The Paleolithic site of Poggetti Vecchi (GR) : a paleopalynology research

In 2012, during excavation of a small basin, a prehistoric site was discovered at Poggetti Vecchi, Grosseto (south Tuscany, Fig. 1). The excavation revealed a long stratigraphic sequence with numerous vertebrate bones (Palaeoloxodon antiquus and other mammals), wooden and stone tools in the lower units (1): indeed, archeological investigations suggest an iterated occupancy starting at Lower/Middle Paleolithic. Wooden tools were mainly made of Buxus sempervirens. Palynological analysis were carried out to gather information about the environmental evolution of the surrounding area in the period of human frequentation and to evidence exploitation of the plant resources. Samples were taken along two stratigraphic sequences: PV1 out-site, and PV2 on-site. A cushion moss picked up near the study area made possible to compare the present vegetation with that of the past. All the samples were treated with the routine methodologies and observed at light microscope. The analysis revealed a high pollen content and a good grain preservation in all the sample tested: this made possible an accurate reconstruction of the flora and compiling a list of taxa of nearly 100 different morphotypes. The results indicate the study area as an extensive grassland dominated by herbaceous formations typical of wet and moist substrates. The most represented family are Poaceae. The percentage variations of hygro-hydrophilus taxa along the sequence suggest repeated rises and falls of the water table in the alluvial plain. Hygrophilous trees of riparian vegetation like Alnus sp., Salix sp. and Populus sp. were also recorded. Low pollen percentages suggested the occurrence of mixed oak woods probably widespread on the hillside surrounding the site: the pollen of these plants could have been transported to the plain by air and by watercourses. Interestingly, low values of Buxus pollen grains were found along all the sequence, despite its short dispersal distances (2) and preservation in the sediments. The presence of Buxus, which usually grows on well-drained calcareous substrates as it is the case of the Poggetti Vecchi site, hints human exploitation of the local timber. Xerophilous taxa such as Pinus sp. and Cupressaceae were sporadically recorded.