Reconstruction and paleoclimatic interpretation of Holocene lake-level changes in Lac de Saint-Léger, Haute-Provence, southeast France

Abstract

Abstract Lac de Saint-Leger is located in the transitional region between Central Europe and the Mediterranean. The reconstruction of the past lake-level changes was based on plant macrofossil and mollusc analyses of two stratigraphic transects correlated by pollen analysis. Past changes in lake level were quantitatively reconstructed from changes in the recorded level of overgrowth. In the beginning of the Holocene the lake level was high; however, a progressive lowering occurred from about 7500 B.P. Between about 4500 B.P. and 4000 B.P. there was a moderate rise in lake level. Subsequently the lowering was continued and culminated between about 3300 B.P. and 2500 B.P. From the reconstruction there then occurred a progressive rise in lake level until the present. The lake-level changes recorded in Lac de Saint-Leger are compared with a compilation of lake-level data from southern France. The major long-term changes can be supposed to be regionally significant and related to climatic changes. To obtain a basis for paleoclimatic interpretation of the changes in lake level, the reference pollen diagram from Lac de Saint-Leger was used for a quantitative reconstruction of paleoclimate. During the middle and later part of the Holocene there is a reasonable consistency between the recorded pattern of lake-level changes and the paleoclimatic reconstruction. During the earlier part of the Holocene there are some disagreements, which may be explained by the shortage in adequate modern pollen analogues. The paleoclimatic reconstruction indicates that the major changes in lake level were mostly related to changes in precipitation.