image/svg+xml151 VI/2/2015 INTERDISCIPLINARIA ARCHAEOLOGICA NATURAL SCIENCES IN ARCHAEOLOGY homepage: http://www.iansa.eu Humans and Water in Desert “Refugium” Areas: Palynological Evidence of Climate Oscillations and Cultural Developments in Early and Mid-Holocene Saharan Edges Anna Maria Mercuri a , Assunta Florenzano a* , Carlo Giraudi b , Elena A. A. Garcea c a Laboratorio di Palinologia e Paleobotanica, Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, viale Caduti in Guerra 127, 41121 Modena, MO, Italy b ENEA C. R. Saluggia, Strada per Crescentino 41, 13040 Saluggia, VC, Italy c Dipartimento di Lettere e Filosofa, Università di Cassino e del Lazio Meridionale, via Zamosch 43, 03043 Cassino, FR, Italy 1. Introduction The concept of a refugium is frequently combined with that of mountains in desert ecosystems (Quézel 1997; Anthelme et al. 2008; Migliore et al. 2013). Evolutionary and ecological refuges have different chronological and spatial scales (Quézel, Martinez 1960; Maley 1981, 2010; Bennet, Provan 2008; Watrin et al. 2009; Davis et al. 2013), but both may be recognised in the history of currently hyper-arid regions. Although there are different approaches to this matter, in general, refugia are regarded as places where the local microclimate was different from the regional climate, and therefore organisms may have retreated, persisted in or expanded from , under changing environmental conditions (according to the habitat-based defnition of refugia by Keppel et al. 2012). Under dry or cold climate oscillations, for example, organisms have a higher chance of survival in these places.With regard to deserts, including current ethnographic evidence (Mandaville 2011; di Lernia et al. 2012), it is especially evident that, little by little, water has triggered the movements of plants, animals and humans. Across the history of desert regions, organisms have followed water, and when climate conditions became drier and water basins and rivers reduced their distribution or fow, then humans have reached the same refuges where water and plants have already concentrated (Kuper, Kröpelin 2006; Mercuri 2008a; Florenzano et al. 2016).This leaves open the question as to whether the plant cover near places of water (or wetlands) is natural or anthropogenic.Saharan anthropic deposits from archaeological sites, located along wadis or close to lakes, and sedimentary sequences from permanent and dried basins, have demonstrated that water has been an attractive environmental feature especially during periods of drought ( e.g. , Smith et al. 2005; Garcea 2013a). Volume VI ● Issue 2/2015 ● Pages 151–160 *Corresponding author. E-mail: assunta.forenzano@unimore.it ARTICLE INFO Article history: Received: 30 th April 2015Accepted: 21 st December 2015 Key words: palaeoecologypollenwet habitatsarchaeologyclimate changeLibyaNiger ABSTRACT Saharan anthropic deposits from archaeological sites, located along wadis or close to lakes, and sedimentary sequences from permanent and dried basins demonstrate that water has always been an attractive environmental feature, especially during periods of drought. This paper reports on two very different examples of Holocene sites where “humans and water” coexisted during dry periods, as observed by stratigraphic, archaeological and palynological evidence. Independent research was carried out on the Jefara Plain (Libya, 32°N) and the Gobero area (Niger, 17°N), at the extreme northern and southern limits of the Sahara, respectively.The histories of the Jefara and Gobero areas, as revealed by the archaeological and palaeoenvironmen-tal reconstructions, suggest that these areas were likely to have been visited and exploited for a long time, acting as anthropic refugia, and therefore they have been profoundly transformed. Human presen-ce and actions have conditioned the local growing of plants and selected a more or less synanthropic fora. Today, modern conservation strategies should take into consideration that water reservoirs, which are crucial for the long-term conservation of biodiversity, have provided refugia in the past just as they presently do under global warming conditions.
image/svg+xmlIANSA 2015 ● VI/2 ● 151–160 Anna Maria Mercuri, Assunta Florenzano, Carlo Giraudi, Elena A. A. Garcea: Humans and Water in Desert “Refugium” Areas: Palynological Evidence of Climate Oscillations and Cultural Developments in Early and Mid-Holocene Saharan Edges 152 This paper reports on two, very different, examples of evidence concerning “humans and water” as observed in the stratigraphic, archaeological and palynological studies carried out on Holocene deposits at the extreme limits of northern and southern Sahara. 2. The case studies The two case studies reported in this paper come from the Jefara Plain (Libya, 32°N) to the north and the Gobero region (Niger, 17°N) to the south of the present Sahara desert (Figure 1). They currently lie at the margins of the widest desert of the world, both regions that are known to receive more rainfall and have greater vegetation cover than the central regions. Central Sahara lies between 18º and 30º N, its annual rainfall is below 25 mm, and its underground aquifers sometimes penetrate through to the surface resulting in oases (White 1983).The areas of the Jefara and Gobero have been studied using an interdisciplinary approach that involved environmental investigations in the general archaeological research. Palaeoenvironmental reconstructions resulted from an integration of archaeological, geological, sedimentological and palynological studies in the two areas. In fact, they are both multipoint sites characterised by a complex set of sedimentary and cultural contexts (Giraudi 1995; 2005; Barich et al. 2006; Garcea, Giraudi 2006; Sereno et al. 2008; Barich 2013; Garcea 2013a).Pollen analyses resulted in a very laborious and time-consuming procedure. Many sandy and organic-poor types of sediment were treated for pollen extraction through sieving and foating procedures (van der Kaars et al. 2001; Florenzano et al. 2012). Although several grams of sediment were processed, quite a lot of samples were sterile and others showed very low pollen concentration (expressed as pollen grains per gram = p/g). Nevertheless, pollen in a good state of preservation was found in several samples. The high interest of these contexts, commonly associated with archaeological deposits and radiocarbon dating, encouraged the accomplishment of these pollen analyses and gave the possibility to compare the pollen data with the other results obtained from different analyses. 2.1 Case study 1: the Jefara Plain (Libya; 32°00′ N, 11°41′ E; c. 230 m asl; c. 7800–4600 cal BP) At the northern fringes of the Sahara desert, Quaternary sedimentary sequences were identifed in the Jefara Plain in front of the northern scarp of the Jebel Gharbi, a mountain range in northwestern Libya. These sequences were mostly formed of dark-grey palustrine sediments interbedded with aeolian deposits; these were studied in order to establish the timing of marsh formation and the periods of increased groundwater fow (Giraudi et al. 2013). Moreover, a number of Neolithic archaeological features, especially hearths, suggested that human frequentation had occurred on a seasonal basis for those transiting between the Mediterranean coast and the mountain range and the pasture of livestock (Lucarini 2013).As the geomorphologic and stratigraphic features of the Jebel Gharbi and the Jefara Plain showed that Holocene sediments were rather discontinuous in this area, since they had been subjected to strong wind defation and erosion by ephemeral streams, two sites about 300 m apart, SJ-06-87 and SJ-06-88, where the aeolian sediments were interbedded with dark palustrine sediments, were selected