Permafrost, landscape and ecosystem responses to late Quaternary warm stages in Northeast Siberia

Permafrost, landscape and ecosystem responses to late Quaternary warm stages in Northeast Siberia S. Wetterich1, F. Kienast2, L. Schirrmeister1, M. Fritz1, A. Andreev3, P. Tarasov4 1Alfred Wegener Institute for Polar and Marine Research, Department of Periglacial Research, Potsdam, Germany; 2Senckenberg Research Institute and Natural History Museum, Research Station for Quaternary Palaeontology, Weimar, Germany; 3Institute of Geology and Mineralogy, University of Cologne, Germany; 4Institute of Geological Sciences, Free University Berlin, Germany Perennially frozen ground is widely distributed in Arctic lowlands and beyond. Permafrost responds sensitive to changes in climate conditions. Climate-driven dynamics of landscape, sedimentation and ecology in periglacial regions are frequently recorded in permafrost deposits. The study of late Quaternary permafrost can therefore reveal past glacial-interglacial and stadialinterstadial environmental dynamics. One of the most striking processes under warming climate conditions is the extensive thawing of permafrost (thermokarst) and subsequent surface subsidence. Thermokarst basins promote the development of lakes, whose sedimentological and paleontological records give insights into past interglacial and interstadial (warm). In this paper we present results of qualitative and quantitative reconstructions of climate and environmental conditions for the last Interglacial (MIS 5e, Kazantsevo; ca. 130 to 115 ka ago), the lateglacial Allerød Interstadial (ca. 13 to 11 uncal. ka BP), and the early Holocene (ca. 10.5 to 8 uncal. ka BP). The study was performed in course of the IPY project #15 ‘Past Permafrost’ with permafrost deposits exposed at the coasts of the Dmitry Laptev Strait (East Siberian Sea, East Siberia). The reconstruction based on fossil-rich findings of plants (pollen, macro-remains) and invertebrates (beetles, chironomids, ostracods gastropods). Interglacial vegetation dynamics are reflected in the pollen records by changes from early interglacial grass-sedge-tundra to shrub-tundra during the interglacial thermal optimum followed by grass-sedge-tundra vegetation at the end of the Kazantsevo warm period. Terrestrial beetle and plant remains prove the former existence of open forest tundra with Dahurian larch, grey alder and boreal shrubs interspersed with patches of steppes and meadows during the interglacial thermal optimum. Mean temperature reconstructions of the warmest month (MTWA, TJuly) for the interglacial thermal optimum are based on quantitative chironomid transfer functions revealed a TJuly of 12.9 ± 0.9 °C. The TJuly reconstructed by plant macrofossils amounts to 13.2 ± 0.5 °C, and the pollen-based TJuly reaches 14.3 ± 3.3 °C. Low net precipitation is reflected by steppe plants and beetles. The temperature reconstruction based on three independent approaches. Nethertheless, all methods consistently indicate an interglacial TJuly about 10 °C higher than today, which is interpreted as a result of a combination of increased insolation and higher climatic continentality during the last Interglacial. Grass-sedge dominated tundra vegetation occurred during the lateglacial to Holocene transition which was replaced by shrub tundra during the early Holocene. The presence of Salix and Betula pollen reflects temperatures about 4 °C higher than present between 12 to 11 uncal. ka BP, during the Allerød Interstadial, but shrubs disappeared in the following Younger Dryas stadial, reflecting a climate deterioration. Alnus fruticosa, Betula nana, Poaceae and Cyperaceae dominate early Holocene pollen spectra. Pollen-based reconstructions point to TJuly 4 °C warmer than present. Shrubs gradually disappeared from coastal areas after 7.6 uncal. ka BP when vegetation cover became similar to modern wet tundra. Thermokarst acted as response to warming conditions on landscape scale in permafrost regions. Concurrent changes in relief, hydrology and ecosystems are obvious and detectable by analyses of the paleontological record preserved in thermokarst deposits

Examining bias in pollen-based quantitative climate reconstructions induced by human impact on vegetation in China

