Are wildfires knocking on the built-up areas door?

Human-started fires represent the vast majority of wildfires in Mediterranean countries. The current expansion of human settlements into fire-prone territories has led to the creation of landscapes where anthropogenic developments merge with wildland areas. In this context, understanding the role of distance from built-up areas in shaping coarse-scale wildfire spatial patterns is a major concern. Proximity to cities has become an important factor that may increase the probability of wildfires in wildland-urban interfaces. To this issue, we developed an assessment of wildfire distribution in Italy over an 8-year period (2007-2014) to quantify fire occurrence and recurrence as a function of distance from built-up areas. Our findings suggest a positive relationship between the distance from built-up areas and fire incidence (i.e., ratio between burnt forest area and total forest area), whereas a negative relation was found between distance from built-up areas and fire frequency and recurrence; thus, there are more recurring yet smaller sized-fires near built-up areas. Fifty percent of fire events and more than two-thirds of recurrent fires occur within 200 m from built-up areas. On the other hand, the considerable amount of such fire events never reaches an incidence higher than 10% in flat areas and 30% in hilly and mountainous areas. More broadly, quantitative knowledge about where fires occur is essential to ensure appropriate fire management throughout large territories. With this in mind, our investigation intends to provide a solid base for further studies in landscapes with a high component of human-dominated land use.