First fluvial archive of the 8.2 and 7.6-7.3 ka events in North Africa (Charef River, High Plateaus, NE Morocco).

The Early-Mid Holocene transition is a period of profound changes in climatic mechanisms and hydrological features in Europe and North Africa. The melting of the Laurentide ice sheet led to an oceanic and atmospheric reorganisation in the North Atlantic, while the Mediterranean underwent a major hydrological shift. The impacts on Mediterranean rivers remain unclear, as there are few records documenting responses to the 8.2 ka event (the main Holocene climatic degradation). We present a fluvial record from Eastern Morocco documenting detailed hydrological variations from 8200 to 7500 cal. BP and their climatic forcing. A major hydrogeomorphic evolution of the Charef River occurred at that time, marked by two major incision stages close in time, under hyper-arid conditions at 8200 and ca. 7500 cal. BP. The impacts of these phenomena on the alluvial plains and associated archaeological records during Neolithisation, a major process in human history, currently remain unidentified. This new record sheds light on the fluvial response to the 8.2 ka event in North Africa and why other records are missing. We also bring new insights into the hydrological disruption at the Early-Mid Holocene transition, which was driven by the end of deglaciation combined with insolation and solar forcing. Furthermore, centennial solar variability may have paced river activity in the Moulouya basin and arid regions of North Africa.

First high resolution chronostratigraphy for the early North African Acheulean at Casablanca (Morocco).

The onset of the Acheulean, marked by the emergence of large cutting tools (LCTs), is considered a major technological advance in the Early Stone Age and a key turning point in human evolution. The Acheulean originated in East Africa at ~ 1.8-1.6 Ma and is reported in South Africa between ~ 1.6 and > 1.0 Ma. The timing of its appearance and development in North Africa have been poorly known due to the near-absence of well-dated sites in reliable contexts. The ~ 1 Ma stone artefacts of Tighennif (Algeria) and Thomas Quarry I-Unit L (ThI-L) at Casablanca (Morocco) are thus far regarded as documenting the oldest Acheulean in North Africa but whatever the precision of their stratigraphical position, both deserve a better chronology. Here we provide a chronology for ThI-L, based on new magnetostratigraphic and geochemical data. Added to the existing lithostratigraphy of the Casablanca sequence, these results provide the first robust chronostratigraphic framework for the early North African Acheulean and firmly establish its emergence in this part of the continent back at least to ~ 1.3 Ma.

Continuous presence of proto-cereals in Anatolia since 2.3 Ma, and their possible co-evolution with large herbivores and hominins.

Cereals are a central resource for the human diet and are traditionally assumed to have evolved from wild grasses at the onset of the Neolithic under the pressure of agriculture. Here we demonstrate that cereals may have a significantly longer and more diverse lineage, based on the study of a 0-2.3 Ma, 601 m long sedimentary core from Lake Acigöl (South-West Anatolia). Pollen characteristic of cereals is abundant throughout the sedimentary sequence. The presence of large lakes within this arid bioclimatic zone led to the concentration of large herbivore herds, as indicated by the continuous occurrence of coprophilous fungi spores in the record. Our hypothesis is that the effects of overgrazing on soils and herbaceous stratum, during this long period, led to genetic modifications of the Poaceae taxa and to the appearance of proto-cereals. The simultaneous presence of hominins is attested as early as about 1.4 Ma in the lake vicinity, and 1.8 Ma in Georgia and Levant. These ancient hominins probably benefited from the availability of these proto-cereals, rich in nutrients, as well as various other edible plants, opening the way, in this region of the Middle East, to a process of domestication, which reached its full development during the Neolithic.

Early impact of agropastoral activities and climate on the littoral landscape of Corsica since mid-Holocene.

A multidisciplinary study (geomorphology, sedimentology and palynology) shows that the landscapes of the southwest coast of Corsica have been deeply modified by humans and the climate since 3000 BC. Significant and rapid landscape transformations are recorded between the Chalcolithic and the Middle Bronze Ages (3000-1300 BC). Several major (2.2 ka BC, 1.2 ka BC) and local (3000 BC) detrital events affected the Taravo Lower Valley in relation to global climatic changes and anthropic activities. The vegetation dynamics since 3000 BC show alternating phases of agriculture and abandonment until the complete disappearance of the original forest populations in the vicinity of the Canniccia Marshes. An early phase of Olea cultivation is recorded between 2900 and 2300 BC. Plant macro-remains indicate that cereals, vine and many species of Fabaceae were cultivated in the nearby of the archaeological sites during the middle to the late Chalcolithic Age. The event of 2.2 ka BC corresponds to an abandonment phase in the lower Taravo Valley. Pastoralism dominated agricultural activities between 2200 and 1700 BC. During Roman times, agriculture is characterized by olive and vine cultivation. A new peak of pastoralism and the cultivation of Castanea are noted during invasion times (500 to 1000 AD), showing that invasions didn't disturb agricultural activities in the Taravo Valley. During the Pisa Period (end of the 9th C. to then end of 13th C. AD), pastoralism declined and vine and cereals were cultivated in the very nearby of the Canniccia Marshes. During the Genoa Period upwards (end of the 13th C. to 1769 AD), a decline in agriculture and a recrudescence of the forest (maquis and pine) are recorded, leading to the settlement of a present-day vegetal landscape dominated by an Erica arborea maquis.