Abstract. Human impact is a well-known confounder in pollen-based quantitative climate reconstructions as most terrestrial ecosystems have been artificially affected to varying degrees. In this paper, we use a "human-induced" pollen dataset (H-set) and a corresponding "natural" pollen dataset (N-set) to establish pollen–climate calibration sets for temperate eastern China (TEC). The two calibration sets, taking a weighted averaging partial least squares (WA-PLS) approach, are used to reconstruct past climate variables from a fossil record, which is located at the margin of the East Asian summer monsoon in north-central China and covers the late glacial Holocene from 14.7 ka BP (thousands of years before AD 1950). Ordination results suggest that mean annual precipitation (Pann) is the main explanatory variable of both pollen composition and percentage distributions in both datasets. The Pann reconstructions, based on the two calibration sets, demonstrate consistently similar patterns and general trends, suggesting a relatively strong climate impact on the regional vegetation and pollen spectra. However, our results also indicate that the human impact may obscure climate signals derived from fossil pollen assemblages. In a test with modern climate and pollen data, the Pann influence on pollen distribution decreases in the H-set, while the human influence index (HII) rises. Moreover, the relatively strong human impact reduces woody pollen taxa abundances, particularly in the subhumid forested areas. Consequently, this shifts their model-inferred Pann optima to the arid end of the gradient compared to Pann tolerances in the natural dataset and further produces distinct deviations when the total tree pollen percentages are high (i.e. about 40 % for the Gonghai area) in the fossil sequence. In summary, the calibration set with human impact used in our experiment can produce a reliable general pattern of past climate, but the human impact on vegetation affects the pollen–climate relationship and biases the pollen-based climate reconstruction. The extent of human-induced bias may be rather small for the entire late glacial and early Holocene interval when we use a reference set called natural. Nevertheless, this potential bias should be kept in mind when conducting quantitative reconstructions, especially for the recent 2 or 3 millennia

Identification and quantification of cannabinol as a biomarker for local hemp retting in an ancient sedimentary record by HPTLC-ESI-MS

Cannabis products have been used in various fields of everyday life for many centuries, and applications in folk medicine and textile production have been well-known for many centuries. For traditional textile production, hemp fibers were extracted from the stems by water retting in stagnant or slow-moving waters. During this procedure, parts of the plant material‚ among them phytocannabinoids‚ are released into the water. Cannabinol (CBN) is an important degradation product of the predominant phytocannabinoids found in Cannabis species. Thus, it is an excellent indicator for present as well as ancient hemp water retting. In this study, we developed and validated a simple and fast method for the determination of CBN in sediment samples using high-performance thin-layer chromatography (HPTLC) combined with electrospray ionization mass spectrometry (ESI-MS), thereby testing different extraction and cleanup procedures‚ as well as various sorbents and solvents for planar chromatography. This method shows a satisfactory overall analytical performance with an average recovery rate of 73%. Our protocol enabled qualitative and quantitative analyses of CBN in samples of a bottom sediment core‚ having been obtained from a small lake in Northern India, where intense local retting of hemp was suggested in the past. The analyses showed a maximum CBN content in pollen zone 4 covering a depth range of 262–209 cm, dating from approximately 480 BCE to 1050 CE. These findings correlate with existing records of Cannabis-type pollen. Thus, the method we propose is a helpful tool to track ancient hemp retting activities

