ALBERT

Description / Table of Contents: A volcanic eruption occurs when a magma-filled fracture propagates from its source to the surface. Analysing and understanding the conditions that allow this to happen constitute a major part of the scientific field of volcanotectonics. This new volume introduces this cutting-edge and interdisciplinary topic in volcanological research, which incorporates principles and methods from structural geology, tectonics, volcano-deformation studies, physical volcanology, seismology, and physics. It explains and illustrates the physical processes that operate inside volcanoes and which control the frequencies, locations, durations, and sizes of volcanic eruptions. Featuring a clear theoretical framework and helpful summary descriptions of various volcanic structures and products, as well as many worked examples and exercises, this book is an ideal resource for students, researchers and practitioners seeking an understanding of the processes that give rise to volcanic deformation, earthquakes, and eruptions.

Description / Table of Contents: In the Anthropocene, the thawing of frozen earth due to global warming has drawn worldwide attention to permafrost. Contemporary scientists define permafrost as ground that maintains a negative temperature for at least two years. But where did this particular conception of permafrost originate, and what alternatives existed? The Life of Permafrost provides an intellectual history of permafrost, placing the phenomenon squarely in the political, social, and material context of Russian and Soviet science. Pey-Yi Chu shows that understandings of frozen earth were shaped by two key experiences in the Russian Empire and the Soviet Union. On one hand, the colonization and industrialization of Siberia nourished an engineering perspective on frozen earth that viewed the phenomenon as an aggregate physical structure: ground. On the other, a Russian and Soviet tradition of systems thinking encouraged approaching frozen earth as a process, condition, and space tied to planetary exchanges of energy and matter. Aided by the US militarization of the Arctic during the Cold War, the engineering view of frozen earth as an obstacle to construction became dominant. The Life of Permafrost tells the fascinating story of how permafrost came to acquire life as Russian and Soviet scientists studied, named, and defined it.

Description / Table of Contents: Never before have researchers had the chance to explore the Arctic sea ice as comprehensively as on the international MOSAiC expedition. For an entire year, the research icebreaker Polarstern drifted through the Central Arctic with the sea ice; for an entire year, the men and women of the expedition painstakingly investigated the ice with the aid of cutting-edge technologies. In the ten DriftStories gathered here, they share the challenges they had to overcome, and the discoveries they made in this polar hotspot of climate change: fascinating Arctic research at your fingertips - presented by meereisportal.de.

Description / Table of Contents: Die Hochgebirge haben eine große Bedeutung für das globale Klima, die Wasserversorgung und die Biosphäre. So ist die besonders starke Ausprägung des Amazonas-Regenwalds den Anden zu verdanken. Sie verhindern den Durchzug der aus dem Atlantik mit viel Luftfeuchtigkeit kommenden Wolken. Dadurch erhält das Amazonas-Gebiet im Jahresdurchschnitt über 2.000 mm Regen, was die Grundlage für die intensive Bewaldung ist. Obwohl die Gebirge global nur ca. 12% der Landfläche bedecken, beherbergen Hochgebirge rund die Hälfte aller Säugetierarten und 74% aller endemischen Vogelarten (ohne Inselarten). 21 der 34 globalen Biodiversitätshotspots befinden sich in Hochgebirgen. In den Gebirgen entstehen aufgrund von höheren Niederschlägen wichtige Wasserressourcen auch für die angrenzenden Tiefländer. Trotz der für den Menschen oft erschwerten Zugänglichkeit sind Hochgebirge und Hoch-Plateaus, besonders in tropischen Regionen, Orte dichter Besiedlung und sogar von Hochkulturen. Die Folgen des Klimawandels sind in den Hochgebirgen besonders deutlich. So war die Erwärmung in den vergangenen Jahrzehnten dort höher als in den Flachländern. Die Gletscher schrumpfen in fast allen Gebirgen, insbesondere in den letzten Jahrzehnten. Auf den jetzt eisfreien Flächen siedeln sich schon nach wenigen Jahren neue Pflanzengemeinschaften an. In den Alpen hat das Eisvolumen seit 1850 schon um mehr als zwei Drittel abgenommen. Das entspricht allein seit 1997 einem Süßwasserverlust von etwa dem 14fachen Volumen des Bodensees. Insgesamt sind die Klimaänderungen in den Gebirgsregionen gravierender als im Flachland. Mit der Zunahme der Starkregen und dem Rückgang des Permafrosts nimmt die Gefahr von Erdrutschen zu, und manche Gletscher wurden instabil. Im Mittel haben sich die Temperaturen im Gebirgspermafrost in einem Jahrzehnt von 2007 bis 2016 um etwa 0,2°C erhöht. Die Schneedeckendauer nahm in den letzten Jahrzehnten kontinuierlich ab; die Herausforderungen für den Wintertourismus werden zusehends größer.

