Jouanneau, Jean-Marie

Naughton, Filipa

Oliveira, Dulce

Rodrigues, Teresa

Trigo, R.

Weber, Olivier

Repositório do LNEG

Geophysical Research AbstractsVol. 14, EGU2012-10699, 2012EGU General Assembly 2012© Author(s) 2012Holocene climate variability in south-western FranceD. Oliveira (1,2), F. Naughton (1,2), R. Trigo (3), T. Rodrigues (1,2), J-M. Jouanneau (4), and O. Weber (4)(1) LNEG, Marine Geology Research Unit, Alfragide, Portugal , (2) CIIMAR, Porto, Portugal, (3) CGUL IDL, University ofLisbon, Lisbon, Portugal, (4) UMR-CNRS EPOC 5805, Bordeaux 1 University, FranceVegetation and climate changes in western France/northern Spain are documented for the last c. 9000 cal. yr BPin a well dated shelf core, KS05-10, retrieved in the southwestern margin of the Bay of Biscay (Basque country)(43◦22’765N, 2◦16’744W).The continuous high resolution pollen record shows orbital and suborbital climate fluctuations similar to thosenoticed for the North Atlantic region and Greenland. A long-term Pinus, Quercus and Corylus forest reductionfollows the cooling trend in Greenland and the general decrease of mid-latitude summer insolation until approxi-mately 350 yr cal. BP. Within the millennial scale variability, the southwestern Bay of Biscay pollen record shows6 main phases:The first phase, c. 9000 and 6600 cal. yr BP, is marked by a Pinus and deciduous Quercus forest with Corylus,indicating a humid and temperate climate. During the phase, c. 6600 - 4500 cal. yr BP, the pollen record shows astable period of rich, mixed Quercus forest. During this interval occurred the establishment of Alnus, Ulmus, Tilia,Fraxinus excelsior-type and Fagus trees and the reduction of Pinus forest. This vegetation assemblage probablyindicates an increase in moisture in relatively mild conditions. Fagus became continuously present in the regionafter c. 4500 c. cal. yr BP in agreement with what have been noticed by continental pollen sequences.An important contraction of Pinus, deciduous Quercus and Corylus forest occur after c. 3600 cal. yr BP. Thisevolution is contemporaneous to the maximum expansion of Fagus and the increase of heaths, which may belinked to a weakening of seasonality and more humid summer conditions. A strong forest reduction, involving alltrees except pine, and a marked spread of herbaceous plants took place after c. 1400 cal. years BP. The presenceof Juglans, Cerealia type and Castanea after c. 550 cal. yr BP and the re-expansion of Pinus after c. 350 cal. yr BPtestify the increasing role played by the human activity in the region.

Holocene climate variability in south-western France

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Holocene climate variability in south-western France

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