ALBERT

Description / Table of Contents: Weniger als 25 Jahre geben Forscher*innen ihm noch, dann wird es soweit sein: Bis 2050 wird das Eis der Arktis abschmelzen, und unser Planet, den Generationen nur mit von ewigem Eis bedeckten Polkappen kennen, wird sich für immer verändern. Welche Folgen wird das Schwinden des Eises für die Menschheit haben? Wie wirkt es sich auf das Klima, die Meere und unser Wetter aus? Wer den Klimawandel wirklich verstehen will, sollte den Blick auf die Polarregionen richten, um zu erkennen, was sie für unser Klima in Mitteleuropa bedeuten und wie sie sich und damit auch unseren Alltag verändern. Stefanie Arndt lässt ihre Leser*innen die entlegensten Regionen dieser Erde durch ihre Augen sehen. Sie erzählt von den tiefgreifenden Veränderungen, die sie auf ihren Expeditionen mit der Polarstern beobachten konnte, von ihrer Arbeit als Polarforscherin und von der zarten Schönheit eines schwindenden Lebensraums. Was so fern scheint, rückt plötzlich ganz nahe: Können wir die unumkehrbaren Auswirkungen, die ein Abschmelzen der Polkappen nach sich zöge, noch aufhalten? Und wenn ja: Wie?

Description / Table of Contents: В докладах и сообщениях VII выпуска освещается широкий круг вопросов инженерной геокриологии - методы и опыт промышленно-гражданского строительства на вечномерзлых грунтах, методы регулирования термического режима и направленного изменения механических свойств мерзлых грунтов, используемых в качестве оснований и материалов сооружений тепловое и механическое взаимодеиствие сооружении или отдельных конструкций с мерзлыми, промерзающими или оттаивающими грунтами методы теплотехнических расчетов, эффективные способы фундаментостроения на мерзлых грунтах, влияние геокриологических условии на производство горных работ, вопросы гидротехнического строительства на вечномерзлых грунтах в суровых климатических условиях, выбор оптимального варианта трассы и способы прокладки магистральных газопроводов, принципы проектирования и строительства дорог на вечномерзлых грунтах и некоторые другие частные вопросы.

Description / Table of Contents: Translation of the abstract: The reports and messages of the VII issue cover a wide range of issues of engineering geocryology - methods and experience of industrial and civil construction on permafrost soils, methods for regulating the thermal regime and directed changes in the mechanical properties of frozen soils used as foundations and materials for structures thermal and mechanical interaction of a structure or individual structures with frozen, freezing or thawing soils methods of thermal engineering calculations, effective methods of foundation construction on frozen soils, the impact of geocryological conditions on mining operations, issues of hydraulic engineering construction on permafrost soils in harsh climatic conditions, the choice of the optimal route option and methods for laying main gas pipelines, design principles and construction of roads on permafrost soils and some other particular issues.