Range expansion of the Asian native giant resin bee Megachile sculpturalis (Hymenoptera, Apoidea, Megachilidae) in France.

In 2008, a new species for the French bee fauna was recorded in Allauch near Marseille: the giant resin bee, Megachile sculpturalis (Smith, 1853). This was the first European record of this species that is native to East Asia. To our knowledge, it is the first introduced bee species in Europe. Here, we provide an overview of the current distribution of M. sculpturalis in France and we describe the history of its range expansion. Besides our own observations, information was compiled from literature and Internet websites, and by contacting naturalist networks. We collected a total of 117 records (locality × year combinations) for the 2008-2016 period. The geographical range of M. sculpturalis has extended remarkably, now occupying a third of continental France, with the most northern and western records located 335 and 520 km from Allauch, respectively. Information on its phenology, feeding, and nesting behavior is also provided. We report several events of nest occupation or eviction of Osmia sp. and Xylocopa sp. individuals by M. sculpturalis. Our results show that M. sculpturalis is now well established in France. Given its capacity to adapt and rapidly expand its range, we recommend amplifying the monitoring of this species to better anticipate the changes in its geographical range and its potential impacts on native bees.

[Pollen analysis from two littoral marshes (Bourdim and Garaat El-Ouez) in the El-Kala wet complex (North-East Algeria). Lateglacial and Holocene history of Algerian vegetation]. / Nouvelles contributions à l'histoire tardiglaciaire et holocène de la végétation en Algérie: analyses polliniques de deux profils sédimentaires du complexe humide d'El-Kala.

The study of two pollen sequences from El-Kala marshes allowed the reconstruction of the regional vegetation history supported by eight radiocarbon dates. Pollen assemblages from Bourdim site were dominated by local input of Alnus and Salix, while regional vegetation was characterized by scattered Quercus suber forests with a well-developed Erica arborea matorral. While the vegetation dynamics recorded at Bourdim is recent (Late Holocene), the majority of the pollen diagram from Garaat El-Ouez is contemporaneous to the Late Pleniglacial and is characterized by open woodlands with Pinus, Poaceae and several heliophilous herbs. The significant values of Cedrus pollen identified in this period indicate that the region of El-Kala most probably played the role of a refugium for this tree.

Similarity of vegetation dynamics during interglacial periods.

The Velay sequence (France) provides a unique, continuous, palynological record spanning the last four climatic cycles. A pollen-based reconstruction of temperature and precipitation displays marked climatic cycles. An analysis of the climate and vegetation changes during the interglacial periods reveals comparable features and identical major vegetation successions. Although Marine Isotope Stage (MIS) 11.3 and the Holocene had similar earth precessional variations, their correspondence in terms of vegetation dynamics is low. MIS 9.5, 7.5, and especially 5.5 display closer correlation to the Holocene than MIS 11.3. Ecological factors, such as the distribution and composition of glacial refugia or postglacial migration patterns, may explain these discrepancies. Comparison of ecosystem dynamics during the past five interglacials suggests that vegetation development in the current interglacial has no analogue from the past 500,000 years.

[Palynological evidence of anthropogenic pressure: effect on pollination dynamics in the Evian area since the middle Neolithic: the pollen record of La Beunaz (971 m a.s.l., northern Alps, France)]. / Impact anthropique sur la végétation de la région d'Evian depuis le Néolithique moyen: l'enregistrement pollinique de la Beunaz (971 m n.g.f., Haute-Savoie, France).

This paper presents a pollen diagram from La Beunaz peat-bog (southeast of Evian, Haute-Savoie, France), which provides the first detailed record of human impact on vegetation of the southern bank of Lake Geneva since the Middle Neolithic. The radiocarbon-dated pollen profile is correlated with micro-charcoal record and archaeological data. The results suggest that several phases of deforestations since 4615+75/-70 years BP occurred, in relation to human activities (agriculture, pastoralism). Tombs and vestiges of lacustrine villages indicate that the region was intensively and recurrently occupied by man during at that time.