Description / Table of Contents: Over the last decades, the rate of near-surface warming in the Arctic is at least double than elsewhere on our planet (Arctic amplification). However, the relative contribution of different feedback processes to Arctic amplification is a topic of ongoing research, including the role of aerosol and clouds. Lidar systems are well-suited for the investigation of aerosol and optically-thin clouds as they provide vertically-resolved information on fine temporal scales. Global aerosol models fail to converge on the sign of the Arctic aerosol radiative effect (ARE). In the first part of this work, the optical and microphysical properties of Arctic aerosol were characterized at case study level in order to assess the short-wave (SW) ARE. A long-range transport episode was first investigated. Geometrically similar aerosol layers were captured over three locations. Although the aerosol size distribution was different between Fram Strait(bi-modal) and Ny-Ålesund (fine mono-modal), the atmospheric column ARE was similar. The latter was related to the domination of accumulation mode aerosol. Over both locations top of the atmosphere (TOA) warming was accompanied by surface cooling. Subsequently, the sensitivity of ARE was investigated with respect to different aerosol and spring-time ambient conditions. A 10% change in the single-scattering albedo (SSA) induced higher ARE perturbations compared to a 30% change in the aerosol extinction coefficient. With respect to ambient conditions, the ARETOA was more sensitive to solar elevation changes compared to AREsur f ace. Over dark surfaces the ARE profile was exclusively negative, while over bright surfaces a negative to positive shift occurred above the aerosol layers. Consequently, the sign of ARE can be highly sensitive in spring since this season is characterized by transitional surface albedo conditions. As the inversion of the aerosol microphysics is an ill-posed problem, the inferred aerosol size distribution of a low-tropospheric event was compared to the in-situ measured distribution. Both techniques revealed a bi-modal distribution, with good agreement in the total volume concentration. However, in terms of SSA a disagreement was found, with the lidar inversion indicating highly scattering particles and the in-situ measurements pointing to absorbing particles. The discrepancies could stem from assumptions in the inversion (e.g. wavelength-independent refractive index) and errors in the conversion of the in-situ measured light attenuation into absorption. Another source of discrepancy might be related to an incomplete capture of fine particles in the in-situ sensors. The disagreement in the most critical parameter for the Arctic ARE necessitates further exploration in the frame of aerosol closure experiments. Care must be taken in ARE modelling studies, which may use either the in-situ or lidar-derived SSA as input. Reliable characterization of cirrus geometrical and optical properties is necessary for improving their radiative estimates. In this respect, the detection of sub-visible cirrus is of special importance. The total cloud radiative effect (CRE) can be negatively biased, should only the optically-thin and opaque cirrus contributions are considered. To this end, a cirrus retrieval scheme was developed aiming at increased sensitivity to thin clouds. The cirrus detection was based on the wavelet covariance transform (WCT) method, extended by dynamic thresholds. The dynamic WCT exhibited high sensitivity to faint and thin cirrus layers (less than 200 m) that were partly or completely undetected by the existing static method. The optical characterization scheme extended the Klett–Fernald retrieval by an iterative lidar ratio (LR) determination (constrained Klett). The iterative process was constrained by a reference value, which indicated the aerosol concentration beneath the cirrus cloud. Contrary to existing approaches, the aerosol-free assumption was not adopted, but the aerosol conditions were approximated by an initial guess. The inherent uncertainties of the constrained Klett were higher for optically-thinner cirrus, but an overall good agreement was found with two established retrievals. Additionally, existing approaches, which rely on aerosol-free assumptions, presented increased accuracy when the proposed reference value was adopted. The constrained Klett retrieved reliably the optical properties in all cirrus regimes, including upper sub-visible cirrus with COD down to 0.02. Cirrus is the only cloud type capable of inducing TOA cooling or heating at daytime. Over the Arctic, however, the properties and CRE of cirrus are under-explored. In the final part of this work, long-term cirrus geometrical and optical properties were investigated for the first time over an Arctic site (Ny-Ålesund). To this end, the newly developed retrieval scheme was employed. Cirrus layers over Ny-Ålesund seemed to be more absorbing in the visible spectral region compared to lower latitudes and comprise relatively more spherical ice particles. Such meridional differences could be related to discrepancies in absolute humidity and ice nucleation mechanisms. The COD tended to decline for less spherical and smaller ice particles probably due to reduced water vapor deposition on the particle surface. The cirrus optical properties presented weak dependence on ambient temperature and wind conditions. Over the 10 years of the analysis, no clear temporal trend was found and the seasonal cycle was not pronounced. However, winter cirrus appeared under colder conditions and stronger winds. Moreover, they were optically-thicker, less absorbing and consisted of relatively more spherical ice particles. A positive CREnet was primarily revealed for a broad range of representative cloud properties and ambient conditions. Only for high COD (above 10) and over tundra a negative CREnet was estimated, which did not hold true over snow/ice surfaces. Consequently, the COD in combination with the surface albedo seem to play the most critical role in determining the CRE sign over the high European Arctic.

Description / Table of Contents: В монографии приводятся сведения о составе локальной флоры окрестностей Международной биологической станции 〈〈Лена-Норденшельд», расположенной на территории Усть-Ленского заповедника, относящейся к числу естественных, мало измененных под влиянием человека объектов (98,5 % ее состава представлено аборигенной фракцией, 3 вида - адвентивный компонент, 5 видов - интродуценты), что обеспечивается природоохранными мероприятиями и представляется очень важным для понимания естественных процессов трансформации природы. В ходе обследования данной местности выявлено 266 таксонов сосудистых растений видового и внутривидового ранга. Приводится иллюстрированный фотографиями растений список видов с указанием частоты встречаемости, распределения по высотным поясам растительности и фитоценотической приуроченности. Исследованная локальная флора дополняет и входит в систему региональных флор Хараулахской подпровинции Восточно-Сибирской провинции Арктической флористической области, которая нуждается в дальнейшем изучении. Книга рассчитана на специалистов природоохранной сферы деятельности, учителей биологии, натуралистов-любителей.

Description / Table of Contents: Data about composition of the local flora of the International Biological Station "Lena- Nordenskjöld" vicinities is presented. The station is situated in the Lena River delta, within the territory of the Ust-Lensky Nature Reserve. 266 taxons (255 species, and 9 subspecies, 1 variety, 1 hybrid species) of vascular plants from 109 genera and 42 families were found. The checklist is illustrated with photographs of the plants species and contains information about species frequency and their distribution along altitudinal belts and in various plant communities. The local flora of the International Biological Station is natural and slightly disturbed Ьу men: 98,5 % of its composition are native species, and only 3 species are adventive. Аll the species found there can bе classified in 6 altitudinal groups. 224 species belong to the valley vegetation complex, 161 species grow in the tundra belt, 28 species refer to the epilithic lichen communities belt. The flora belongs to the Кharaulakh subprovince ofthe East-Siberian province ofthe Arctic floristic region, which boundaries need to bе detected. The book is intended for specialists of environmental activities, biology teachers, naturalists and enthusiasts.

