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Mid-late Holocene pollen evidence from the Ispani-II Sphagnum bog in lowland Western Georgia shows that 4500 years ago Castanea (chestnut)-dominated woods rapidly declined to be replaced by alder swamps and, later, during the first millennium bc, by open, marshy landscapes in which fire played a prominent part. Around 1900 years ago, Sphagnum blank...
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Context 1
... and stan- dard acetolysis (Moore et al., 1991). The presence of Alnus and Poaceae macrofossils in the sediment core (Table 1) suggested that they were locally occurring at the time of pollen deposition, so we have excluded these taxa from the dryland pollen sum. However, because Alnus occurs in mixed Colchic forests as well as in marshes and Poaceae also includes many terrestrial types, we account for this in the discussion below. ...
Context 2
... lithological units can be identified in the Ispani-II sediments (Table 1). The lowermost unit (Is-1: 950 Á690 cm) consists of clay-rich sediments, containing both sandy and organic layers, charcoal and macrofossils (Table 1). ...
Context 3
... lithological units can be identified in the Ispani-II sediments (Table 1). The lowermost unit (Is-1: 950 Á690 cm) consists of clay-rich sediments, containing both sandy and organic layers, charcoal and macrofossils (Table 1). Its organic content varies between 9% and 23% ( Figure 3). ...
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... Human impact was significant along the western Black Sea coast as reflected in pollen diagrams from the Bulgarian Black Sea coastal lakes (Todorova 1986;Bozilova and Filipova 1991;Bozilova and Beug 1994). Terrestrial pollen records from the eastern Black Sea coast reveal anthropogenic impact starting at 4000 14 C yrs BP (Connor et al. 2007). ...
Multi-proxy analysis (spore-pollen, dinoflagellate cysts, other non-pollen palynomorphs (NPPs), radiocarbon dating and lithology) was performed on marine sediments from three new cores retrieved during the two cruise expeditions on board the Research Vessel “Akademik” in 2009 and 2011. The Varna transect comprises three cores extending from the outer shelf, continental slope and deep-water zone. The record spans the last 26000 years (all ages obtained in this study are given in calendar years BP (cal. yrs BP)). The pollen record reveals the spreading of steppe vegetation dominated by Artemisia and Chenopodiaceae, suggesting cold and dry environments during the Late Pleniglacial – Oldest Dryas (25903–15612 cal. yrs BP). Stands of Pinus and Quercus reflect warming/humidity increase during the melting pulses (19.2–14.5 cal. ka BP) and the Late Glacial interstadials Bølling and Allerød. The Younger Dryas (13257–11788 cal. yrs BP) coldest and driest environments are clearly demonstrated by the maximum relative abundance of Artemisia and Chenopodiaceae. During the Early Holocene (Preboreal and Boreal chronozones, 11788–8004 cal. yrs BP), Quercus appeared as a pioneer species and, along with other temperate deciduous arboreal taxa, formed open deciduous forests as a response to the increased temperature. The rapid expansion of these taxa indicates that they survived in Glacial refugia in the coastal mountains. During the Atlantic chronozone (8004–5483 cal. yrs BP), optimal climate conditions (high humidity and increased mean annual temperatures) stimulated the establishment of species-rich mixed temperate deciduous forests. During the Subboreal chronozone (5483–2837 cal. yrs BP), Carpinus betulus and Fagus expanded simultaneously and became more important components of mixed oak forests and probably also formed separate communities. During the Subatlantic chronozone (2837 cal. yrs BP to pre-industrial time), climate-driven changes (an increase of humidity and a cooling of the climate) appear to be the main drivers of the specific vegetation succession expressed by increased abundance of Alnus, Fraxinus excelsior and Salix along with lianas, suggesting formation of flooded riparian forests (so called ‘Longoz’) lining the river valleys along the Black Sea coast. The first indicators of farming and other human activities have been recorded since 7074 cal. yrs BP. The dinoflagellate cyst (dinocyst) assemblages have been analysed to assess the changes in the Black Sea environment over the last 26000 years in terms of fluctuation in paleoproduction and surface water conditions related to changes in climate, freshwater input and Mediterranean water intrusion. Two major dinocyst assemblages were distinguished: one dominated by stenohaline freshwater/brackish-water species and a successive one dominated by euryhaline marine species. The changes in the composition of the assemblages occurred at 7668 cal. yrs BP. The abrupt decrease of stenohaline freshwater/brackish-water species Pyxidinopsis psilata and Spiniferites cruciformis was followed upwards by a gradual increase in euryhaline marine species, such as Lingulodinium machaerophorum, Spiniferites belerius, S. bentorii and acritarch Cymatiosphaera globulosa. The first occurrence of euryhaline marine species took place synchronously with the onset of sapropel deposition. Modern marine conditions were established after 6417 cal yrs BP when an abundance of Mediterranean-related species, such as Operculodinium centrocarpum and Spiniferites mirabilis, along with other heterotrophic species, occurred. After the stable cold and dry environment during the Last Glacial Maximum, the phytoplankton