Rethinking lightning-induced fires: Spatial variability and implications for management policies

Lightning is the primary natural ignition source for wildfires. However, in certain ecosystems, anthropogenic fires predominate and account for the majority of fire incidents. In many countries, the prevailing perception holds that wildfires are overwhelmingly human-caused. While statistically accurate when pooling data from across the country, this perspective leads to a misconception that wildfires are not a natural component of ecosystems. This generalization requires a critical examination of regional variability in lightning-induced wildfires (LIWs). As a case study, we examined the spatial distribution of LIWs in Türkiye using national wildfire data between 2002 and 2022. We considered three main wildfire causes: human-caused, lightning-induced, and unknown-origin. We investigated the distribution of fire occurrences and burned areas to demonstrate the spatial variability of LIWs and human-caused fires (HCFs) across Türkiye at the regional and local forest management unit levels. We found considerable regional and local disparities in the incidence of LIWs across Türkiye. We also observed a higher incidence of LIWs in areas with higher lightning densities, especially in the mountainous regions of western and northern Anatolia, including southwestern and northwestern Anatolia. In certain years, the proportion of LIWs exceeds 45 % in some regional units and 75 % in many local units. However, LIWs burned significantly smaller areas than HCFs. The most populated regions primarily experienced HCFs, while in several other regions, including less-populated or forest-rich ones, lightning was a major source of wildfires. Seasonal trends also emerged, showing an increased prevalence of LIWs, with a peak during the fire season and a relatively higher percentage during seasonal transitions. Despite the increasing human activity, LIWs have remained a significant cause of wildfires in several regions in the country. Our results on the significant spatial variability in LIWs challenge the traditional belief that human activities are the primary ignition sources for wildfires across Türkiye and downplay lightning as an ignition source. Our findings suggest that a one-size-fits-all fire management strategy which has led to wildfire suppression policies for the past century is suboptimal for countries where lightning is a significant source of wildfires. Therefore, an ecologically sound and economically efficient wildfire management policy must account for regional variability in the causes of wildfires. Accordingly, we recommend a reassessment of blanket fire suppression strategy in several countries such as Türkiye, advocating for more selective suppression practices that consider the role of naturally occurring wildfires.