Description / Table of Contents: Vegetation change at high latitudes is one of the central issues nowadays with respect to ongoing climate changes and triggered potential feedback. At high latitude ecosystems, the expected changes include boreal treeline advance, compositional, phenological, physiological (plants), biomass (phytomass) and productivity changes. However, the rate and the extent of the changes under climate change are yet poorly understood and projections are necessary for effective adaptive strategies and forehanded minimisation of the possible negative feedbacks. The vegetation itself and environmental conditions, which are playing a great role in its development and distribution are diverse throughout the Subarctic to the Arctic. Among the least investigated areas is central Chukotka in North-Eastern Siberia, Russia. Chukotka has mountainous terrain and a wide variety of vegetation types on the gradient from treeless tundra to northern taiga forests. The treeline there in contrast to subarctic North America and north-western and central Siberia is represented by a deciduous conifer, Larix cajanderi Mayr. The vegetation varies from prostrate lichen Dryas octopetala L. tundra to open graminoid (hummock and non-hummock) tundra to tall Pinus pumila (Pall.) Regel shrublands to sparse and dense larch forests. Hence, this thesis presents investigations on recent compositional and above-ground biomass (AGB) changes, as well as potential future changes in AGB in central Chukotka. The aim is to assess how tundra-taiga vegetation develops under changing climate conditions particularly in Fareast Russia, central Chukotka. Therefore, three main research questions were considered: 1) What changes in vegetation composition have recently occurred in central Chukotka? 2) How have the above-ground biomass AGB rates and distribution changed in central Chukotka? 3) What are the spatial dynamics and rates of tree AGB change in the upcoming millennia in the northern tundra-taiga of central Chukotka? Remote sensing provides information on the spatial and temporal variability of vegetation. I used Landsat satellite data together with field data (foliage projective cover and AGB) from two expeditions in 2016 and 2018 to Chukotka to upscale vegetation types and AGB for the study area. More specifically, I used Landsat spectral indices (Normalised Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI) and Normalised Difference Snow Index (NDSI)) and constrained ordination (Redundancy analysis, RDA) for further k-means-based land-cover classification and general additive model (GAM)-based AGB maps for 2000/2001/2002 and 2016/2017. I also used Tandem-X DEM data for a topographical correction of the Landsat satellite data and to derive slope, aspect, and Topographical Wetness Index (TWI) data for forecasting AGB. Firstly, in 2016, taxa-specific projective cover data were collected during a Russian-German expedition. I processed the field data and coupled them with Landsat spectral Indices in the RDA model that was used for k-means classification. I could establish four meaningful land-cover classes: (1) larch closed-canopy forest, (2) forest tundra and shrub tundra, (3) graminoid tundra and (4) prostrate herb tundra and barren areas, and accordingly, I produced the land cover maps for 2000/2001/2002 and 2016/20017. Changes in land-cover classes between the beginning of the century (2000/2001/2002) and the present time (2016/2017) were estimated and interpreted as recent compositional changes in central Chukotka. The transition from graminoid tundra to forest tundra and shrub tundra was interpreted as shrubification and amounts to a 20% area increase in the tundra-taiga zone and 40% area increase in the northern taiga. Major contributors of shrubification are alder, dwarf birch and some species of the heather family. Land-cover change from the forest tundra and shrub tundra class to the larch closed-canopy forest class is interpreted as tree infilling and is notable in the northern taiga. We find almost no land-cover changes in the present treeless tundra. Secondly, total AGB state and change were investigated for the same areas. In addition to the total vegetation AGB, I provided estimations for the different taxa present at the field sites. As an outcome, AGB in the study region of central Chukotka ranged from 0 kg m-2 at barren areas to 16 kg m-2 in closed-canopy forests with the larch trees contributing the highest. A comparison of changes in AGB within the investigated period from 2000 to 2016 shows that the greatest changes (up to 1.25 kg m 2 yr 1) occurred in the northern taiga and in areas where land cover changed to larch closed-canopy forest. Our estimations indicate a general increase in total AGB throughout the investigated tundra-taiga and northern taiga, whereas the tundra showed no evidence of change in AGB within the 15 years from 2002 to 2017. In the third manuscript, potential future AGB changes were estimated based on the results of simulations of the individual-based spatially explicit vegetation model LAVESI using different climate scenarios, depending on Representative Concentration Pathways (RCPs) RCP 2.6, RCP 4.5 and RCP 8.5 with or without cooling after 2300 CE. LAVESI-based AGB was simulated for the current state until 3000 CE for the northern tundra-taiga study area for larch species because we expect the most notable changes to occur will be associated with forest expansion in the treeline ecotone. The spatial distribution and current state of tree AGB was validated against AGB field data, AGB extracted from Landsat satellite data and a high spatial resolution image with distinctive trees visible. The simulation results are indicating differences in tree AGB dynamics plot wise, depending on the distance to the current treeline. The simulated tree AGB dynamics are in concordance with fundamental ecological (emigrational and successional) processes: tree stand formation in simulated results starts with seed dispersion, tree stand establishment, tree stand densification and episodic thinning. Our results suggest mostly densification of existing tree stands in the study region within the current century in the study region and a lagged forest expansion (up to 39% of total area in the RCP 8.5) under all considered climate scenarios without cooling in different local areas depending on the closeness to the current treeline. In scenarios with cooling air temperature after 2300 CE, forests stopped expanding at 2300 CE (up to 10%, RCP 8.5) and then gradually retreated to their pre-21st century position. The average tree AGB rates of increase are the strongest in the first 300 years of the 21st century. The rates depend on the RCP scenario, where the highest are as expected under RCP 8.5. Overall, this interdisciplinary thesis shows a successful integration of field data, satellite data and modelling for tracking recent and predicting future vegetation changes in mountainous subarctic regions. The obtained results are unique for the focus area in central Chukotka and overall, for mountainous high latitude ecosystems.

Description / Table of Contents: The Arctic is changing rapidly and permafrost is thawing. Especially ice-rich permafrost, such as the late Pleistocene Yedoma, is vulnerable to rapid and deep thaw processes such as surface subsidence after the melting of ground ice. Due to permafrost thaw, the permafrost carbon pool is becoming increasingly accessible to microbes, leading to increased greenhouse gas emissions, which enhances the climate warming. The assessment of the molecular structure and biodegradability of permafrost organic matter (OM) is highly needed. My research revolves around the question “how does permafrost thaw affect its OM storage?” More specifically, I assessed (1) how molecular biomarkers can be applied to characterize permafrost OM, (2) greenhouse gas production rates from thawing permafrost, and (3) the quality of OM of frozen and (previously) thawed sediments. I studied deep (max. 55 m) Yedoma and thawed Yedoma permafrost sediments from Yakutia (Sakha Republic). I analyzed sediment cores taken below thermokarst lakes on the Bykovsky Peninsula (southeast of the Lena Delta) and in the Yukechi Alas (Central Yakutia), and headwall samples from the permafrost cliff Sobo-Sise (Lena Delta) and the retrogressive thaw slump Batagay (Yana Uplands). I measured biomarker concentrations of all sediment samples. Furthermore, I carried out incubation experiments to quantify greenhouse gas production in thawing permafrost. I showed that the biomarker proxies are useful to assess the source of the OM and to distinguish between OM derived from terrestrial higher plants, aquatic plants and microbial activity. In addition, I showed that some proxies help to assess the degree of degradation of permafrost OM, especially when combined with sedimentological data in a multi-proxy approach. The OM of Yedoma is generally better preserved than that of thawed Yedoma sediments. The greenhouse gas production was highest in the permafrost sediments that thawed for the first time, meaning that the frozen Yedoma sediments contained most labile OM. Furthermore, I showed that the methanogenic communities had established in the recently thawed sediments, but not yet in the still-frozen sediments. My research provided the first molecular biomarker distributions and organic carbon turnover data as well as insights in the state and processes in deep frozen and thawed Yedoma sediments. These findings show the relevance of studying OM in deep permafrost sediments.