record of core AKAD 11-17 shows that Pediastrum boryanum var. boryanum has a cyclical abundance associated with the deposition of four red-brown clay layers between 19.2 and 14.5 cal. ka BP. This event is associated with the major melting phase of European Ice drained by the Danube and Dnieper Rivers in response to climate warming observed after the end of the Last Glacial Maximum. During the Early Holocene, P. psilata, characterised by a preference to warmer temperatures, demonstrates its ecological optimum for growth concerning SST reaching maximum relative abundance of 94% between 11072 and 8638 cal. yrs BP. This maximum was interrupted by an abrupt significant short-term decrease in the relative abundance of P. psilata centred between 8500 and 8300 cal. yrs BP reflecting cold conditions similar to those of Younger Dryas. This finding, also confirmed by the rapid significant decrease of arboreal pollen, particularly of Quercus in the same studied core, is considered a regional expression of the well-known ‘8.2 ka cold event’ which is commonly linked to a meltwater-related perturbation of the Atlantic Meridional Overturning Circulation (AMOC) and associated collapse of oceanic northward heat transport. Our fossil pollen and dinocyst data confirm that the high amplitude temperature anomaly associated with ‘the 8.2 ka cold event’ may have also occurred in south-eastern Europe, at lower latitudes of the western Black Sea coastal area, most probably due to atmospheric transition and/or river discharge.
... The light blue line shows the timing of the appearance of Arbutus in each region. glacial refugium for thermophilic species, such as Ilex colchica, Hedera colchica, Quercus pontica, Betula medwedewii, Corylus colchica, and Buxus colchica (Denk et al., 2001;Connor et al., 2007;Melia et al., 2012). In this district, Arbutus occurs in coastal enclaves under a para-Mediterranean climate, relatively humid, nearly frost-free, and with low seasonal fluctuations, similar to the Atlantic climatic regime. ...
... The vegetation benefits from annually warm average temperatures and a humid climate with high precipitation (>2000 mm/a) (Box et al., 2000;Hijmans et al., 2005). Based on pollen records taken from southern parts of the Colchian plain, species-rich open wetland forests (e.g., Zelkova and Castanea forests) are indicated for the time of the mounds' foundation in the early second millennium B.C. (Connor et al., 2007;de Klerk et al., 2009;Kvavadze & Connor, 2005;Shatilova et al., 2010). This is especially the case for the climate optimum between 1850 and 400 B.C., pollen data implies a predominance of warm and humid conditions, covering the heyday of the Colchian culture as well as the time of the ...
... Archaeological findings clearly show that the Kolkheti lowlands have been quite densely settled since the Early Bronze Age. The oldest known settlements in the Kolkheti lowlands are Ispani (Connor et al., 2007;de Klerk et al., 2009;Papuashvili & Papuashvili, 2014), located north of the town of Kobuleti, and Ontskoshia (Janelidze & Tatashidze, 2010), close to the town of Anaklia in the vicinity of the river mouth of the Enguri. They were radiocarbon-dated to the late fourth to mid-third millennium B.C., that is, the transition between the Chalcolithic and the Early Bronze Age in this region (Lordkipanidze, 1991). ...
Along the lower course of the Rioni and several minor rivers, more than 70 settlement mounds (local name: Dikhagudzuba ) have been identified by field surveys and remote sensing techniques. They give evidence of a formerly densely populated landscape in the coastal lowlands on the Colchian plain (western Georgia) and have been dated to the Bronze Age. As yet, limited information is available on their internal architecture, the chronology of the different layers and their palaeoenvironmental context. Based on archaeological sources, remote sensing measurements of three mounds and sediment cores from one mound and its closer surroundings, our study presents a review of the relevant literature and reveals the internal structure, distribution and spatial extent of the mounds. Geochemical and sedimentological analyses of element contents (X‐ray fluorescence) and granulometry helped to identify different stratigraphical layers and differentiate between natural facies and anthropogenic deposits; using the Structure‐from‐Motion technique the mounds' dimensions were calculated. The studied settlement mounds had relatively small dimension (varying from 30 to 100 m in diameter) and were similar in their stratigraphy. Measurement of elements that can identify types of human activity, notably metals and phosphorus, suggest changing intensities of human occupation, pastoral agriculture and metalworking through the occupation sequence. According to the ¹⁴ C chronology, the formation of the settlements occurred during the first half of the second millennium B.C., which confirms the archaeological interpretation of their Bronze Age origin. The narrow age difference between the lowermost and uppermost anthropogenic layers indicates an intentional construction of the mounds, rather than a successive accumulation of construction debris due to the disintegration of loam bricks by weathering. Therefore, they are indeed mounds and not tells . It is most likely that the characteristic circular moats that surround them were the source of their construction material. Fluvial and alluvial processes in a warm and humid climate dominated the environment of the mounds.