Postglacial Development of Kazakhstan Pine Forests

Fossil pollen records from two peatlands and two lakes in Kazakhstan provide radiocarbon-dated evidence of vegetation change since 13 000 BP. During the Lateglacial open spruce (Picea obovata) forests started spreading along river valleys and over the Kazakhstan Foothills. By 9500 BP, the southern limit of spruce approached its present-day position. Between 9500 and 8000 BP steppe and open birch forests formed the vegetation in the south of the West Siberian Lowland. Dry steppe and semi-desert were the main types of vegetation in north Kazakhstan. From 7000 to 5500 BP Scots pine (Pinus sylvestris L.) expanded in Kazakhstan and reached its present day southern limit. Since 5500 BP pine has formed monospecific forests in the lrtysh-Semipalatinsk area and in the northern part of the Kazakhstan Foothills. By 5000 BP lime (Tilia cordata) penetrated into the northern part of the Kazakhstan Foothills. The ranges of oak (Quercus robur), elm (Ulmus glabra) and black alder (AInus glutinosa) also expanded. The period 4500-3600 BP was characterised by a drier and more continental climate. During that time, the forested area decreased. The ranges of broadleaved trees and alder were reduced. A phase of less continental climate occurred 3300-2800/ 2700 BP. By 1500 BP the present southern limit of Scots pine was established.Les données palynologiques de quatre stations au Kazakhstan ont permis de reconstituer l'histoire de la végétation depuis 13 000 BP. Au Tardiglaciaire, des pessières claires à Picea obovata ont commencé à occuper les vallées des fleuves et les collines de Kazakhs. Vers 9500 BP la limite méridionale moderne de Picea obovata fut atteinte. Entre 9500-8000 BP les steppes et forêts claires de bouleaux (Betula alba) étaient répandues au sud de la Sibérie occidentale. Des steppes sèches et des semi-déserts constituaient alors la végétation du nord du Kazakhstan. Entre 7000 et 5500 BP, le pin sylvestre (Pinus sylvestris) s'est répandu au Kazakhstan jusqu'à sa limite méridionale actuelle. Depuis 5500 BP, Ie pin a constitué des forêts monospécifiques dans la région de Semipalatinsk-lrtysh et dans la partie septentrionale des collines de Kazakhs. Vers 5000 BP. Ie tilleul (Tilia cordata) fut présent dans la partie septentrionale des collines de Kazakhs. Les aires du chêne (Quercus robur), de l'orme (Ulmus glabra) et de l'aulne (AInus glutinosa) se sont étendues. Entre 4500 et 3600 BP, le climat est devenu plus sec et plus continental. L'aire de peuplement des forêts a diminué. La répartition des arbres aux larges feuilles et de l'aulne ont diminué. Un climat moins continental s'est instauré entre 3300 et 2800/2700 BP. Vers 1500 BP, la limite méridionale actuelle du pin s'est établie.Fossile Pollen-Belege von zwei Torfmooren und zwei Seen in Kasachstan liefern mittels Kohlenstoffdatierung den Nachweis einer Vegetationverànderung seit 13 000 v.u.Z. Im Spâtglazial begannen offene Fichtenwâlder (Picea obovata) sich entlang der Flusstâler und ùber die Gebirgsauslâufer Kasachstans auszubreiten. Um 9500 v.u.Z. bildeten Steppen und offene Birkenwàlder die Vegetation im Sùden des westsibirischen Tieflands. Trockene Steppen und Halbwùsten waren die hauptsàchlichen Vegetationstypen in Nord-Kasachstan. Von 7000 bis 5500 v.u.Z. breitete sich die Fôhre (Pinus silvestris L) in Kasachstan aus und erreichte ihre heutige sùdliche Grenze. Seit 5500 v.u.Z. hat die Kiefer monospezifische Wàlder im Irtysh-Semipalatinsk-Gebiet und im nôrdlichen Teil der Gebirgsauslâufer Kasachstans gebildet. Um 5000 v.u.Z. drang die Linde (Tilia cordata) in den nôrdlichen Teil der Gebirgsauslâufer Kasachstans ein. Die Ausdehnung von Eiche (Quercus robur), Ulme (Ulmus glabra) und Schwarzerle (AInus glutinosa) nahm auch zu. Die Zeit von 4500 - 3600 v.u.Z. zeichnete sich durch ein trockeneres und mehr kontinentales Klima aus. Wâhrend dieser Zeit nahm die bewaldete Zone ab. Das Vorkommen von grossblâttrigen Bàumen und Erlen nahm ab. Eine Phase weniger kontinentalen Klimas trat zwischen 3300 - 2800/2700 v.u.Z. ein. Um 1500 v.u.Z. war die gegenwârtige sùdliche Grenze der Fôhre etabliert

Internet Voting Using Zcash

Voting systems have been around for hundreds of years and despite different views on their integrity, have always been deemed secure with some fundamental security and anonymity principles. Numerous electronic systems have been proposed and implemented but some suspicion has been raised regarding the integrity of elections due to detected security vulnerabilities within these systems. Electronic voting, to be successful, requires a more transparent and secure approach, than is offered by current protocols. The approach presented in this paper involves a protocol developed on blockchain technology. The underlying technology used in the voting system is a payment scheme, which offers anonymity of transactions, a trait not seen in blockchain protocols to date. The proposed protocol offers anonymity of voter transactions, while keeping the transactions private, and the election transparent and secure. The underlying payment protocol has not been modified in any way, the voting protocol merely offers an alternative use case

Introduction to the Special Issue: "Introduction and intensification of agriculture in Central Eurasia and adjacent regions"

For well over a century, scholars from across the social and biological sciences have been trying to understand the origins and spread of agriculture. This debate is often intertwined with discussions of climate change and human environmental impact. Over the past decade, this debate has spread into Central Eurasia, from western China to Ukraine and southern Russia to Turkmenistan, a part of the world often thought to have been largely dominated by pastoralists. A growing interest in the prehistory of Central Eurasia has spurred a new chapter in the origins of agriculture debate; archaeobotanical research is showing how important farming practices in this region were in regard to the spread of crops across the Old World. While early people living in Central Eurasia played an influential role in shaping human history, there is still limited understanding of the trajectories of social evolution among these populations. In March 2015, 30 leading scholars from around the globe came together in Berlin, Germany, to discuss the introduction and intensification of agriculture in Central Eurasia and adjacent regions. At the German Archaeological Institute in Berlin (Deutsches Archäologisches Institut, DAI), these scholars presented novel data on topics covering East, South, and Central Asia, spanning a wide realm of methodological approaches. The present special edition volume deals with a selection of the papers given at this conference, and it marks a significant step toward recognizing the contribution of Central Eurasian populations in the spread and development of agricultural systems over the course of the Holocene

