Inferring the ancientness of the Mirambel woodland from soil charcoal: A local exception to the regional pattern of the Millevaches plateau (Limousin, Massif Central, France)

摘要

The Mirambel woodland on the margins of the Millevaches plateau (Massif Central) is one of the few ancient broad-leaved woodlands in France. Historical sources show that it has occupied the same surface area for the past 250 years, despite being in a region that underwent considerable anthropogenic changes during this period. We explored the Mirambel's Holocene history and ancientness by means of soil charcoal analysis, chosen because of its high accuracy on a local scale. We excavated five pedoanthracological pits in the woodland and its open marginal spaces. The 29 radiocarbon dates ranged from the Atlantic (8700-5500 cal yr BP) - Subboreal tran-sition to the Subboreal (5500-2800 cal yr BP) and Subatlantic (2800-0 cal yr BP, i.e. AD 1950) periods, revealing the existence of fire events corresponding to six contemporaneous cultural periods: Neolithic (ca. 3877-2991 cal yr BC), Neolithic-Chalcolithic transition (ca. 2528-2525 cal yr BC), Protohistory (ca. 147 cal yr BC), Roman period (AD 326-579), Middle Ages (AD 732-1187), and contemporary times (AD 1781 to present day). Three Tilia charcoal fragments dating from ca. 3717-2919 cal yr BC indicated the presence of a diversified Mid-Holocene deciduous woodland featuring Tilia and Acer nowadays-absent taxa in this area. Deciduous Quercus and Fagus sylvatica dominated most of the soil profiles, as they do nowadays in the woodlands. Other taxa (Salix, Corylus avellana, Betula) were identified, as well as in the current vegetation. The occurrence of Cytisus-type (Fabaceae) and Calluna vulgaris suggested that there were forest clearing phases at all the points sampled. Widely varying levels of abundances may reflect differences in the duration of these open phases.