Dendi Lake Rockshelter is situated about 100 km west of Addis Ababa on the west-central part of the Ethiopian Plateau in the Ginchi woreda of Ethiopia's Oromiya regional state. In October 2012, a team from the University of Cologne excavated a testtrench that revealed four archaeological complexes that could clearly be distinguished on a typological basis as well as by radiocarbon dates. This article focuses on the lithic artefacts recovered from the excavation and specifically the microliths that are one of the main characteristics of the Later Stone Age. Their high variability in this assemblage is a common feature of contemporaneous sites in the Horn of Africa. The rockshelter is situated in a high-altitude Afromontane forest and was most probably used for short-term stays by groups of hunters. RÉSUMÉLe refuge de Dendi Lake Rock Shelter est situé à environ 100 km à l'ouest d'Addis Abeba, sur le plateau éthiopien du centre-ouest, dans le woreda de Ginchi de l'État régional d'Oromiya, en Éthiopie. En octobre 2012, une équipe de l'Université de Cologne a réalisé un sondage qui a révélé quatre complexes archéologiques clairement distingués par les modes typologiques ainsi que par les datations radiocarbones. L'article portera principalement sur l'industrie lithique, notamment les microlithes qui sont l'une des principales caractéristiques du Later Stone Age. Leur grande variabilité dans cet assemblage est une caractéristique commune aux sites contemporains de la Corne de l'Afrique. L'abri est situé dans une forêt afromontane de haute altitude et était très probablement utilisé par des groupes de chasseurs pour des séjours de courte durée.

During the past 25 ka, southern Ethiopia has undergone tremendous climatic changes, from dry and relatively cold during the Last Glacial Maximum (LGM, 25–18 ka) to the African Humid Period (AHP, 15–5 ka), and back to present-day dry conditions. As a contribution to better understand the effects of climate change on vegetation and lakes, we here present a new Predictive Vegetation Model that is linked with a Lake Balance Model and available vegetation-proxy records from southern Ethiopia including a new phytolith record from the Chew Bahir basin. We constructed a detailed paleo-landcover map of southern Ethiopia during the LGM, AHP (with and without influence of the Congo Air Boundary) and the modern-day potential natural landcover. Compared to today, we observe a 15–20% reduction in moisture availability during the LGM with widespread open landscapes and only few remaining forest refugia. We identify 25–40% increased moisture availability during the AHP with prevailing forests in the mid-altitudes and indications that modern anthropogenic landcover change has affected the water balance. In comparison with existing archaeological records, we find that human occupations tend to correspond with open landscapes during the late Pleistocene and Holocene in southern Ethiopia.

<p>Modern-day southern Ethiopia exhibits a complex mosaic of vegetation types. These types range from desert scrubland along the shores of Lake Turkana, to woodlands and wooded grasslands in the Omo-River-Lowlands and Chew Bahir catchment, and Afromontane forests of the Ethiopian Highlands. Over the past 20 ka, this region has experienced a variable climate, from the dry Last Glacial Maximum (25-18 ka BP) to the wet African Humid Period (15-5 ka BP), and back to present-day dry conditions. These oscillations likely had an impact on the biosphere and its human inhabitants. The biosphere, especially climate-induced changes in vegetation, in turn have a feedback effect on the local climate – and must therefore be considered in climate models and hydro-balance models. However, there are hardly any data on changes in vegetation during the dry-humid-dry transition of the AHP that could be used to parameterize such models.</p><p>As a contribution to an enhanced understanding of the role that paleo-vegetation could have played during those transitions, we present here a new comprehensive vegetation model. This study links a Predictive Vegetation Model (PVM) with the available vegetation-proxy records from southern Ethiopia, including a new phytolith record from Chew Bahir. The PVM uses an 18-year averaged time series of the Global Precipitation Measurement as well as SRTM elevation data to predict an 18-year averaged time series of MODIS landcover and vegetation parameters using boosted regression trees. We linked the PVM and resulting surface parameters (moisture availability, surface drag coefficient, albedo) with an existing hydro-balance model of the southern Ethiopian Rift to calculate precipitation during the AHP and hence also model the paleo-vegetation during this period. Available paleo-vegetation data including a new grass phytolith record from the sediments of an 11 m-meter long sediment core from the margin of paleo-Lake Chew Bahir were then used to compare model and proxy results. Being able to validate our new model data with actual vegetation proxy data for the first time enables us to gain valuable insights into the paleo-dimension of the vegetation mosaic of southern Ethiopia, a possible habitat of early<em> Homo sapiens</em>.</p>

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