Pyroclimatic classification of Mediterranean and mountain landscapes of south-eastern France

Abstract

Fire risk is expected to increase in the Mediterranean Basin like in many areas worldwide. Climate is likely the main driver of fire activity by conditioning fuel dryness and fire weather. However fire-climate relationships are conditioned by other environmental dimensions like fuel structure (composition and spatial arrangement of flammable vegetation) and human activities. Therefore assessing how climate controls fire activity in heavily anthropized landscapes like European Mediterranean regions requires to design analyses in appropriate geographic units to encompass the dominant fire drivers. We aimed to assess how spatiotemporal patterns of both fire activity and climate structured south-eastern France into homogeneous geographic unit which we defined as ‘pyroclimatic’ regions. We performed a pyroclimatic classification of Mediterranean and mountain areas of south-eastern France at 2 km resolution from the national fire database and daily atmospheric parameters over 1973-2009. This classification was based on multidimensional and clustering analyses. South-eastern France is characterized by three main ‘pyroclimatic’ regions and ten sub-regions from high fire-prone maritime mountains to moderate fire-prone hot lowlands and low fire-prone inner moist mountains. These geographic units are discriminated from each other by fire activity, fire seasonality, fire weather and their recent evolution. We demonstrated that fire activity and fire weather of south-eastern France are highly dynamic in space and time. Characterizing pyroclimatic regions offers new regional perspectives of fire management and policy because two areas having similar fire weather, fire regime and recent temporal trends would benefit for specific attention.