Évolution de la végétation du massif du Morvan (Bourgogne - France) depuis la dernière glaciation à partir de l'analyse pollinique. Variations climatiques et impact des activités anthropiques

摘要

This PhD thesis aims at documenting the vegetation history of the granitic middle mountain of Morvan (France), in connection with climate change and human impact. The study is based on ten peat cores, on which pollen analyses were performed including non-pollen palynomorphs (NPPs). The records about vegetation dynamics are incomplete for the Lateglacial, but they well highlight the history of Holocene forest dynamics. They also reveal regional particularities, such as the low occurrence of conifers in the Morvan's forest before the 20th century (human introduction). To document the history of human activities at a regional scale, a particular attention has been paid to the determination and the characterisation of human impact phases. In this context, the study also benefited, for some sites, from the contribution of other proxies such as charcoals, sedimentology and isotopic geochemistry documenting atmospheric palaeopollutions. These analyses renew human history of this middle mountain area. They reveal a clear human presence during period that were formely poorly documented, such as Early Neolithic (5000-4500 cal BC), first Iron Age (800-450 cal BC), Early Middle Ages (from 5th/6th centuries). The palaeoecological data also bring new lights over periods for which there is a better archaeological and historical knowledge. For example, they illustrated the attractive role of the mining resources at least from the end of Late Bronze Age (ca. 1650 cal BC), and especially at the time of the Eduean oppidum of Bibracte on the Mont-Beuvray (2nd and 1st century cal BC).