Description / Table of Contents: Climate change of anthropogenic origin is affecting Earth’s biodiversity and therefore ecosystems and their services. High latitude ecosystems are even more impacted than the rest of Northern Hemisphere because of the amplified polar warming. Still, it is challenging to predict the dynamics of high latitude ecosystems because of complex interaction between abiotic and biotic components. As the past is the key to the future, the interpretation of past ecological changes to better understand ongoing processes is possible. In the Quaternary, the Pleistocene experienced several glacial and interglacial stages that affected past ecosystems. During the last Glacial, the Pleistocene steppe-tundra was covering most of unglaciated northern hemisphere and disappeared in parallel to the megafauna’s extinction at the transition to the Holocene (~11,700 years ago). The origin of the steppe-tundra decline is not well understood and knowledge on the mechanisms, which caused shifts in past communities and ecosystems, is of high priority as they are likely comparable to those affecting modern ecosystems. Lake or permafrost core sediments can be retrieved to investigate past biodiversity at transitions between glacial and interglacial stages. Siberia and Beringia were the origin of dispersal of the steppe-tundra, which make investigation this area of high priority. Until recently, macrofossils and pollen were the most common approaches. They are designed to reconstruct past composition changes but have limit and biases. Since the end of the 20th century, sedimentary ancient DNA (sedaDNA) can also be investigated. My main objectives were, by using sedaDNA approaches to provide scientific evidence of compositional and diversity changes in the Northern Hemisphere ecosystems at the transition between Quaternary glacial and interglacial stages. In this thesis, I provide snapshots of entire ancient ecosystems and describe compositional changes between Quaternary glacial and interglacial stages, and confirm the vegetation composition and the spatial and temporal boundaries of the Pleistocene steppe-tundra. I identify a general loss of plant diversity with extinction events happening in parallel of megafauna’ extinction. I demonstrate how loss of biotic resilience led to the collapse of a previously well-established system and discuss my results in regards to the ongoing climate change. With further work to constrain biases and limits, sedaDNA can be used in parallel or even replace the more established macrofossils and pollen approaches as my results support the robustness and potential of sedaDNA to answer new palaeoecological questions such as plant diversity changes, loss and provide snapshots of entire ancient biota.

Description / Table of Contents: Der vom Menschen verursachte Klimawandel wirkt sich auf die biologische Vielfalt der Erde und damit auf die Ökosysteme und ihre Leistungen aus. Die Ökosysteme in den hohen Breitengraden sind aufgrund der verstärkten Erwärmung an den Polen noch stärker betroffen als der Rest der nördlichen Hemisphäre. Dennoch ist es schwierig, die Dynamik von Ökosystemen in den hohen Breitengraden vorherzusagen, da die Wechselwirkungen zwischen abiotischen und biotischen Komponenten sehr komplex sind. Da die Vergangenheit der Schlüssel zur Zukunft ist, ist die Interpretation vergangener ökologischer Veränderungen möglich, um laufende Prozesse besser zu verstehen. Im Quartär durchlief das Pleistozän mehrere glaziale und interglaziale Phasen, welche die Ökosysteme der Vergangenheit beeinflussten. Während des letzten Glazials bedeckte die pleistozäne Steppentundra den größten Teil der unvergletscherten nördlichen Hemisphäre und verschwand parallel zum Aussterben der Megafauna am Übergang zum Holozän (vor etwa 11 700 Jahren). Der Ursprung des Rückgangs der Steppentundra ist nicht gut erforscht, und die Kenntnis über die Mechanismen, die zu den Veränderungen in den vergangenen Lebensgemeinschaften und Ökosystemen geführt haben, ist von hoher Priorität, da sie wahrscheinlich mit denen vergleichbar sind, die sich auf moderne Ökosysteme auswirken. Durch die Entnahme von See- oder Permafrostkernsedimenten kann die vergangene Artenvielfalt an den Übergängen zwischen Eis- und Zwischeneiszeiten untersucht werden. Sibirien und Beringia waren der Ursprung der Ausbreitung der Steppentundra, weshalb die Untersuchung dieses Gebiets hohe Priorität hat. Bis vor kurzem waren Makrofossilien und Pollen die gängigsten Methoden. Sie dienen der Rekonstruktion vergangener Veränderungen in der Zusammensetzung der Bevölkerung, haben aber ihre Grenzen und Schwächen. Seit Ende des 20. Jahrhunderts kann auch sedimentäre alte DNA (sedaDNA) untersucht werden. Mein Hauptziel war es, durch den Einsatz von sedaDNA-Ansätzen wissenschaftliche Beweise für Veränderungen in der Zusammensetzung und Vielfalt der Ökosysteme der nördlichen Hemisphäre am Übergang zwischen den quartären Eiszeiten und Zwischeneiszeiten zu liefern. In dieser Arbeit liefere ich Momentaufnahmen ganzer alter Ökosysteme und beschreibe die Veränderungen in der Zusammensetzung zwischen Quartärglazialen und Interglazialen und bestätige die Vegetationszusammensetzung sowie die räumlichen und zeitlichen Grenzen der pleistozänen Steppentundra. Ich stelle einen allgemeinen Verlust der Pflanzenvielfalt fest, wobei das Aussterben der Pflanzen parallel zum Aussterben der Megafauna verlief. Ich zeige auf, wie der Verlust der biotischen Widerstandsfähigkeit zum Zusammenbruch eines zuvor gut etablierten Systems führte, und diskutiere meine Ergebnisse im Hinblick auf den laufenden Klimawandel. Mit weiteren Arbeiten zur Eingrenzung von Verzerrungen und Grenzen kann sedaDNA parallel zu den etablierteren Makrofossilien- und Pollenansätzen verwendet werden oder diese sogar ersetzen, da meine Ergebnisse die Robustheit und das Potenzial von sedaDNA zur Beantwortung neuer paläoökologischer Fragen wie Veränderungen der Pflanzenvielfalt und -verluste belegen und Momentaufnahmen ganzer alter Biota liefern.

Description / Table of Contents: Diese Arbeit beschäftigt sich mit der Funktionsweise und Wirkung von zivilgesellschaftlichen Netzwerken, die einen Beitrag zur Kommunal- und Regionalentwicklung in peripheren ländlichen Räumen leisten – „weiche“ Faktoren wie Motivation oder Mentalität eingeschlossen. Zunächst werden in einer multiperspektivischen Herangehensweise adäquate Theoriekonzepte zu Kooperation, Verantwortungsteilung und Netzwerken erarbeitet. Den empirischen Kern dieser Dissertation bildet eine qualitative Datenerhebung mittels Leitfaden-gestützter Experteninterviews eines kirchlich initiierten zivilgesellschaftlichen Netzwerks in Nordostbayern. Das transkribierte Interviewmaterial wird nach der Methode der inhaltlich-strukturierenden qualitativen Inhaltsanalyse nach Kuckartz mit einem deduktiv-induktiv erstellten Kategoriensystem ausgewertet und mithilfe thematischer Summarys verdichtet. Ein Schwerpunkt liegt auf der Untersuchung des Zusammenwirkens und der Motivation der beteiligten Akteure aus verschiedenen gesellschaftlichen Gruppen. Eine quantitative Auswertung von Zufriedenheitsdaten der Region im Vergleich zu Daten aus Bayern und Deutschland ergänzt die qualitative empirische Analyse. Als Ergebnis wird – neben Ideen für das Zusammenwirken von staatlichen und zivilgesellschaftlichen Akteuren der Regionalentwicklung – ein Modell für Wirkfaktoren zivilgesellschaftlicher Netzwerke entworfen.

