Drivers of wildfire spatial expansion: Modeling insights from semi-arid oak forests of W Iran

Wildfires are becoming increasingly recurrent in Iran, threatening vulnerable ecosystems, particularly the non-fire-adapted semi-arid oak forests in the western regions. This study investigates the environmental drivers influencing wildfire size in these forests, focusing on the years 2018–2020. To analyze the environmental drivers, a circular buffer of 314 ha was applied around each wildfire location, enabling the collection of predictive variables through remote sensing and in-situ measurements across three categories: topography, climate, and vegetation. Employing a non-linear Generalized Additive Model (R² = 0.822, explained deviance = 75.9 %), Land Surface Temperature (LST) emerged as the most significant factor in determining wildfire size, exhibiting a robust correlation with larger and faster-spreading fires. Furthermore, steep slopes and high-speed winds were associated with larger wildfires, enabling rapid fire spread and upslope progression. Wildfires were largest in areas with spatially consistent vegetation cover and peaked in April and May due to warmer temperatures and lower humidity. These findings underscore the need for the development of more proactive, adaptive, and effective strategies, ultimately reducing the toll of the destructive impacts on the integrity of these forests.