Paleofire dynamics in Central Spain during the Late Holocene: the role of climatic and anthropogenic forcing

The use of fire and, consequently, its severity and incidence on the environment have grown steadily during the last millennia throughout the Mediterranean. This issue can be assessed in several mountain ranges of central Iberia where changes in the management policy on anthropic activities and exploitation of high-mountain environments have promoted a remarkable increase on fire frequency. Our research focuses on fire dynamics throughout the last 3,000 years from three peat bog charcoal records of the Gredos range (central Iberia). Our aim is to reconstruct past fire regimes according to forest vegetation typology (Castanea sativa, Pinus pinaster, and Pinus sylvestris). Charcoal influx shows low values between 3,140 and 1,800 cal. year BP when forests were relatively dense in both high and mid-mountain areas. Fire appeared synchronous between 1,800 and 1,700 cal. year BP for Lanzahíta and Serranillos and around 1,400–1,240 cal. year BP for the three sites, suggesting anthropogenic fire control between the Late Roman and Visigothic periods that can be related to the cultivation of olive trees in the valleys and a greater human impact in high-mountain areas. By contrast, during the Muslim period (1,240–850 cal. year BP), fire dynamics becomes asynchronous. Later, fires turn again coeval in the Gredos range during the Christian period (850–500 cal. year BP) and can be also correlated with drought phases during the Late Medieval Warm Episode. In short, our study demonstrates that fire activity has been enormously variable during the late Holocene in response to both short-term and long-term regional and global climate, vegetation dynamics, and land use changes.