Description / Table of Contents: The deciduous needle tree larch (Larix Mill.) covers more than 80% of the Asian boreal forests. Only a few Larix species constitute the vast forests and these species differ markedly in their ecological traits, most importantly in their ability to grow on and stabilize underlying permafrost. The pronounced dominance of the summergreen larches makes the Asian boreal forests unique, as the rest of the northern hemisphere boreal forests is almost exclusively dominated by evergreen needle-leaf forests. Global warming is impacting the whole world but is especially pronounced in the arctic and boreal regions. Although adapted to extreme climatic conditions, larch forests are sensitive to varying climatic conditions. By their sheer size, changes in Asian larch forests as range shifts or changes in species composition and the resulting vegetation-climate feedbacks are of global relevance. It is however still uncertain if larch forests will persist under the ongoing warming climate or if they will be replaced by evergreen forests. It is therefore of great importance to understand how these ecosystems will react to future climate warmings and if they will maintain their dominance. One step in the better understanding of larch dynamics is to study how the vast dominant forests developed and why they only established in northern Asia. A second step is to study how the species reacted to past changes in the climate. The first objective of this thesis was to review and identify factors promoting Asian larch dominance. I achieved this by synthesizing and comparing reported larch occurrences and influencing components on the northern hemisphere continents in the present and in the past. The second objective was to find a possibility to directly study past Larix populations in Siberia and specifically their genetic variation, enabling the study of geographic movements. For this, I established chloroplast enrichment by hybridization capture from sedimentary ancient DNA (sedaDNA) isolated from lake sediment records. The third objective was to use the established method to track past larch populations, their glacial refugia during the Last Glacial Maximum (LGM) around 21,000 years before present (ka BP), and their post-glacial migration patterns. To study larch promoting factors, I compared the present state of larch species ranges, areas of dominance, their bioclimatic niches, and the distribution on different extents and thaw depths of permafrost. The species comparison showed that the bioclimatic niches greatly overlap between the American and Asian species and that it is only in the extremely continental climates in which only the Asian larch species can persist. I revealed that the area of dominance is strongly connected to permafrost extent but less linked to permafrost seasonal thaw depths. Comparisons of the paleorecord of larch between the continents suggest differences in the recolonization history. Outside of northern Asia and Alaska, glacial refugial populations of larch were confined to the southern regions and thus recolonization could only occur as migration from south to north. Alaskan larch populations could not establish wide-range dominant forest which could be related to their own genetically depletion as separated refugial population. In Asia, it is still unclear whether or not the northern refugial populations contributed and enhanced the postglacial colonization or whether they were replaced by populations invading from the south in the course of climate warming. Asian larch dominance is thus promoted partly by adaptions to extremely continental climates and by adaptations to grow on continuous permafrost but could be also connected to differences in glacial survival and recolonization history of Larix species. Except for extremely rare macrofossil findings of fossilized cones, traditional methods to study past vegetation are not able to distinguish between larch species or populations. Within the scope of this thesis, I therefore established a method to retrieve genetic information of past larch populations to distinguish between species. Using the Larix chloroplast genome as target, I successfully applied the method of DNA target enrichment by hybridization capture on sedaDNA samples from lake records and showed that it is able to distinguish between larch species. I then used the method on samples from lake records from across Siberia dating back up to 50 ka BP. The results allowed me to address the question of glacial survival and post-glacial recolonization mode in Siberian larch species. The analyzed pattern showed that LGM refugia were almost exclusively constituted by L. gmelinii, even in sites of current L. sibirica distribution. For included study sites, L. sibirica migrated into its extant northern distribution area only in the Holocene. Consequently, the post-glacial recolonization of L. sibirica was not enhanced by northern glacial refugia. In case of sites in extant distribution area of L. gmelinii, the absence of a genetic turn-over point to a continuous population rather than an invasion of southern refugia. The results suggest that climate has a strong influence on the distribution of Larix species and that species may also respond differently to future climate warming. Because species differ in their ecological characteristics, species distribution is also relevant with respect to further feedbacks between vegetation and climate. With this thesis, I give an overview of present and past larch occurrences and evaluate which factors promote their dominance. Furthermore, I provide the tools to study past Larix species and give first important insights into the glacial history of Larix populations.

Description / Table of Contents: This book addresses the main enigmas of Easter Island’s (Rapa Nui, in the Polynesian language) prehistory from the time of initial settlement to European contact with a multidisciplinary perspective. The main topics include: (i) the time of first settlement and the origin of the first settlers; (ii) the main features of prehistoric Rapanui culture and their changes; (iii) the deforestation of the island and its timing and causes; (iv) the extinction of the indigenous biota, (v) the occurrence of climatic shifts and their potential effects on socioecological trends; (vi) the evidence for a cultural and demographic collapse before European contact; and (vii) the influence of Europeans on prehistoric Rapanui society. The book is subdivided into thematic sections and each chapter is written by renowned specialists in disciplines such as archaeology, anthropology, paleoecology, ethnography, linguistics, ethnobotany, phylogenetics/phylogeography and history. Contributors have been invited to provide an open and objective vision that includes as many views as possible on the topics considered. In this way, the readers may be able to compare different of points of view and make their own interpretations on each of the subjects considered. The book is intended for a wide audience including graduate students, advanced undergraduate students, university teachers and researchers interested in the subject. Given its multidisciplinary character and the topics included, the book is suitable for students and researchers from a wide range of disciplines and interests.

