Altitudinal evolution of vegetation on the Vercors Massif since the Late Glacial Period: new pollen data from Combe‑Chevalière (Chichilianne, Isère, 1,650 m)

The Combe Chevalière provided an interesting sequence for reconstructing the subalpine vegetation over the last 18,000 years. This sequence, derived from a wetland area and documented in parallel with a sedimentological study, is subject to periods of low water input that lead to the drying of the area and, consequently, low or no sedimentation, as well as poorer preservation of pollen assemblages compared to other sediment types. The studied sequence is therefore incomplete, and despite a sedimentary hiatus at the Preboreal level, it still provides insight into the vegetation dynamics near the study area, at the subalpine level, as well as at the upper limit of the montane zone. Since Combe Chevalière is bordered by areas of Mesolithic occupations, this study provides an environmental context for these sites. The palynological analysis of Combe Chevalière follows numerous other studies conducted at different vegetation levels, thus contributing to a broader analysis of vegetation evolution within the Vercors Massif. The vege- tation evolution is consistent with the various vegetation zones. Late-glacial climatic variations are characterized by oscillations of Pinus, Betula, and Juniperus in the hill and montane zones, while the more rigorous climate of the subalpine zone is dominated by herbaceous plants. Pinus and deciduous trees were present in the sub-alpine zone since 9,000 years ago (cal. BP), and were replaced by herbaceous and Picea during the Subboreal. Competition with Abies, recorded since 7,800 cal. BP, seems to be the cause of the decrease in this taxon from the Subatlantic period onwards. Human impact also varies with altitude. In the hill zone, Juglans, Castanea, and Populus were cultivated during the Subatlantic period, while at the same time, in the montane zone, human activity is reflected in the forest exploitation of Abies.