Description / Table of Contents: This atlas is an attempt to translate and consolidate the available knowledge on permafrost. It is a timely book suffused with the compelling enthusiasm of its authors and contributors. Close to a hundred individuals participated in its making, and it does a magnificent job at describing permafrost with maps, words, art, and stories. Far from being an academic product in the traditional sense, it gathers the knowledge from the voices of scientists, Indigenous Peoples, northern residents, and local practitioners to provide a holistic and inclusive view of today’s challenges in the “country of permafrost”.

Description / Table of Contents: The Earth’s gravity field and its temporal variation reveal important information for many disciplines, especially for geosciences. Satellite gravity missions like GOCE, GRACE and GRACE-FO successfully recovered global gravity field models. But the temporal and spa- tial resolution of the gravity field solutions have to be improved in order to meet the user requirements. New concepts for future satellite missions to recover the global gravity field are investigated by means of comprehensive simulations. In terms of sensor behavior, ac- celerometers are one major limiting factor. Thus, this dissertation focuses on them. Cold Atom Interferometry (CAI) accelerometers are promising candidates for future missions due to their long-term stability.

Description / Table of Contents: This book, entitled Tracking Environmental Change Using Lake Sediments: Volume 6 – Sedimentary DNA, provides an overview of the applications of sedimentary DNA-based approaches to paleolimnological studies. These approaches have shown considerable potential in providing information about the long-term changes of overall biodiversity in lakes and their watersheds in response to natural and anthropogenic changes, as well as tracking human migrations over the last thousands of years. Although the first studies investigating the preservation of these molecular proxies in sediments originate from the late-1990s, the number of scientific publications on this topic has increased greatly over the last five years. Alongside numerous ecological findings, several sedimentary DNA studies have been dedicated to understanding the reliability of this approach to reconstruct past ecosystem changes. Despite the major surge of interest, a comprehensive compilation of sedimentary DNA approaches and applications has yet to be attempted. The overall aim of this DPER volume is to fill this knowledge gap.

Description / Table of Contents: This volume provides detailed protocols for the isolation, enumeration, characterization of diverse bacteriophages, including both small to jumbo bacteriophages, from soil, fecal, municipal wastewater, and from food niche samples. Chapters highlight the diversity of bacteriophages in different environments, quantifications using culture, molecular techniques, protocols for isolate, interaction of bacteriophage proteins with host cells, and how to use bacteriophages to transfer foreign genetic elements to bacterial strains. In addition to the above, chapters feature the application of bacteriophages/bacteriophage-derived products. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips (in the Notes section) on troubleshooting and avoiding known pitfalls. Authoritative and cutting-edge, Bacteriophages: Methods and Protocols aims to ensure successful results in further study of this vital field.

Description / Table of Contents: This book provides a cross-disciplinary overview of permafrost and the carbon cycle by providing an introduction into the geographical distribution of permafrost, with a focus on the distribution of permafrost and its soil carbon reservoirs. The chapters explain the basic physical properties and processes of permafrost soils: ice, mineral and organic components, and how these interact with climate, vegetation and geomorphological processes. In particular, the book covers the role of the large quantities of ice in many permafrost soils which are crucial to understanding carbon cycle processes. An explanation is given on how permafrost becomes loaded with ice and carbon. Gas hydrates are also introduced. Structures and processes formed by the intense freeze-thaw action in the active layer are considered (e.g. ice wedging, cryoturbation), and the processes that occur as the permafrost thaws, (pond and lake formation, erosion). The book introduces soil carbon accumulation and decomposition mechanisms and how these are modified in a permafrost environment. A separate chapter deals with deep permafrost carbon, gas reservoirs and recently discovered methane emission phenomena from regions such as Northwest Siberia and the Siberian yedoma permafrost.