Description / Table of Contents: Throughout the last ~3 million years, the Earth's climate system was characterised by cycles of glacial and interglacial periods. The current warm period, the Holocene, is comparably stable and stands out from this long-term cyclicality. However, since the industrial revolution, the climate has been increasingly affected by a human-induced increase in greenhouse gas concentrations. While instrumental observations are used to describe changes over the past ~200 years, indirect observations via proxy data are the main source of information beyond this instrumental era. These data are indicators of past climatic conditions, stored in palaeoclimate archives around the Earth. The proxy signal is affected by processes independent of the prevailing climatic conditions. In particular, for sedimentary archives such as marine sediments and polar ice sheets, material may be redistributed during or after the initial deposition and subsequent formation of the archive. This leads to noise in the records challenging reliable reconstructions on local or short time scales. This dissertation characterises the initial deposition of the climatic signal and quantifies the resulting archive-internal heterogeneity and its influence on the observed proxy signal to improve the representativity and interpretation of climate reconstructions from marine sediments and ice cores. To this end, the horizontal and vertical variation in radiocarbon content of a box-core from the South China Sea is investigated. The three-dimensional resolution is used to quantify the true uncertainty in radiocarbon age estimates from planktonic foraminifera with an extensive sampling scheme, including different sample volumes and replicated measurements of batches of small and large numbers of specimen. An assessment on the variability stemming from sediment mixing by benthic organisms reveals strong internal heterogeneity. Hence, sediment mixing leads to substantial time uncertainty of proxy-based reconstructions with error terms two to five times larger than previously assumed. A second three-dimensional analysis of the upper snowpack provides insights into the heterogeneous signal deposition and imprint in snow and firn. A new study design which combines a structure-from-motion photogrammetry approach with two-dimensional isotopic data is performed at a study site in the accumulation zone of the Greenland Ice Sheet. The photogrammetry method reveals an intermittent character of snowfall, a layer-wise snow deposition with substantial contributions by wind-driven erosion and redistribution to the final spatially variable accumulation and illustrated the evolution of stratigraphic noise at the surface. The isotopic data show the preservation of stratigraphic noise within the upper firn column, leading to a spatially variable climate signal imprint and heterogeneous layer thicknesses. Additional post-depositional modifications due to snow-air exchange are also investigated, but without a conclusive quantification of the contribution to the final isotopic signature. Finally, this characterisation and quantification of the complex signal formation in marine sediments and polar ice contributes to a better understanding of the signal content in proxy data which is needed to assess the natural climate variability during the Holocene.

Description / Table of Contents: Это четвертая книга авторского колпектива по силуру Сибирской платформы. в первой части работы даются общая характеристика методологии экостратиграфических исследований, проводимых на Сибирской платформе комnлекснои литолого-палеонтолоrической группой, и сопоставление региональнои шкалы с общей стратиграфической. Затем приводится описание новых свит силура и нижнего девона Норильского и Игарскоrо районов. Во второй части работы дается стратиграфический анализ и описание фауны и флоры. Книга представляет интерес для геологов, стратиграфов и палеонтологов.

Description / Table of Contents: Translation of the abstract: This is the fourth book of the author’s team on the Silurian of the Siberian Platform. The first part of the work provides a general description of the methodology of ecostratigraphic studies carried out on the Siberian platform by an integrated lithological and paleontological group, and a comparison of the regional scale with the general stratigraphic scale. Then a description of the new formations of the Silurian and Lower Devonian of the Norilsk and Igarsk regions is given. The second part of the work provides a stratigraphic analysis and description of the fauna and flora. The book is of interest to geologists, stratigraphers and paleontologists.

Description / Table of Contents: Included in this book are papers on a wide range of problems of geology of the Cenozoic of Yacutia - stratigraphy, paleogeography, structural geomorphology, neotectonics, glaciations, as well as on main stages of man population of Yakutia. The collection of papers is published for the Xlth INQUA Congress. The book is of interest to those dealing with the Cenozoic history of Yakutia and the North-East USSR.

Description / Table of Contents: В сборнике помещены статьи по широкому кругу вопросов геологии кайнозоя Якутии - стратиграфии, палеогеографии, структурной геоморфологии, неотектонике, оледенениям, а также основным этапам заселения человеком территории Якутии. Сборник издается к XI Конгрессу Международного союза по изучению четвертичного периода. Книга представляет интерес для специалистов, занимающихся кайнозойской историей Якутии и Северо-Востока СССР.