... It also should be noted that the archaeological material and geological cross-sections of the Holocene period in Georgia have been fairly well studied palynologically. Investigations have revealed that during all climatic optimums so far studied, especially in the Bronze Age, in Western Georgia the chestnut forest distribution area expanded, occupying the lower and middle parts (foot and hillside) of the mountains (Arabuli et al., 2007;Connor et al., 2007;Denk et al., 2001;Connor and Kvavadze 2008;Kvavadze and Connor 2005;Kvavadze and Bilanishvili, 2015). Along with chestnut, the presence of such thermophilic taxa as zelkva, hornbeam, lime and oak, increases as well. ...
This article focuses on the palynological (pollen and non-pollen palynomorphs) study of material found with artefacts from Late Bronze Age archaeometallurgical sites in the Lechkhumi area of the mountainous south-west Caucasus region of ancient Colchis. The analysis of organic residues recovered from voids in slag and crucible fragments have revealed an abundance of pollen and spores of diverse plant taxa. Many non-palynological palynomorphs were also found. In total, more than 50 palynomorphs were identified. It was observed that the chemical composition of the copper smelting slag fragments has contributed to the good preservation of the pollen grains, though detailed chemical analyses and experiments are needed. The spectrum from slag includes taxa that are more poorly preserved in sediments, including soil. This preservation undoubtedly makes palynological research of slag residues promising in the future. The range of fossilized plants and spores recovered proves that during the Late Bronze Age in Lechkhumi, forests dominated by chestnut (Castanea sativa) occupied a much larger area than today. Other thermophilic trees, such as zelkva (Zelkova carpinifolia), oak (Quercus), lime (Tilia), and hornbeam (Carpinus betulus) were also present. Thermophilic ferns thrived in the undergrowth as well. In the 13th–9th centuries BC, the existence of warmer climatic conditions in Lechkhumi compared to that we have now is additionally confirmed by the presence of freshwater thermophilic algae Pseudoschizaea, Spirogyra and other Zygnemataceae found in the spectra. Spores of bracken fern (Pteridium aquilinum) and fungus Ustulina most probably reflect felling and human exploitation of the woodland in the close neighbourhood of the site. Comparison of palynological and wood charcoal analyses has demonstrated that the metallurgists of that time used the nearby woods as a source of fuel. Thanks to favourable climatic conditions, beside copper smelting some small-scale agricultural activities were performed which was visible in the composition of herbaceous plant taxa.
... Furthermore, there is evidence for widespread co-occurrence of areas with prolonged drought and with periods of increased precipitation between 1050 and 650 cal BP (Bradley et al., 2003). A similar decline in values of PTEROCARYA FRAXINIFOLIA pollen has been frequently found in pollen diagrams from central-northern Iran (Khakpour Saeej et al., 2013;Ramezani et al., 2008Ramezani et al., , 2016Ramezani et al., , 2023Ramezani, 2013), the regions south-east of the Caspian Sea (Leroy et al., 2013a), and western Georgia (Kvavadze, 1982;Connor et al., 2007;de Klerk et al., 2009), but with dates that differ some centuries. This event has been tentatively correlated to a cooling/drying climate (Connor, 2011;De Klerk et al., 2009;Ramezani et al., 2008Ramezani et al., , 2016Ramezani et al., , 2023Leroy et al., 2013a). ...