Description / Table of Contents: Der zentralasiatische Naturraum, wie er sich uns heute präsentiert, ist das Ergebnis eines Zusammenwirkens vieler verschiedener Faktoren über Jahrmillionen hinweg. Im aktuellen Kontext des Klimawandels zeigt sich jedoch, wie stark sich Stoffflüsse auch kurzfristig ändern und dabei das Gesicht der Landschaft verwandeln können. Die Gobi-Wüste in der Inneren Mongolei (China), als Teil der gleichnamigen Trockenregionen Nordwestchinas, ist aufgrund der Ausgestaltung ihrer landschaftsprägenden Elemente sowie ihrer Landschaftsdynamik, im Zusammenhang mit der Lage zum Tibet-Plateau, in den Fokus der klimageschichtlichen Grundlagenforschung gerückt. Als großes Langzeitarchiv unterschiedlichster fluvialer, lakustriner und äolischer Sedimente stellt sie eine bedeutende Lokalität zur Rekonstruktion von lokalen und regionalen Stoffflüssen dar.. Andererseits ist die Gobi-Wüste zugleich auch eine bedeutende Quelle für den überregionalen Staubtransport, da sie aufgrund der klimatischen Bedingungen insbesondere der Erosion durch Ausblasung preisgegeben wird. Vor diesem Hintergrund erfolgten zwischen 2011 und 2014, im Rahmen des BMBF-Verbundprogramms WTZ Zentralasien – Monsundynamik & Geoökosysteme (Förderkennzeichen 03G0814), mehrere deutsch-chinesische Expeditionen in das Ejina-Becken (Innere Mongolei) und das Qilian Shan-Vorland. Im Zuge dieser Expeditionen wurden für eine Bestimmung potenzieller Sedimentquellen erstmals zahlreiche Oberflächenproben aus dem gesamten Einzugsgebiet des Heihe (schwarzer Fluss) gesammelt. Zudem wurden mit zwei Bohrungen im inneren des Ejina-Beckens, ergänzende Sedimentbohrkerne zum bestehenden Bohrkern D100 (siehe Wünnemann (2005)) abgeteuft, um weit reichende, ergänzende Informationen zur Landschaftsgeschichte und zum überregionalen Sedimenttransfer zu erhalten. Gegenstand und Ziel der vorliegenden Doktorarbeit ist die sedimentologisch-mineralogische Charakterisierung des Untersuchungsgebietes in Bezug auf potenzielle Sedimentquellen und Stoffflüsse des Ejina-Beckens sowie die Rekonstruktion der Ablagerungsgeschichte eines dort erbohrten, 19m langen Sedimentbohrkerns (GN100). Schwerpunkt ist hierbei die Klärung der Sedimentherkunft innerhalb des Bohrkerns sowie die Ausweisung von Herkunftssignalen und möglichen Sedimentquellen bzw. Sedimenttransportpfaden. Die methodische Herangehensweise basiert auf einem Multi-Proxy-Ansatz zur Charakterisierung der klastischen Sedimentfazies anhand von Geländebeobachtungen, lithologisch-granulometrischen und mineralogisch-geochemischen Analysen sowie statistischen Verfahren. Für die mineralogischen Untersuchungen der Sedimente wurde eine neue, rasterelektronenmikroskopische Methode zur automatisierten Partikelanalyse genutzt und den traditionellen Methoden gegenübergestellt. Die synoptische Betrachtung der granulometrischen, geochemischen und mineralogischen Befunde der Oberflächensedimente ergibt für das Untersuchungsgebiet ein logisches Kaskadenmodell mit immer wiederkehrenden Prozessbereichen und ähnlichen Prozesssignalen. Die umfangreichen granulometrischen Analysen deuten dabei auf abnehmende Korngrößen mit zunehmender Entfernung vom Qilian Shan hin und ermöglichen die Identifizierung von vier texturellen Signalen: den fluvialen Sanden, den Dünensanden, den Stillwassersedimenten und Stäuben. Diese Ergebnisse können als Interpretationsgrundlage für die Korngrößenanalysen des Bohrkerns genutzt werden. Somit ist es möglich, die Ablagerungsgeschichte der Bohrkernsedimente zu rekonstruieren und in Verbindung mit eigenen und literaturbasierten Datierungen in einen Gesamtkontext einzuhängen. Für das Untersuchungsgebiet werden somit vier Ablagerungsphasen ausgewiesen, die bis in die Zeit des letzten glazialen Maximums (LGM) zurückreichen. Während dieser Ablagerungsphasen kam es im Zuge unterschiedlicher Aktivitäts- und Stabilitätsphasen zu einer kontinuierlichen Progradation und Überprägung des Schwemmfächers. Eine besonders aktive Phase kann zwischen 8 ka und 4 ka BP festgestellt werden, während der es aufgrund zunehmender fluvialer Aktivitäten zu einer deutlich verstärkten Schwemmfächerdynamik gekommen zu sein scheint. In den Abschnitten davor und danach waren es vor allem äolische Prozesse, die zu einer Überprägung des Schwemmfächers geführt haben. Hinsichtlich der mineralogischen Herkunftssignale gibt es eine große Variabilität. Dies spiegelt die enorme Heterogenität der Geologie des Untersuchungsgebietes wider, wodurch die räumlichen Signale nicht sehr stark ausgeprägt sind. Dennoch, können für das Einzugsgebiet drei größere Bereiche deklariert werden, die als Herkunftsgebiet in Frage kommen. Das östliche Qilian Shan Vorland zeichnet sich dabei durch deutlich höhere Chloritgehalte als primäre Quelle für die Sedimente im Ejina-Becken aus. Sie unterscheiden sich insbesondere durch stark divergierende Chloritgehalte in der Tonmineral- und Gesamtmineralfraktion, was das östliche Qilian Shan Vorland als primäre Quelle für die Sedimente im Ejina-Becken auszeichnet. Dies steht in Zusammenhang mit den Grünschiefern, Ophioliten und Serpentiniten in diesem Bereich. Geochemisch deutet vor allem das Cr/Rb-Verhältnis eine große Variabilität innerhalb des Einzugsgebietes an. Auch hier ist es das östliche Vorland, welches aufgrund seines hohen Anteils an mafischen Gesteinen reich an Chromiten und Spinellen ist und sich somit vom restlichen Untersuchungsgebiet abhebt. Die zeitliche aber auch die generelle Variabilität der Sedimentherkunft lässt sich in den Bohrkernsedimenten nicht so deutlich nachzeichnen. Die mineralogisch-sedimentologischen Eigenschaften der erbohrten klastischen Sedimente zeugen zwar von zwischenzeitlichen Änderungen bei der Sedimentherkunft, diese sind jedoch nicht so deutlich ausgeprägt, wie es die Quellsignale in den Oberflächensedimenten vermuten lassen. Ein Grund dafür scheint die starke Vermischung unterschiedlichster Sedimente während des Transportes zu sein. Die Kombination der Korngrößenergebnisse mit den Befunden der Gesamt- und Schwermineralogie deuten darauf hin, dass es zwischenzeitlich eine Phase mit überwiegend äolischen Prozessen gegeben hat, die mit einem Sedimenteintrag aus dem westlichen Bei Shan in Verbindung stehen. Neben der Zunahme ultrastabiler Schwerminerale wie Zirkon und Granat und der Abnahme opaker Schwerminerale, weisen vor allem die heutigen Verhältnisse darauf hin. Der Vergleich der traditionellen Schwermineralanalyse mit der Computer-Controlled-Scanning-Electron-Microscopy (kurz: CCSEM), die eine automatisierte Partikelauswertung der Proben ermöglicht, zeigt den deutlichen Vorteil der modernen Analysemethode. Neben einem zeitlichen Vorteil, den man durch die automatisierte Abarbeitung der vorbereiteten Proben erlangen kann, steht vor allem die deutlich größere statistische Signifikanz des Ergebnisses im Vordergrund. Zudem können mit dieser Methode auch chemische Varietäten einiger Schwerminerale bestimmt werden, die eine noch feinere Klassifizierung und sicherere Aussagen zu einer möglichen Sedimentherkunft ermöglichen. Damit ergeben sich außerdem verbesserte Aussagen zu Zusammensetzungen und Entstehungsprozessen der abgelagerten Sedimente. Die Studie verdeutlicht, dass die Sedimentherkunft innerhalb des Untersuchungsgebietes sowie die ablaufenden Prozesse zum Teil stark von lokalen Gegebenheiten abhängen. Die Heterogenität der Geologie und die Größe des Einzugsgebietes sowie die daraus resultierende Komplexität der Sedimentgenese, machen exakte Zuordnungen zu klar definierten Sedimentquellen sehr schwer. Dennoch zeigen die Ergebnisse, dass die Sedimentzufuhr in das Ejina-Becken in erster Linie durch fluviale klastische Sedimente des Heihe aus dem Qilian Shan erfolgt sein muss. Die Untersuchungsergebnisse zeigen jedoch ebenso die Notwendigkeit einer ergänzenden Bearbeitung angrenzender Untersuchungsgebiete, wie beispielsweise den Gobi-Altai im Norden oder den Beishan im Westen, sowie die Verdichtung der Oberflächenbeprobung zur feineren Auflösung von lokalen Sedimentquellen.

