Résumé
We use pollen, stomata and plant-macrofossil records to infer Holocene timberline fluctuations and changes in forest composition at Lac Superieur de Fully (2 135 in a.s.l.), a small lake located near the modern regional timberline on a highland plateau in the Central Alps. Our records suggest that during the early Holocene vegetation was rather open on the plateau (eg, heaths of Dryas octopetala, Juniperus nana). The only tree that was able to build major stands was Belula. Other timberline trees (eg, Pinus cembra and Larix) expanded in the catchment of the lake after 8200 cal. BP, when Abies alha expanded at lower elevation. The late appearance of these timberline trees contrasts with previous plant-macrofossil records in the region, which show that the timberline had reached elevations up to at least 2350 in already at I 1000 cal. BP. We suggest that local climatic conditions may have delayed the expansion of closed stands of coniferous trees in the catchment of Lac de Fully until C. 8200 cal. BP, when climate shifted to more humid and less continental conditions. After c. 4600 cal. BP vegetation around the lake primarily responded to human impact, which caused a local lowering of the timberline by at least 150 in.