Holocene environmental reconstruction in Southern Calabria (Italy): an integrated anthracological and pedological approach

Multidisciplinarity is an essential tool in reconstructing past environment and landscape. In this poster we present the application of archaeoanthracological analysis, together with pedoanthracology and pedology, for understanding environmental changes in two different areas of Calabria (South Italy). The two considered sites are Cecita Lake and Palmi, situated in north central-inland and south-western coastal Calabria, respectively (Fig. 1). Cecita Lake is an artificial lake located on the Sila Massif at about 1130-1140 m a.s.l. in a tectonic depression filled up, probably since late Early-Middle Pleistocene through Late Pleistocene, by fluvial-lacustrine sediments related to a palaeo-lake. The main vegetation is composed by grassland and cultivated fields and beech (Fagus sylvatica) and oak forest (Quercus cerris). The high mountain belt is made of conifers dominated by pine (Pinus laricio) and fir (Abies alba). The latter are the result of recent reforestation policies and progressive renaturalization. Human occupation along lake shores from late Neolithic to early Eneolithic (5800-5350 years BP) and from Greek time (6th to 3rd century BC) to Roman Republican and late Imperial Age (3rd – 1st century BC to 5th – 6th century AD) is documented by settlements and archaeological findings. The excavation close to Palmi (Piani della Corona site) is situated on a wide terrace at about 500 m a.s.l., along the southern Tyrrhenian coast of Calabria, characterized by a sequence of Pleistocene marine terraces. A pedostratigraphic succession already described by Bernasconi et al. (2010) is present, including late Neolithic settlements and artifacts (about 6500-5800 years BP). They are partly truncated and buried by anthropogenic disturbance, that displays repeated ploughing traces of undifferentiated historical epochs, separated by a late early Bronze Age paleosurface (about 4000-3700 years BP). This surface is in turn affected by marks of archaeological structures, ploughing and various excavations. The methodology has envisaged a first geomorphological and pedological characterization and description of the soil profile and the subsequent collection of soil samples for pedological and anthracological analysis. In the case of Cecita Lake only late prehistoric and Roman soils were sampled, because at present the Greek site is submerged about 6 m below lake level. They all consist of surface A horizons, in places affected by repeated prehistoric to modern ploughing traces (Ap). In the Neolithic soil the A horizon exhibits scarce clay coatings in pores and overlies a Bw horizon. At Palmi the upper profile was sampled: samples were collected from the deep argillic (Btb) horizon dated to late Neolithic, from the late early Bronze Age paleosurface (Ab) and, above this Bronze paleosurface, from the upper stratigraphic succession consisting of brown anthropogenically disturbed organic-mineral (Ap) horizons that appear cyclically ploughed during historical times, but archaeologically not well dated because of their reworking for agricultural practices (Bernasconi et al. 2010). The deepest part of the soil profile is going to be dated by AMS dating to have the most ancient chronological limit. For archaeo- and pedoanthracological analysis the samples were sieved by water through a sieving column with 2, 1, 0.5 and 0.25 mm mesh size. Charcoal fragments with >2 mm size were sorted; the taxonomical determinations have been made by an incident light microscope at magnification 100x, 200x and 500x, using specialist literature, wood anatomy atlases (e.g. Greguss, 1959; Schweingruber, 1990) and reference collections of wood. Above soils from both sites partly developed on volcanic ash and display variable Andisol-like features related to formation of some amounts of short-range order minerals. Ash composition, the pedostratigrahic position and some radiometric dates suggest a provenance from late Pleistocene/Holocene explosive eruptions of the Aeolian Islands (Scarciglia et al., 2008; Bernasconi et al., 2010), about 80 to 170 km far to the southwest from Palmi and Cecita Lake, respectively. Micromorphological observations performed in thin sections prepared from undisturbed soil samples, highlighted the occurrence of clay coatings in the Neolithic layers of both sites, and their relict significance (e.g. Kemp, 1998). These features suggest climatic conditions characterized by high moisture availability and some seasonal contrast, enhanced by a warm-humid climate. Therefore, main soil development may have occurred during the late early-middle Holocene climatic optimum (Scarciglia et al., 2008; Bernasconi et al., 2010; Pelle et al., 2010). The post-Neolithic soil horizons (Roman age at Cecita and undetermined at Palmi) show more abundant short-range order minerals than phyllosilicates and no to very rare clay coatings, that suggest climatic changes towards overall prolonged humid (and probably cooler) conditions. Between the two distinct climatic phases identified during and after the Neolithic, a severe land degradation is also recorded, testified by human impact (deforestation, cultivation and other activities) and soil erosion. Archaeo and pedoanthracological data from Cecita Lake give good evidence of it. In fact, charcoal fragments from Neolithic soils are dominated by deciduous oak forest (mainly Quercus deciduous type), whereas a transition to a mountain pine forest dominated by Pinus sylvestris group is recorded in the Roman soils. Preliminary soil charcoal data from Palmi, instead, suggest a stability of forest cover characterized by a deciduous forest dominated by oaks; in fact this taxon is present both in the Neolithic and in the post- Bronze Age horizons. It is noteworthy the presence of Abies alba, belonging today only to mountain vegetation, identified in a Neolithic horizon. It cannot be ruled out that also some effects of climate drying (one or more episodes known in the literature; e.g. Mayewski, 2004; Di Donato et al., 2008) could have enhanced land degradation after the Neolithic climatic optimum, as also coherent with above decrease or interruption of clay illuviation in younger soils. However, in the mountainous one of Cecita Lake, the decline of the deciduous oak forest could mainly be caused by the human overexploitation of the forest resource. To better determine the significance of climate or human influence in this area two new soil profiles from Cecita Lake are going to be analyzed by the pedoanthracological point of view with the aim to have a more detailed chronological succession and a more accurate date for the shift from the deciduous oak forest to the mountain pine forest. New AMS dating is going to be add to the pedoanthracological analysis. AMS dating is required also for both the data concerning the silver fir and post Bronze Age oak found at Palmi.