Holocene environmental changes in the Lago Salso area (Tavoliere Plain - Southern Italy)

Molluscs, foraminifers and pollen were analysed from a 8.6 m deep core drilled in the Lago Salso area (Tavoliere Plain, Apulia, Italy), with the aim of reconstructing the environmental evolution in the vicinity of the Coppa Nevigata archaeological site during the last 6000 years. The archaeological settlement, inhabited from the Neolithic to the Iron Age, was situated at the edge of a broad lagoon, extending along an area of 40 km from the Gargano headland to the mouth of the Ofanto River. The core is located 0.8 km south-east of the archaeological site, within the former lagoon area. We found evidence that the lagoonal environment gradually became isolated from the sea, and finally changed into a terrestrial environment. Faunal assemblages found in the lower part of the core ("Hydrobiidae spp. and Cerastoderma Lagoon") are indicative of a progressively closing brackish environment. This favoured the presence of halophytes, recorded in the pollen diagram together with a moderate percentage of arboreal plants, representing both the deciduous vegetation of the nearby Gargano headland, and the Mediterranean evergreen vegetation of the coastal landscape. Lagoon sediments stopped to accumulate after approx 2770 cal BP. The beds corresponding to the next stage in the evolution of the site (the "Bithynia leachi Wetland") accumulated in a freshwater body until the XIX century. During this time interval the pollen diagram records the introduction of freshwater algae and marshy plants, a marked reduction of the arboreal vegetation and an increase of cultivated plants. In the third interval ("Terrestrial Phase"), corresponding to the last two centuries, the molluscs indicate an open and dry area, in which the vegetation was mostly herbaceous. Our data show that the landscape changes in the Lago Salso area during the last millennia result from a combination of different factors, including sea level fluctuations, climate variations towards more Mediterranean conditions, and local human impact on the environment since prehistoric times.