Pollen-based reconstruction of Holocene vegetation and climate in Southern Italy: the case of Lago di Trifoglietti
1CNRS USR3124 MSHE Ledoux, Besançon, France
2CNRS UMR6249 Laboratoire Chrono-Environnement, Université de Franche-Comté, Besançon, France
3CNRS UMR5276 LGL TPE, Université Lyon 1, Villeurbanne, France
4Dipartimento di Scienze Animali, Vegetali e dell'Ambiente, Università degli Studi del Molise, Campobasso, Italy
5CNRS UMR 7263 IMBE, Université d'Aix-Marseille, Aix en Provence, France
6Orto botanico, Università della Calabria, Cosenza, Italy
Abstract. A high-resolution pollen record from Lake Trifoglietti in Calabria (Southern Italy) provides new insights into the paleoenvironmental and palaeoclimatic changes which characterise the Holocene period in the Southern Italy. The chronology is based on 11 AMS radiocarbon dates from terrestrial macro-remains. The Holocene history of the vegetation cover shows the persistence of an important and relatively stable Fagus forest present over that entire period, offering a rare example of a woodstand able to withstand climate changes for more than 11 000 yr. Probably in relation with early Holocene dry climate conditions which affected Southern Italy, the Trifoglietti pollen record supports a southward delay in thermophilous forest expansion dated to ca. 13 500 cal. BP at Monticchio, ca. 11 000 cal. BP at Trifoglietti, and finally ca. 9800 cal. BP in Sicily. Regarding the human impact history, the Trifoglietti pollen record shows only poor imprints of agricultural activities and anthopogenic indicators, apart from those indicating pastoralism activities beneath forest cover. The selective exploitation of Abies appears to have been the strongest human impact on the Trifoglietti surroundings. On the basis of (1) a specific ratio between hygrophilous and terrestrial taxa, and (2) the modern analogue technique, the pollen data collected at Lake Trifoglietti led to the establishment of two palaeoclimatic records tracing changes in (1) lake depth and (2) annual precipitation. On a millennial scale, these records give evidence of increasing moisture from ca. 11 000 to ca. 9400 cal. BP and maximum humidity from ca. 9400 to ca. 6200 cal. BP, prior to a general trend towards the drier climate conditions that have prevailed up to the present. In addition, several successive centennial-scale oscillations appear to have punctuated the entire Holocene. The identification of a cold dry event around 11 300 cal. BP, responsible for a marked decline in timberline altitude and possibly equivalent to the PBO, remains to be confirmed by further investigations verifying both chronology and magnitude. Two cold and possibly drier Boreal oscillations developed at ca. 9800 and 9200 cal. BP. At Trifoglietti, the 8.2 kyr event corresponded at Trifoglietti to the onset of cooler and drier climatic conditions which persisted until ca. 7500 cal. BP. Finally, the second half of the Holocene was characterised by dry phases at ca. 6100–5200, 4400–3500, and 2500–1800 cal. BP, alternating with more humid phases at ca. 5200–4400 and ca. 3500–2500 cal. BP. Considered as a whole, these millennial-scale trends and centennial-scale climatic oscillations support contrasting patterns of palaeohydrological changes recognised between the North- and South-Central Mediterranean.