The Hyrcanian region is a biogeographic entity of high biodiversity and a centre of Arcto-Tertiary relict flora. A pollen record from the mid-elevation of the Alborz Mountains (northern Iran) reaching back to 20,000 cal BP
reveals the Late Quaternary vegetation history of this globally important forest ecosystem. For the period
20,000–14,419 cal BP the pollen record indicates the presence of beech, oak, and birch associated with elm and
hornbeam, which indicates the presence of a Weichselian refugium for deciduous tree species. The simultaneous
presence of abundant pollen attributable to Artemisia, Amaranthaceae, Apiaceae, and Hippopha¨e rhamnoides
suggests the presence of a dry and cold steppe environment at higher elevations. For the period 16,746–14,419
cal BP, the pollen record indicates a steppe vegetation around the studied peatland (with a predominance of
Artemisia, Amaranthaceae and Apiaceae species, along with Eremurus), a slight expansion of oak, and a strong
decrease of beech. The period 14,419–12,993 cal BP started with a substantial rise in the values of pollen
attributable to Quercus, Carpinus, and Ulmus with the near absence of pollen of dry-growing herbaceous vegetation.
For 12,993–11,745 cal BP, a drastic decline of arboreal pollen types, pronounced peaks of NAP types, and
constant values of pollen of Ephedra persuasively point to a dry period in the studied region. Towards the end of
this period, when the climate apparently became somewhat warmer, deciduous trees expanded around the study
site earlier than in other regions, probably because of the site’s proximity to the refugium. After 8600 cal BP, oak
declined in importance whereas beech and hornbeam expanded, showing the establishment of the contemporary
temperate climate and vegetation. A pronounced expansion of alder and wingnut took place around 4000 cal BP.
A remarkable decline of Pterocarya pollen at 1060 cal BP may relate to human impact and/or a cooling/drying
climate.
... It also grows sporadically in the margins of mires up to 1400 m asl (as is the case at the KHL site). A rather well-defined Pterocarya decline has been registered for the periods 1000-800 cal BP in pollen diagrams from central-northern Iran (Khakpour Saeej et al., 2014;Ramezani et al., 2008Ramezani et al., , 2016Ramezani, 2013), the south-eastern Caspian Sea lowlands (Leroy et al., 2013), and western Georgia (Connor et al., 2007;De Klerk et al., 2009;Kvavadze, 1982in Connor, 2011. For unknown reasons, the decline in the KHL record is delayed by ca. ...
... Therefore, besides substantial variations of human activity this also suggests different environmental and hydrological conditions in this region during the past. However, unlike the well-studied humid western Caucasian lowlands and regions >1,000 m a.s.l. in the Lesser Caucasus mountain range (Connor and Sagona, 2007a;Connor et al., 2007b;Messager et al., 2013;Joannin et al., 2014;Connor et al., 2018), existing studies from the lower-altitude semi-humid to semi-arid south-eastern Caucasus region are limited to scattered pollen records with generally rather poor chronostratigraphic control (Gogichaishvili, 1984;Connor and Kvavadze, 2008), or to fluvial-geomorphological (Ollivier et al.,FIGURE 1 The Caucasus region with the distribution of Late Bronze/Early Iron Age cultures (Sagona, 2018). The Shiraki Plain is shown with a red rectangle, and the Udabno region with similar ecologic and climatic conditions as well as a similar prehistoric settlement history with a red star. ...
Long-term human-environmental interactions in naturally fragile drylands are a focus of geomorphological and geoarchaeological research. Furthermore, many dryland societies were also affected by seismic activity. The semi-arid Shiraki Plain in the tectonically active southeastern Caucasus is currently covered by steppe and largely devoid of settlements. However, numerous Late Bronze to Early Iron Age city-type settlements suggest early state formation between ca. 3.2-2.5 ka that abruptly ended after that time. A paleolake was postulated for the lowest plain, and nearby pollen records suggest forest clearcutting of the upper altitudes under a more humid climate during the Late Bronze/Early Iron Ages. Furthermore, also an impact of earthquakes on regional Early Iron Age settlements was suggested. However, regional paleoenvironmental changes and paleoseismicity were not systematically studied so far. We combined geomorphological, sedimentological, chronological and paleoecological data with hydrological modelling to reconstruct regional Holocene paleoenvironmental changes, to identify natural and human causes and to study possible seismic events during the Late Bronze/Early Iron Ages. Our results show a balanced to negative Early to Mid-Holocene water balance probably caused by forested upper slopes. Hence, no lake but a pellic Vertisol developed in the lowest plain. Following, Late Bronze/Early Iron Age forest clear-cutting caused lake formation and the deposition of lacustrine sediments derived from soil erosion. Subsequently, regional aridification caused slow lake desiccation. Remains of freshwater fishes indicate that the lake potentially offered valuable ecosystem services for regional prehistoric societies even during the desiccation period. Finally, colluvial coverage of the lake sediments during the last centuries could have been linked with hydrological extremes during the Little Ice Age. Our study demonstrates that the Holocene hydrological balance of the Shiraki Plain was and is situated near a major hydrological threshold, making the landscape very sensitive to small-scale human or natural influences with severe consequences for local societies. Furthermore, seismites in the studied sediments do not indicate an influence of earthquakes on the main and late phases of Late Bronze/Early Iron Age settlement. Altogether, our study underlines the high value of multi-disciplinary approaches to investigate human-environmental interactions and paleoseismicity in drylands on millennial to centennial time scales.
