Patterns and drivers of large wildfires within and surrounding the wildland-urban interface of the eastern United States

The recent increase in large wildfires in the eastern United States makes it crucial to examine the subsequent risk to human life and property. In the East, thewildland-urban interface (WUI), where wildfire risk is greatest, has expanded tremendously over the last three decades. In this thesis, we aimed to understand how increasing large wildfires in the East are manifesting in the WUI. Using large (≥200 ha) wildfire perimeters, we (1) assessed WUI growth and its relationship with large wildfire regime characteristics and (2) determined the spatial WUI-wildfire relationships and the social and environmental factors driving these patterns over the last three decades in the eastern US at multiple spatial scales. While the WUI only makes up 22% of the East, WUI wildfires comprised 45% of all large wildfires and 55% of the area burned, were on average 46% larger than non-WUI wildfires, and are becoming more frequent in spring. Most increases in wildfire activity occurred outside of the WUI. Additionally, large wildfires burn less often in the WUI and less of the WUI than expected at random; however, wildfires that burn outside of the WUI burn closer to the WUI than expected. Environmental factors and, to a lesser extent, social variables are important for predicting these WUI-wildfire relationships. Higher levels of woody cover, drier conditions, and strained federal suppression resources drove wildfire occurrence in and near the WUI. Our findings highlight important interactions between human development and large wildfire occurrence and the need for proactive fuels management in the East.