work on wildfire burn severity and climate change.  Jonathan now works as a Climate Change Scientist at CoreLogic Inc working on risk and catastrophe modeling. In his free time, Jonathan enjoys fishing, hiking, and kayaking.