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, has 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 three thousand 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, P. sylvestris). Charcoal influx shows low values between 3140 and 1800 cal. yr BP when forests were relatively dense both in high and mid-mountain areas. Fire appeared synchronous between 1800 and 1700 cal. yr BP for Lanzahita and Serranillos and around 1400-1240 cal. yr BP for the three sites suggesting anthropogenic fire control between the Late Roman and the 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 (1240-850 cal. yr BP) fire dynamics becomes asynchronous. Later, fires turn again coeval in the Gredos range during the Christian period (850-500 cal. yr 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- and long-term regional and global climate, vegetation dynamics and land use changes.