HOLOCENE PALEOENVIRONMENTS AT THE TIMBERLINE IN THE FRENCH ALPS - A MULTIDISCIPLINARY APPROACH

An attempt is made to reconstruct the palaeoenvironmental Holocene his tory at the timberline on the basis of the analysis of various palaeoe cological proxy indicators available on a marshy area and its surround ings in the Taillefer Massif (Isere, France). The multidisciplinary ap proach involves analyses of pollen assemblages, plant macrofossils, co leoptera remains, subfossil trunks extracted from lakes or peat-bogs, and charcoals derived from the surrounding soils. This enables definit ion of the respective roles of five forest taxa (Pinus uncinata Mill., Pinus cembra L., Larix decidua Mill., Abies alba Mill. and Picea abie s L. Karsten) in the evolution of high altitude forests during the Hol ocene. Pinus uncinata was present on the plateau throughout the Holoce ne. Larix and Pinus cembra were present only during two periods: 7500- 5000 BP and 3500-2000 BP. All trees disappeared from the plateau at ab out 2000 BP, while, at lower altitude, Abies was replaced by Picea. Th e action of both climate and early human impact can explain these chan ges.