On-site pollen data from Takarkori rockshelter: inferences on the Holocene landscape of the Central Sahara

Archaeobotanical studies on pollen and macro-remains, carried out within a multidisciplinary research framework, provided information on the past human-environment relationships and on the Holocene landscape evolution of Central Sahara. This has been repetitively obtained by the studies on rockshelters and caves which are widely distributed in this desert region. The site of Takarkori is a large rockshelter with a well preserved stratigraphic series located in the Acacus Mts. (south-western Libya, central Sahara), not far from the Algerian border. The excavations were carried out from 2003 to 2006 over a surface of ca. 120 square metres, and brought to light occupation levels radiocarbon dated between ca. 4500 and 8900 uncal. years bp. A sounding was done in the northern part of the site, in order to check the entire sequence. Here, around 140 cm of sandy sediment were excavated, testifying for a human occupation related to Late Acacus (“Mesolithic”), and to Early and Middle Pastoral Neolithic contexts. The palynological sequence has been mainly sampled on the southern wall of the sounding. There are 5 units, from the top containing different quantities of undecomposed straw, coprolites and hearths (Units I and II, Middle Pastoral), and then humified and loose layers (from Unit III-Early Pastoral, to Unit IV-V-Late Acacus). As the Early Pastoral and the Late Pastoral layers are not well preserved in this part of the site, other sediment samples have been collected in specific contexts, in order to balance this bias. The on-site pollen series consists of 30 samples. Pollen was common and better preserved in the bottom samples, from 80 to 140 cm deep, than in others. Pollen clusters, especially of Poaceae, phytoliths and microcharcoals were common. The pollen list includes about 90 taxa, representing a fairly high biodiversity. Obviously, most pollen was transported and accumulated into the shelter by humans. Nevertheless, the anthropogenic pollen accumulation is well distinguishable as generally concentrations are very high. In the different samples, main changes in the pollen list match changes in the local flora. Moreover, pollen curves of Poaceae and Chenopodiaceae clearly mark the decrease of savanna and the increase of desert communities in this region of Central Sahara, at the passage from the early Holocene towards the latest part of the middle Holocene. Studies on seeds/fruits, wood/charcoal, coprolites, plant ropes and baskets support the landscape reconstructions obtained by pollen spectra.