Srikantnag Angondalli Nagaraja , Dorottya Fuzy, Istvan Kereszy, John Kern, Chang Zhao, Imre Bartos

Between 2001 and 2023, wildfires in the Wildland Urban Interface (WUI) caused by power lines, vehicles, and equipment accounted for approximately 23% of the total area burned by identified ignition sources, burning an estimated 3 million acres in California alone. These ignition sources have been major contributors to the destruction of infrastructure, loss of life, and air pollution in WUI areas. The invasive grass species Bromus tectorum (cheatgrass) has played a significant role in accelerating the spread of fire. Here we demonstrate the connection between the presence of cheatgrass and wildfires of different causes. We find that in California in 2023, cheatgrass covered close to 60% of the area burned for both powerline and roadside wildfires, despite covering less than 15% of California. We also identify the presence of cheatgrass near the ignition sites of some recent major California wildfires, including the 2018 Camp Fire and the 2024 Park Fire. We present detailed 10-meter resolution maps of California identifying powerlines and roads surrounded by cheatgrass. Our findings highlight the critical importance of vegetation management in ignition hotspots to mitigate wildfire risks in the WUI.