Regional fire history shows abrupt responses of Mediterranean ecosystems to centennial-scale climate change ( Olea–Pistacia woodlands, NE Morocco)

Abstract

The reconstruction of regional fire history with the aid of a sedimentary charcoal record (1.4–4.0 ka cal BP) of semiarid Pistacia and Olea woodlands from NE Morocco demonstrates a high sensitivity of desert margins in the SW Mediterranean towards Rapid Climate Changes. The sedimentary charcoal record derives from alluvial archives of the Lower Moulouya River. These archives contain a centennial-scale proxy record for Mid- to Late Holocene fire histories. We analyse the charcoal data together with proxy data from the same record (palaeomagnetics, anthracological and snail analyses, palaeoflood chronology) to determine palaeoenvironmental conditions. The environmental history of the SW Mediterranean is discussed with respect to our data, and in the context of other regional palaeoenvironmental archives. We demonstrate a strong coupling of charcoal accumulation with Holocene Rapid Climate Changes. We deduce low charcoal densities and pronounced Lower Moulouya flood events in the course of Holocene cooling between 2.7 and 3.2 ka cal BP, and interpret them carefully as a fuel load limited ecosystem during a regional phase of aridity with lower mean annual rainfall but more intense precipitation patterns.