Description / Table of Contents: Der exklusive Fotoband zur Jahrhundertexpedition in die Arktis. Im September 2019 legte die Polarstern in Richtung Arktis ab - an Bord das internationale MOSAiC-Forscherteam, das die Auswirkungen des Klimawandels auf das ewige Eis erkundet. Chronologisch aufgebaut dokumentiert der bildgewaltige Band in bisher ungesehenen Fotografien von Esther Horvath Leben und Arbeiten während der einjährigen Reise unter den extremen Bedingungen am Nordpol. Begleitet von kenntnisreichen Essays und Textbeiträgen von Experten, Wissenschaftlern und Expeditionsteilnehmern ist der Band ein eindrucksvolles Zeugnis der wohl größten klimatischen Herausforderung unserer Zeit und bietet Einblicke in dieses einmalige Forschungsprojekt sowie die spektakuläre, schützenswerte Polarlandschaft.

Description / Table of Contents: Die Neue Zürcher Zeitung zählt zu den bedeutendsten Tageszeitungen deutscher Sprache und wird auch international sehr geschätzt. Seit gut zwanzig Jahren durchlebt sie jedoch einen Modernisierungsprozess von großer Radikalität und mit weitreichenden Folgen: Dies ist das Porträt einer nationalen Institution und ihres Wandels. Auch eine Zeitung wie die NZZ muss sich, wie alle Printmedien, im Zeitalter des Internets und der Globalisierung neu erfinden. Eine Notwendigkeit, die umso brutaler und tiefgreifender erfolgt, als das Ausmaß des digitalen Siegeszugs und des Wandels der Lesegewohnheiten lange unterschätzt wurde und zusätzlich erschwert wird durch den bisherigen Erfolg und die hohe Anerkennung, der sich die NZZ - national wie international - erfreut. Dieses Buch schildert die radikalen Veränderungen und Umwälzungen eines Weltblatts ab den 1970er-Jahren bis in die Gegenwart, liefert Einblicke ins Innere der NZZ, unterhält mit Episoden aus dem Redaktions- und Korrespondentdasein.

Description / Table of Contents: Permafrost is warming globally, which leads to widespread permafrost thaw and impacts the surrounding landscapes, ecosystems and infrastructure. Especially ice-rich permafrost is vulnerable to rapid and abrupt thaw, resulting from the melting of excess ground ice. Local remote sensing studies have detected increasing rates of abrupt permafrost disturbances, such as thermokarst lake change and drainage, coastal erosion and RTS in the last two decades. All of which indicate an acceleration of permafrost degradation. In particular retrogressive thaw slumps (RTS) are abrupt disturbances that expand by up to several meters each year and impact local and regional topographic gradients, hydrological pathways, sediment and nutrient mobilisation into aquatic systems, and increased permafrost carbon mobilisation. The feedback between abrupt permafrost thaw and the carbon cycle is a crucial component of the Earth system and a relevant driver in global climate models. However, an assessment of RTS at high temporal resolution to determine the ...

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: This multidisciplinary book discusses the manifold challenges arctic marine and terrestrial wildlife, ecosystems and people face these times. Major health threats caused by the consequences of climate change, environmental pollution and increasing tourism in northern regions around the globe are explored. The most common infectious diseases in wild and domesticated arctic animals are reviewed and the impact they could have on circumpolar ecosystems as well as on the lives of arctic people are profoundly discussed. Moreover, the book reviews arctic hunting, herding and food conservation strategies and introduces veterinary medicine in remote indigenous communities. "Arctic One Health" is authored by experts based in arctic regions spanning from North America over Europe to Asia to cover a broad range of topics and perspectives. The book addresses researchers in Veterinary Medicine, Ecology, Microbiology and Anthropology. The book contributes towards achieving the UN Sustainable Developmental Goals, in particular SDG 15, Life on Land.

Description / Table of Contents: Издание представляет собой новейшую таксономическую обработку флоры Якутии, подготовленную весьма квалифицированным и представительным коллективом авторов (более 50 специалистов, включая 15 докторов и 30 кандидатов наук). Даны ключи для определения 1950 видов, 133 подвидов и 34 разновидностей, а также 46 нотовидов, объединенных в 525 родов, 6 нотородов, 113 семейств сосудистых растений, распространенных или когда-либо отмеченных (в том числе очень редких, заносных или дичающих культурных) на территории региона. При: ведены диагностические признаки растений, сведения об их фитоценотическои или экологической приуроченности и распространении. Книга рассчитана на ботаников широкого профиля, студентов, учителей и преподавателей, ученых, биологов, экологов, работников сельского хозяйства, административных работников, отвечающих за эксплуатацию природных ресурсов.

Description / Table of Contents: English translation of the Russian abstract: The publication is the latest taxonomic processing of the flora of Yakutia, prepared by a highly qualified and representative team of authors (more than 50 specialists, including 15 doctors and 30 candidates of sciences). Keys are given to identify 1950 species, 133 subspecies and 34 varieties, as well as 46 nothospecies, united in 525 genera, 6 nothorodes, 113 families of vascular plants, common or ever recorded (including very rare, adventive or wild cultivated) on the territory of the region. When: diagnostic signs of plants, information about their phytocenotic or ecological confinement and distribution are entered. The book is intended for general botanists, students, teachers and teachers, scientists, biologists, ecologists, agricultural workers, administrative workers responsible for the exploitation of natural resources.

Description / Table of Contents: Extreme weather and climate events are one of the greatest dangers for present-day society. Therefore, it is important to provide reliable statements on what changes in extreme events can be expected along with future global climate change. However, the projected overall response to future climate change is generally a result of a complex interplay between individual physical mechanisms originated within the different climate subsystems. Hence, a profound understanding of these individual contributions is required in order to provide meaningful assessments of future changes in extreme events. One aspect of climate change is the recently observed phenomenon of Arctic Amplification and the related dramatic Arctic sea ice decline, which is expected to continue over the next decades. The question to what extent Arctic sea ice loss is able to affect atmospheric dynamics and extreme events over mid-latitudes has received a lot of attention over recent years and still remains a highly debated topic. In this respect, the objective of ...

