Climate-driven past fires in central Sicily

Wildfires in the Mediterranean basin are very important even if their causes and dynamics are not always fully understood. Fire occurrence is driven by several factors, such as the availability of fuel and the amount of biomass. In the Mediterranean basin, the seasonality of climate and its influence on vegetation plays an important role on flammability. Short-term fire dynamics and its relationship with vegetation is the subject of many present-day studies from local to global scales. Long-term fire dynamics can be investigated studying the residues of past plant burnings, such as microcharcoals. Microcharcoals extracted from lacustrine sediments are considered as a fire proxy and pollen as the best one for palaeovegetation reconstruction. We use pollen and microscopic charcoal data from a well-known Holocene sediment record from Lago di Pergusa (Sicily) to analyse their long-term relationships and to gain insights into environmental versus human-induced changes of fire behaviour. At a local scale, the fuel for wildfire is mainly provided by deciduous oaks. On the contrary, irrespective of the regional or local scale of analysis, Mediterranean vegetation seems not particularly fire-prone. Our data show that the largest fires occurred when the precipitation amount in the study area was sufficiently high to allow the development of all vegetation belts, from the Mediterranean to the montane one. Even if no doubt is left on the role of anthropogenic pressure in Sicily in the last few millennia, nonetheless our data highlight the relevant role of climate forcing on wildfires, which is mainly related to regional forest cover and, hence, to biomass and fuel availability.