Eurasian perspective

Reproducing the tree cover changes throughout the Holocene is a challenge for land surface–atmosphere models. Here, results of a transient Holocene simulation of the coupled climate–carbon cycle model, CLIMBER2-LPJ, driven by changes in orbital forcing, are compared with pollen data and pollen-based reconstructions for several regions of Eurasia in terms of changes in tree fraction. The decline in tree fraction in the high latitudes suggested by data and model simulations is driven by a decrease in summer temperature over the Holocene. The cooler and drier trend at the eastern side of the Eurasian continent, in Mongolia and China, also led to a decrease in tree cover in both model and data. In contrast, the Holocene trend towards a cooler climate in the continental interior (Kazakhstan) is accompanied by an increase in woody cover. There a relatively small reduction in precipitation was likely compensated by lower evapotranspiration in comparison to the monsoon-affected regions. In general the model-data comparison demonstrates that climate-driven changes during the Holocene result in a non-homogeneous pattern of tree cover change across the Eurasian continent. For the Eifel region in Germany, the model suggests a relatively moist and cool climate and dense tree cover. The Holzmaar pollen record agrees with the model for the intervals 8–3 ka and 1.7–1.3 ka BP, but suggests great reduction of the tree cover 3–2 ka and after 1.3 ka BP, when highly developed settlements and agriculture spread in the region

Pollen- and charcoal-based evidence for climatic and human impact on vegetation in the northern edge of Wuyi Mountains, China, during the last 8200 years

Pollen and charcoal records derived from the sediment core of Lantianyan (LTY) peat bog, Northern Wuyi Mountain chains, eastern subtropical China, provide valuable information of landscape evolution caused by both climatic variation and anthropogenic activities over the past 8200 years. Our results reveal fluvial and lacustrine deposition between c. 8200 and 5600 cal. yr BP. The high proportion of pollen from evergreen broadleaved forests (e.g. Quercus and Castanopsis) and Alnus trees, a taxon frequently occurring in mountain wetlands, implies a humid interval, which is consistent with the Holocene moisture maximum in eastern China. After 5600 cal. yr BP, the spread of the wooded swamp taxon, Glyptostrobus, suggests shallow water conditions and peat formation caused by gradual drying. The drying trend generally corresponds with the speleothem isotope record from this region, revealing a weakening East Asian summer monsoon (EASM) due to a decrease in Northern Hemisphere summer insolation (and in air temperature). Peaks in the abundance and concentration of Glyptostrobus pollen at c. 4600–4400 cal. yr BP and c. 3300–3000 cal. yr BP suggest two periods of swamp expansions, which coincide with the drought intervals revealed by the speleothem records. The LTY pollen and charcoal record demonstrates that human-induced land cover change was negligible before 3600 cal. yr BP. We consider the first signal of intensive human activity and landscape clearing to be the noticeable increase in charcoal particles at around 3600 cal. yr BP. This anthropogenic impact is followed by a dramatic decrease in arboreal pollen and increase in Poaceae pollen percentages, likely reflecting a transition to rice-paddy agriculture in the study area

An overview

A total of 51,074 archaeological sites from the early Neolithic to the early Iron Age (c. 8000–500 BC), with a spatial extent covering most regions of China (c. 73–131°E and c. 20–53°N), were analysed over space and time in this study. Site maps of 25 Chinese provinces, autonomous regions and municipalities, published in the series ‘Atlas of Chinese Cultural Relics’, were used to extract, digitalise and correlate its archaeological data. The data were, in turn, entered into a database using a self-developed mapping software that makes the data, in a dynamic way, analysable as a contribution to various scientific questions, such as population growth and migrations, spread of agriculture and changes in subsistence strategies. The results clearly show asynchronous patterns of changes between the northern and southern parts of China (i.e. north and south of the Yangtze River, respectively) but also within these macro-regions. In the northern part of China (i.e. along the Yellow River and its tributaries and in the Xiliao River basin), the first noticeable increase in the concentration of Neolithic sites occurred between c. 5000 and 4000 BC; however, highest site concentrations were reached between c. 2000 and 500 BC. Our analysis shows a radical north- eastern shift of high site-density clusters (over 50 sites per 100 × 100 km grid cell) from the Wei and middle/lower Yellow Rivers to the Liao River system sometime between 2350 BC and 1750 BC. This shift is hypothetically discussed in the context of the incorporation of West Asian domesticated animals and plants into the existing northern Chinese agricultural system. In the southern part of China, archaeological sites do not show a noticeable increase in the absolute number of sites until after c. 1500 BC, reaching a maximum around 1000 BC