Palaeoenvironmental features of the early Middle Pleistocene site of Wadi Sarrat in NW Tunisia (Northern Africa)

This paper focuses on pollen and non-pollen palynomorphs (NPPs) analysis in a sequence from the archaeopalaeontological site of Wadi Sarrat (Tunisia). The series comprises a lapse time of Early-Middle Pleistocene vegetation succession and the evolution of the past lacustrine system of Wadi Sarrat. Some changes in the pollinic taxa are observed throughout the sequence in the region: fluctuations between Mediterranean (evergreen Quercus-type, Olea/Phillyrea, Pistacia, CISTACEAE, LAMIACEAE, CUPRESSACEAE, Pinus), mesic trees (deciduous Quercus-type, Myrica/Corylus, Alnus, Ulmus, Betula, Salix, Acer), hygro-hydrophytes (CYPERACEAE, Typha/Sparganium, Myriophyllum, PTERIDOPHYTA), and desert taxa (AMARANTHACEAE, APIACEAE, LACTUCEAE - ASTERACEAE, Ephedra, Asphodelus, CISTACEAE, Cerealia-type, BORAGINACEAE). The assemblages contained many desert elements (mostly herbaceous taxa) that occupy the high plateau and some trees that must come from the regional mountains or the banks of the lake. The NPPs and pollen analysis have allowed us to determine a cyclicity of nine events or pluvial phases, with tendencies to increase or decrease step by step. Taxa such as algae, Pseudoschizaea and Arcella have been of great help in the determination of the pluvial cycles.