V for Volatile: VOCs and the venture of upscaling flammability in the wildland urban interface

Wildfire risk assessments (WRAs) are crucial to protect residents in fire-prone wildland-urban interfaces (WUIs). While WRAs primarily rely on water content and weather patterns, previous studies have demonstrated that additional plant traits including foliar chemistry contribute to plant flammability. Various plant species native to the Southern California WUI store volatile organic compounds (VOCs). We tested how heat and drought stress influenced VOC dynamics in a growth chamber experiment. To determine relative effects of VOC content on flammability, we compared plant flammability to a suite of traits across species sampled from the nearby WUI. We found variable relationships with drought and heat stress and VOC content in S. mellifera and that plant flammability was associated with water content, foliar chemistry, branch morphology, and leaf morphology. These findings address a critical gap in scaling tissue-level flammability to WRAs and inform fire-safe landscaping in the WUI.