Mid Holocene vegetation reconstruction from Vanevan peat (south-eastern shore of Lake Sevan, Armenia)

International audienceA sediment core has been retrieved from Vanevan peat (south-eastern shore of Lake Sevan, Armenia), which is today disconnected from Lake Sevan thanks to an artificial shallowing of the lake. Based on 5 radiocarbon dates, Vanevan record covers the Mid Holocene (from ca. 7800 to ca. 5100 cal. BP). The Late Holocene is today absent in the peat stratigraphy due to modern peat exploitation by surface mining. This study focuses on a multi-proxy approach including pollen, charcoals, and pollen-inferred climate reconstruction. An open-land, steppic vegetation is recorded up to ca. 7700 cal. BP, followed by a more forested landscape during the Mid Holocene (up to ca. 5700 cal. BP), and ending again with an open-land vegetation (to the end of record, 5100 cal. BP). This vegetation dynamics responds to general climate changes documented in the Near East. Whether human activities are documented since ca. 7500 cal. BP (Late Neolithic) in Vanevan, they remain marginal and probably did not affect the area. Early Holocene dry climate, which caused the steppic environment to be widespread through the Near East, is strongly related to low late spring precipitation (PMay–Jun = 180 mm). Mid Holocene forested landscape and increasing lake-level seem related to late spring precipitation (+28%), which is the main change in estimated climate parameters. This has to be linked with reinforcement of the Westerlies and less active Siberian High, which are inversely involved in the following, dry phase starting at ca. 5700 cal. B

Upper Holocene vegetation history from the Kalavan Red Lake in Armenia

International audienceVegetation change based on the study of pollen from sediments in the Kalavan Red Lake (1912 m a.s.l.), located on the northern side of the Miapor mountain ridge in Armenia, has been interpreted.This exceptional small lake with red shores coloured by iron oxides is ideally placed in the beech-oak vegetation zone, about three kilometers from archaeological remains. It thus has the potential to cover large gaps in our knowledge of vegetation history, climate and human impact for the Lesser Caucasus. However, this lake was formed as the result of a large landslide, which necessitates investigation of erosion and recolonisation processes in the catchment area.Pollen and XRF analyses have been carried out on a core 5 meters in length which covers the last 3800 years.The basal age of the Kalavan sediment may approximate the age of the landslide, which would indicate a slope without vegetation cover, including the lake catchment area. Erosion and sedimentation processes produced at first coarse, heavy minerogenic elements, then erosion in the catchment area decreased due to the development of grass meadows, which led to a shift in the sedimentation. Throughout the stratigraphy, it is noteworthy that arboreal pollen increases due to the increasing presence of Quercus (oak), Carpinus orientalis (oriental hornbeam) and Fagus (beech), the last two being late invaders having a shade-tolerant ecology.These ecological processes had a major influence on the development of vegetation on Kalavan’s landslide, but this masks other long-term forcing factors such as climate change and human impact. Relating the vegetation and erosion histories of Kalavan to regional climate and archeological data was useful for their identification. The ancient arid phase (2000-1600 cal. BP), the Medieval Warm Period and the Little Ice Age affected the vegetation, while demography variations that occurred during the medieval period are demonstrated by the presence of pastoralism

Kites on the margin. The Aragats kites in Armenia

International audienc

Evolution de la végétation et du climat à Vanevan (rive sud-est du lac Sevan, Arménie) durant l'Holocène moyen

Communication à la Journée du "CReAAH", Archéologie, Archéosciences, Histoire, Rennes, 2 avril 201

The vegetation, climate, and fire history of a mountain steppe: A Holocene reconstruction from the South Caucasus, Shenkani, Armenia

International audienceSteppe and grassland ecosystems constitute important biomes that are influenced by multiple factors such as climate, human activity, and fire. Yet how these factors have influenced the plant composition of these biomes through time continues to be understudied. This paper investigates how these mechanisms have transformed the steppe landscape recorded at the mire site of Shenkani, Armenia. This highland site, located in the South Caucasus, has a long human history of permanent settlements near the core site starting at 5500 cal. BP. A variety of biological and geochemical proxies, including pollen, non-pollen palynomorphs, macro-charcoal, 14C age model, X-ray fluorescence, loss-of-ignition, magnetic susceptibility, and a quantitative climate reconstruction inferred from pollen, are utilized in this paper. We find that this area has remained a steppe with small stands of trees throughout the duration of the Holocene. Changes in steppe plant composition primarily occur between semi-desert steppes (Chenopodiaceae), grassland steppes (or Poaceae dominated meadow-steppes), and mixed steppes with forest patches. In this record, two phases of local grassland expansion occurred between 9500 and 7000 cal. BP and 2500–1000 cal. BP, which covaried with local fire events. These grassland steppes were sustained until tree encroachment led to a more mixed steppe landscape around 7000 cal. BP and again at 1000 cal. BP. Climate, primarily precipitation, is the main driver of this persistent steppe landscape and the plant compositional shifts within it. However, fire and human activities contributed to steppe maintenance

The 2014 seismic hazard model of the Middle East: overview and results

The Earthquake Model of Middle East (EMME) Project aimed to develop regional scale seismic hazard and risk models uniformly throughout a region extending from the Eastern Mediterranean in the west to the Himalayas in the east and from the Gulf of Oman in the south to the Greater Caucasus in the North; a region which has been continuously devastated by large earthquakes throughout the history. The 2014 Seismic Hazard Model of Middle East (EMME-SHM14) was developed with the contribution of several institutions from ten countries. The present paper summarizes the efforts towards building a homogeneous seismic hazard model of the region and highlights some of the main results of this model. An important aim of the project was to transparently communicate the data and methods used and to obtain reproducible results. By doing so, the use of the model and results will be accessible by a wide community, further support the mitigation of seismic risks in the region and facilitate future improvements to the seismic hazard model. To this end all data, results and methods used are made available through the web-portal of the European Facilities for Earthquake Hazard and Risk (www.efehr.org)