Palynological analyses of the Late Pleistocene, Early Holocene and Middle Holocene layers

The palynological study of the Uan Tabu rock shelter performed a large spectrum of information on the environment that had characterised the Wadi Teshuinat in the Late Quaternary. In particular, pollen enlightened past changes of flora, vegetation, ecology, climate, ethnobotany and human influence in the area at the different times of the occupation of the site. The archaeological deposit of the rock shelter covered a range of about 60,000 years, from the Late Pleistocene to the Early and Middle Holocene, and was accumulated respectively during the Aterian, the Early/Late Acacus and the Late Pastoral different cultural phases. Twenty-one pollen samples were examined including twenty samples collected from the archaeological sequence and one dung sample collected from a niche of the wall of the rock shelter. A total of 4580 identified pollen grains were counted belonging to 105 pollen types. Based on pollen preservation, list and assemblages of taxa, we distinguished three main Pollen Zones corresponding well to the three chronological phases. The Late Pleistocene pollen spectra evidenced a wet climatic phase that occurred during the Late Glacial, possibly at around 14,000-11,000 years bp. At that time, in the area, the flora has already had the elements that will be characteristics of the Holocene and an open grassland or savannah-like vegetation was widespread. The Early Holocene pollen spectra showed that a gradual change from wet to relatively drier conditions characterised the phase from 9800 to 8600 years bp, and a main abrupt change towards dryness was evidenced at the end of the Early Holocene. All these factors certainly influenced human lifestyle of hunter-gatherers that should have been greatly conditioned by climate which changed environment and availability of plants in the area. The ensamble of pollen data, particularly those of the Holocene phases, testified that the flora of the area had been more various than today’s in the past, characterised by a mixture of tropical and Mediterranean-Saharan-linking plants. Certainly, vegetation should have been distributed at different belts, with Mediterranean forest-like vegetation standing in the upper belts, followed by a Saharo-montane vegetation. The latter, enriched by wet environment places, probably surrounded Uan Tabu. Desert dunes, when present, were more spread in the lowlands than in the Tadrart Acacus. In this context, the inhabitants of the rock shelter used a large spectrum of plants in different ways. The evidence was unquestionable for the Late Acacus phase because the maximum values of Anthropogenic Pollen grains were found there. Finally, the late Middle Holocene pollen spectrum of dung showed that a xerophilous vegetation, mainly a shrubby desert vegetation, was well-diffused in the area during a dry climatic phase. The process of aridification of the area was already evident probably enforced by human impact that at that time was mainly due to the grazing of domesticated animals of pastoralists.