... Charcoal concentration is a good indicator of the intensity of paleofire events, including both natural fires and human activities [36][37][38]. The transmission distance of charcoal is strongly associated with its particle size. ...
The timing and motivation of prehistoric human expansion into the hinterland of the Tibetan Plateau (TP) is a widely debated scientific issue. Recent archaeological studies have brought forward predictions of the earliest human occupation of the TP to the late–Middle Pleistocene. However, massive human occupation of the TP did not appear until the termination of the Last Glacial Maximum (LGM). The spatio-temporal distribution of prehistoric hunter-gatherers on the TP varies significantly before the permanent occupation after 3600 BP (before present). Here, we report on environmental-archaeological evidence from the Canxionggashuo (CXGS) site in Yushu Prefecture, which provides information that is key to understanding the dynamics of post-LGM human occupation on the TP. Radiocarbon dating has revealed two occupation periods of the CXGS site at 8600–7100 cal (calibrated years) BP and 2400–2100 cal BP. The charcoal concentration in cultural layers correlates well with paleo–human activities. Hunter-gatherers expanded westwards from the northeastern margin of the TP to the hinterland of the TP during the warming period of the early–middle Holocene (~11,500–6000 BP). However, these groups retreated during the middle–late Holocene (~6000–3600 BP) under a cooling-drying climate. Prehistoric humans finally occupied the hinterland of the TP permanently after 3600 BP, with an enhanced cold-adaptive lifestyle, although the climate was still deteriorating.
... To solve these tasks, we will use several methods. Essential are vibracore drillings with open and closed tubes in the different geoarchives; OSL-dating will be carried out on the large beach barrier of Poti; 14-C age estimates of organic matter from the cores will clarify the chronostratigraphy of the sedimentological processes; palynological analyses on the peat bogs of the Rioni plain will be done to get a better impression of the landscape evolution in space and time (see also Connor et al., 2007;de Klerk et al., 2009). Moreover, possible sites of the not yet discovered Greek and Roman city of Phasis should be identified by comparing philological with geoscientific data. ...
... Charcoal is an ideal indicator of climate change and human activities (Cao et al., 2007;Luo et al., 2006;Miao et al., 2017). Especially during the Holocene, the fluctuations in charcoal concentration in sediment generally reflect human fire events (Connor et al., 2007;Innes et al., 2009;Li et al., 2010). In this study, we found that the TCC increased dramatically during the period ~5.8-5.2 ka BP, indicating that prehistoric humans used fire frequently in the lake basin (Figure 7). ...
Lake Donggi Cona is a key area for the exploration of the prehistoric settlement of the inner Tibetan Plateau because of its location in the joint of the higher inner Tibetan Plateau and the upper Yellow River valley. Here, we carried out archeological investigation on the lake basin, and a total of 256 pieces of stone artifacts were collected from the surface of the DJCN 3-2-2 site on the northern shore terraces of the lake. In addition, AMS14C and OSL dating were performed on hearths and section (DJCN 3-2-2), respectively; meanwhile environmental proxies, including grain size, charcoal, magnetic susceptibility, fungal spore, and pollen, were analyzed. The results indicate that the AMS14C ages of the charcoal range between ~5.4 and 5.0 cal. ka BP, consistent with
OSL dating from the charcoal layers in the DJCN 3-2-2 section (~5.5 ka BP). The functional analysis of the stone artifacts and dating results showed that the site was a seasonal, relative long-term, and central camp which was used for processing of stone artifacts, cutting and consuming food and the production of daily necessities. Charcoal, magnetic susceptibility, and fungal spores from the DJCN 3-2-2 section revealed that prehistoric human activities began at ~5.8 ka BP and significantly intensified during the period of ~5.6–5.5 ka BP and then gradually weakened. Pollen assemblages indicated that the vegetation was dominated by alpine steppe during the period of ~5.8–5.0ka BP, indicative of a relatively warmer and wetter climatic condition during this period. Taken
together, we infer that under the impact of the Neolithic culture in lower altitude of upper Yellow River valley and Microlithic culture in the higher altitude inner Plateau, a Neolithic-Zongri culture had emerged in the transitional region between these two cultures during middle Holocene.
