Forest fires in the wildland-urban interface: A spatial analysis of forest fragmentation and human impacts

The contact zone between human infrastructure and wildland vegetation, known as the wildland-urban interface (WUI), has increased worldwide over the last decades and has a direct relationship with the risk of forest fires. Human activities increase the likelihood of wildfires, which can have disastrous consequences for property and land use and can pose a serious threat to lives. This paper examines the spatial patterns of the WUI and wildfire ignition points in Galicia (NW, Spain). We spatially delimited and classified WUI areas by the intensity of human presence, using the spatial arrangement of buildings. We also classified the areas by forest fragmentation and then explored the statistical differences in the density of forest-fire ignitions among areas in the different WUI categories. The study area in Galicia has the highest rate of wildfire incidents in Spain. Our results show that more than half of the built area is located in the WUI and that fire ignition is approximately twice as frequent in WUI as in non-WUI areas. The highest wildfire occurrence is in unforested areas of the WUI, while the lowest fire density is associated with isolated buildings. Areas with very dense clusters of buildings surrounded by forestland, characterized here as peri-urban areas, have the highest density of fire ignition. This trend highlights the vulnerability of the interface to fire in this region. Particularly in high risk areas, our work can advance spatial delimitation policies and further the development and promotion of plans for the protection of human lives, property and economic activity.