Disentangling the factors of spatio-temporal patterns of wildfire activity in south-eastern France

Abstract

Background. Identifying if and how climatic and non-climatic factors drive local changes in fire regimes is, as in many other human-dominated landscapes, challenging in south-eastern France where both heterogeneous spatial patterns and complex fire trends are observed. Aim. We sought to identify the factors driving the spatial-temporal patterns of fire activity in southeastern France. Methods. We incorporated several non-climatic variables into the probabilistic Firelihood model of fire activity and implemented an enhanced spatio-temporal component to quantitatively assess remaining unexplained variations in fire activity. Key results. Several non-climatic drivers (i.e. orography, land cover and human activities) contributed as much as fire-weather to the distribution of fire occurrence (>1 ha) but less to larger fires (>10, 100 and 1000 ha). Over the past decades, increased fire-weather induced a strong increase in wildfire probabilities, which was actually observed on the western part of the region but not so in the east and Corsican Island, most likely due to reinforced suppression policies. Conclusions. While spatial patterns in fire activity are driven by land-use and land-cover factors, temporal patterns were mostly driven by changes in fire-weather and unexplained effects potentially related to suppression policies but with large differences between regions.

Mapping territorial vulnerability to wildfires: A participative multi-criteria analysis

“…Over the decades to come, fire danger is expected to increase significantly owing to increases in temperatures and changes in precipitation patterns (Dupuy et al, 2020;Fargeon et al, 2020). Climate change could induce an increase in the number of large fires (>100ha) by up to +180% for a +4°C warming, a doubling of fire-prone areas and a large symmetrical lengthening of the summer fire season (Pimont et al 2022).…”

“…erosion and flood control), as well as aesthetic and cultural services due to touristic frequentation, which is very high in the summer along the coast and in the mountains. These Land-Use and Land-Cover factors affect spatial patterns of fire activity (Castel-Clavera et al, 2022).…”

“…wildfires are known to be prevalent in locations with high wildland-urban interface (Radeloff et al, 2018). As a result, there is a need to discuss and prepare fire risk management policy locally with stakeholders, especially in regions where wildfire regimes are expected to worsen, such as the Mediterranean (Dupuy et al, 2020;Pimont et al, 2022).…”

“…This approach of vulnerability is furthermore combined with probabilistic modelling of fire activity (Pimont et al 2021) to assess fire hazard, hence resulting in an integrated multidisciplinary approach to wildfire risk. We focus on South-Eastern France, a fire prone area with contrasted land-use patterns which influence fire activities (Castel-Clavera et al, 2022) and where fire regimes are expected to worsen through significant intensification of fire activities, an expansion of the fire-prone region and a lengthening of the summer fire season (Pimont et al 2022).…”

IX International Conference on Forest Fire Research and 17th International Wildland Fire Safety Summit: introduction to special issue (Part 1)

“…Using projections of future fire activity in southeastern France the authors project that very large increases in fire activity would arise mostly from an intensification within the already fire-prone region and during the core of the current fire season rather than from an expansion of the fire-prone region or from a lengthening of the fire season. Castel-Clavera et al (2023) attempt to disentangle the factors correlated with the spatiotemporal patterns of wildfire activity in southeastern France that were considered in the previous paper. They applied Bayesian models to separate the contributions of climatic and non-climatic drivers to fire activity in Mediterranean France.…”