Holocene vegetation succession and forest history in the upper Monts du Forez, Massif Central, France

摘要

On the basis of seven palynological records, we reconstruct the forest-limit composition and dynamics during the second part of the Holocene, in the upper montane and subalpine zones of the Monts du Forez in the north-eastern Massif Central, using a 2 km long, elevational transect of sites at 1335-1590 m elevation. All sites are mires today, varying in size from 2 to <0.1 ha. The chronology of the pollen diagrams is based on calibrated radiocarbon dating combined with pollen-stratigraphic correlation among the diagrams using the regional pollen component. Corylus avellana forest with Ulmus developed in the study region soon after the start of the Holocene. Soon after Fagus sylvatica arrived in the study area and expanded after ca. 3500 BC (5450 cal yr BP) to full abundance within a few centuries at the cost of Corylus. Abies alba expanded slowly within the Fagus forest after ca. 3300 BC (5250 cal yr BP), taking two millennia to reach its final abundance. During ca. 800-650 BC (2750-2600 cal yr BP) Fagus and Abies had reached similar overall abundances and formed forests only mini-mally affected by prehistoric human impact, which could serve as a natural baseline condition for extant forest management. We hypothesise that during this period dense Abies-Fagus krummholz had an upper limit of 1570 m, with scattered Abies trees above this and open woodland of Sorbus, Betula and Acer up to the summit (1634 m a.s.l.). A varied cultural landscape was in place in medieval times, with cereal cultivation and grasslands in a predominantly forested landscape. A baseline condition of this kind of cultural landscape could be found in late medieval times. During the last several centuries major deforestations took place and planted Pinus sylvestris replaced much of the originally natural Abies-Fagus forest. Crop cultivation increased in the cultural landscape. All diagrams have hiatuses (missing peat layers), which in most cases could be attributed to domesticated ani-mals damaging the mire surface. For mire protection we therefore recommend a limited grazing pressure by cattle. The major phases in settlement history from the Neolithic to medieval times can be recognized in the pollen diagrams.