DIATOM AND POLLEN EVIDENCE OF HOLOCENE VEGETATION DYNAMICS AND HUMAN IMPACT ON THE VIRENNES FENLAND (FRENCH MASSIF CENTRAL)

Abstract

The main focus of this study is the effect of human activities on paleoenvironmental changes in the Virennes fens during and after the Neolithic Period as indicated by diatoms and pollen. The site, located in the Livradois Mountains, was selected because of its location within the upper catchment of the Loire Valley, where forests were common before the arrival of the first farmers. Human activity in the area dates back to the fourth or third millennium BC. At first, humans seemed to be exploiting the wooded area as there are no signs of agriculture. Starting in the Iron Age and continuing into the Middle Ages, deforestation occurred in several steps as human populations expanded agricultural activity. It was only during the Iron Age that diatoms started being preserved in the fen. This corresponded to a period of increasing moisture in the fen. At the end of the Middle Ages, the forest expanded, agriculture almost disappeared from the area and maximum water depth was recorded in the fen. During the Modern Time, a cyclic pattern of agricultural expansion and deforestation followed by reforestation and reduction in agricultural land-use was observed. Recently, the area has been converted to pasture lands while fields have been replanted with fir and beech.

Key words:

• fen lands
• human impact
• diatoms
• pollen
• paleoecology
• Massif Central