The Holocene at Lac de Creno, Corsica, France: a key site for the whole island

Abstract

Two Holocene lake sequences from Lac de Creno, Corsica were analysed on the basis of 119 pollen spectra and with the support of 13 "%C-calibrated dates. The lower part of one of these sequences, corresponding to the lateglacial period, has been published previously. The first third of the Post-glacial is characterized by very particular forest dynamics, namely the absence of a role for deciduous Quercus and Corylus, the presence of mesophilous vegetation types dominated by Taxus, and the major forest role of Erica arborea at lower and mean altitude. At about 7440 cal BP, the occurrence of a major anthropogenic action brought about significant changes in the vegetation, notably an increase of deciduous Quercus and the expansion of Quercus ilex. Later, three major humaninduced events are identified : the first, at about 2290 cal BP, is the cause of a short local expansion of Abies ; the second, at about 1150 cal BP, is the degradation of deciduous forests to the benefit of Fagus ; the third, at about 310 cal BP, corresponds to the disappearance of Fagus and its replacement by Pinus. Pollen data indicate that Q. ilex, Abies and Fagus are not indigenous in Corsica but spread there during the Postglacial ; this probably took place at about 6980 cal BP for Q. ilex.Key words : holocene, pollen spectra, vegetation history, Corsica, glacial vegetation. The island of Corsica is situated in the western Mediterranean basin, 80 km from the Italian coast and 160 km from the French coast (Fig. 1). The vegetation history of 28 sites since the late-glacial period has been described (Reille, 1975(Reille, , 1984(Reille, , 1992aReille & Burr, 1997). Among these sites, Lac de Creno is a key site, partly because it is situated at mean altitude (1310 m) and in the centre of the island (Fig. 2), but mainly because the infilling of the lake began in the late-glacial period, and no other site in Corsica provides such a complete sequence . However, the eight pollen sequences derived from the peaty border of the lake contained obvious hiatuses and hence the chronology was too uncertain (Reille, 1975). Accordingly, a new study of this site was undertaken, comprising pollen analysis and the detailed dating of a 6n5 m sublacustrine core taken at the centre of the lake. The 23 "%C-calibrated dates (either accelerator mass spectrometry (AMS) *Author for correspondence (fax j33 4 91 28 86 68 ; e-mail valerie.andrieu!lbhp.u-3mrs.fr).or classical) obtained for this sequence (159 pollen spectra) indicate a chronology suggesting that the sedimentation of the lake started towards 17 480 cal BP, that is to say at the beginning of the late-glacial period .The results relating to the late-glacial period and the beginning of the Holocene were published in an earlier article where the reader will find a general outline of the geology and geography of Corsica, the present vegetation, and the ecology and distribution of the main taxa (Pinus nigra ssp. laricio, Betula pendula, Alnus viridis ssp. suaveolens), as well as a description of th...

Controls on Holocene denudation rates in mountainous environments under Mediterranean climate

“…The climate in Corsica was colder in the past (Kuhlemann et al , ) and the vegetation was mainly constituted of steppes during late glacial and the first thousands years of the postglacial period (Reille et al ., ). The present‐day pattern of forests in Corsica has been nearly the same for the last 7–8 ka (Reille et al ., ). This pattern is mainly controlled by constant parameters (exposition, altitude, relative humidity, type of substratum, etc.).…”

“…Strong seasonal variations in precipitation result in high flood discharge from the Golo River, with an average discharge of 20.4 m 3 s ‐1 and a flood peak reaching 734 m 3 s ‐1 (HYDRO French Database, www.hydro.eaufrance.fr). Vegetation is dominated by evergreen bushes and trees in the lowlands with increasing amounts of deciduous and pine forest at higher elevations (Reille et al , ). There is no recent glacier permanent ice in the studied area (Wilhelm, ), but the uppermost part of the Golo watershed was glaciated during the Last Glacial Maximum (LGM) and subsequent glacial phases (Klaer, ; Kuhlemann et al , ; Krumrei, ).…”

Genetic diversity and gene flow between the wild olive (oleaster, Olea europaea L.) and the olive: several Plio‐Pleistocene refuge zones in the Mediterranean basin suggested by simple sequence repeats analysis

“…, 2002) have revealed unusual patterns of diversity for Corsican oleasters and olives. It is questionable whether the genuine oleaster occurred in Corsica, and could therefore be feral, as historical and botanical data are lacking, although its presence has been observed in pollen records (Reille et al. , 1999).…”

Towards a glacial‐sensitive model of island biogeography

“…; Haberle, ), Corsica (2706 m a.s.l. ; Reille et al ., ), Maui (3055 m a.s.l. ; Burney et al ., ) and Taiwan (3952 m a.s.l.…”