Changing large wildfire dynamics in the wildland-urban interface of the eastern United States

Background 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 eastern US, the wildland-urban interface (WUI), where wildfire risk is greatest, has expanded tremendously over the last three decades. Aims This study aimed to understand how increasing wildfires in the eastern US are manifesting in the WUI. Methods We quantified WUI growth and characterised large (>200 ha) wildfire regimes inside and outside the WUI at multiple spatial scales across the eastern US between 1986 and 2021. Key results WUI wildfires in the eastern US 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 number and area burned occurred outside of the WUI. Conclusion The WUI plays an important role in large wildfire dynamics in the eastern US; however, increases in the number of large wildfires have occurred primarily outside the WUI. Implications Our findings highlight important interactions between human development and large wildfire occurrence in the eastern US and should be used to direct future region-specific assessments of changing wildfire risk.