Environmental changes over the past 25 000 years in the southern Middle Atlas, Morocco

International audienceA new fossil record from the southern Middle Atlas spans continuously the last 25000 years and provides evidence of an increased amount of snow precipitation during the last glacial period and a warm early Holocene with rather dry climate conditions. This environmental reconstruction is based on a multi-proxy approach that integrates pollen, micro-charcoals, grain size and geochemical analysis. During the last glacial period we observe a strong presence of aquatic plants species that today flower during late spring and summer. These occurrences are related to an increased amount of snow precipitation on the surrounding mountains which fed the marsh during the summer season. Although the early Holocene reveals a slight and steady expansion of Mediterranean oaks, the semi-arid Artemisia steppe remained dominant in the landscape until 6.8ka cal BP. Thus, the early Holocene seems to have been less humid than elsewhere in North Africa. The Atlas cedars began to establish around 6ka cal BP. This indicates that the amount of annual rainfall increased after the mid-Holocene. The late Holocene is marked by an increase of fire events, which may be related to a strengthening of the dry season and/or a higher seasonality. Copyright (C) 2016 John Wiley & Sons, Ltd