Description / Table of Contents: Semantic segmentation is an important task in computer vision to help machines gain a high-level understanding of the environment, similar to the human vision system. For example it is used in self-driving cars which are equipped with various sensors such as cameras and 3D laser scanners to gain a complete understanding of their environment. In recent years the field has been dominated by Deep Neural Networks (DNNs), which are notorious for requiring large amounts of training data. Creating these datasets is very time consuming and costly. Moreover, the datasets can only be applied to a specific type of sensor. The present work addresses this problem. It will be shown that knowledge from publicly available image datasets can be reused to minimize the labeling costs for 3D point clouds. For this purpose, the labels from classified images are transferred to 3D point clouds. To bridge the gap between sensor modalities, the geometric relationship of the sensors in a fully calibrated system is used. Due to various errors the naive label transfer can lead to a significant amount of incorrect class label assignments in 3D. Within the work the different reasons and possible solutions are shown in order to improve the label transfer.

Description / Table of Contents: This dissertation shows the importance of using low-cost crowd-sourced information for the task of traffic regulator recognition (traffic signals, stop signs, priority signs, uncontrolled intersections), the cost of which in terms of time and money is much higher if standard technology is used for surveying. GPS trajectories can reveal the movement patterns of traffic participants, and the initial hypothesis that traffic regulations can be retrieved by mining the movement patterns imposed by traffic rules is verified. The predictive ability of the classifier becomes more accurate when static information derived from open maps (OSM) is merged with dynamic features extracted from GPS trajectories. An extensive evaluation of the proposed methodology on three datasets, provided classification accuracy between 95% and 97%.

Description / Table of Contents: The icosahedral non-hydrostatic large eddy model (ICON-LEM) was applied around the drift track of the Multidisciplinary Observatory Study of the Arctic (MOSAiC) in 2019 and 2020. The model was set up with horizontal grid-scales between 100m and 800m on areas with radii of 17.5km and 140 km. At its lateral boundaries, the model was driven by analysis data from the German Weather Service (DWD), downscaled by ICON in limited area mode (ICON-LAM) with horizontal grid-scale of 3 km. The aim of this thesis was the investigation of the atmospheric boundary layer near the surface in the central Arctic during polar winter with a high-resolution mesoscale model. The default settings in ICON-LEM prevent the model from representing the exchange processes in the Arctic boundary layer in accordance to the MOSAiC observations. The implemented sea-ice scheme in ICON does not include a snow layer on sea-ice, which causes a too slow response of the sea-ice surface temperature to atmospheric changes. To allow the sea-ice surface to respond faster to changes in the atmosphere, the implemented sea-ice parameterization in ICON was extended with an adapted heat capacity term. The adapted sea-ice parameterization resulted in better agreement with the MOSAiC observations. However, the sea-ice surface temperature in the model is generally lower than observed due to biases in the downwelling long-wave radiation and the lack of complex surface structures, like leads. The large eddy resolving turbulence closure yielded a better representation of the lower boundary layer under strongly stable stratification than the non-eddy-resolving turbulence closure. Furthermore, the integration of leads into the sea-ice surface reduced the overestimation of the sensible heat flux for different weather conditions. The results of this work help to better understand boundary layer processes in the central Arctic during the polar night. High-resolving mesoscale simulations are able to represent temporally and spatially small interactions and help to further develop parameterizations also for the application in regional and global models.

Description / Table of Contents: With Arctic ground as a huge and temperature-sensitive carbon reservoir, maintaining low ground temperatures and frozen conditions to prevent further carbon emissions that contrib-ute to global climate warming is a key element in humankind’s fight to maintain habitable con-ditions on earth. Former studies showed that during the late Pleistocene, Arctic ground condi-tions were generally colder and more stable as the result of an ecosystem dominated by large herbivorous mammals and vast extents of graminoid vegetation – the mammoth steppe. Characterised by high plant productivity (grassland) and low ground insulation due to animal-caused compression and removal of snow, this ecosystem enabled deep permafrost aggrad-ation. Now, with tundra and shrub vegetation common in the terrestrial Arctic, these effects are not in place anymore. However, it appears to be possible to recreate this ecosystem local-ly by artificially increasing animal numbers, and hence keep Arctic ground cold to reduce or-ganic matter decomposition and carbon release into the atmosphere. By measuring thaw depth, total organic carbon and total nitrogen content, stable carbon iso-tope ratio, radiocarbon age, n-alkane and alcohol characteristics and assessing dominant vegetation types along grazing intensity transects in two contrasting Arctic areas, it was found that recreating conditions locally, similar to the mammoth steppe, seems to be possible. For permafrost-affected soil, it was shown that intensive grazing in direct comparison to non-grazed areas reduces active layer depth and leads to higher TOC contents in the active layer soil. For soil only frozen on top in winter, an increase of TOC with grazing intensity could not be found, most likely because of confounding factors such as vertical water and carbon movement, which is not possible with an impermeable layer in permafrost. In both areas, high animal activity led to a vegetation transformation towards species-poor graminoid-dominated landscapes with less shrubs. Lipid biomarker analysis revealed that, even though the available organic material is different between the study areas, in both permafrost-affected and sea-sonally frozen soils the organic material in sites affected by high animal activity was less de-composed than under less intensive grazing pressure. In conclusion, high animal activity af-fects decomposition processes in Arctic soils and the ground thermal regime, visible from reduced active layer depth in permafrost areas. Therefore, grazing management might be utilised to locally stabilise permafrost and reduce Arctic carbon emissions in the future, but is likely not scalable to the entire permafrost region.

Description / Table of Contents: This book provides a comprehensive, up-to-date assessment of the key terrestrial components of the Arctic system, i.e., its hydrology, permafrost, and ecology, drawing on the latest research results from across the circumpolar regions. The Arctic is an integrated system, the elements of which are closely linked by the atmosphere, ocean, and land. Using an integrated system approach, the book’s 30 chapters, written by a diverse team of leading scholars, carefully examine Arctic climate variability/change, large river hydrology, lakes and wetlands, snow cover and ice processes, permafrost characteristics, vegetation/landscape changes, and the future trajectory of Arctic system evolution. The discussions cover the fundamental features of and processes in the Arctic system, with a special focus on critical knowledge gaps, i.e., the interactions and feedbacks between water, permafrost, and ecosystem, such as snow pack and permafrost changes and their impacts on basin hydrology and ecology, river flow, geochemistry, and energy fluxes to the Arctic Ocean, and the structure and function of the Arctic ecosystem in response to past/future changes in climate, hydrology, and permafrost conditions. Given its scope, the book offers a valuable resource for researchers, graduate students, environmentalists, managers, and administrators who are concerned with the northern environment and resources.

Description / Table of Contents: Die MOSAiC-Expedition verschiebt die Grenzen des Machbaren und markiert einen historischen Meilenstein der Polarforschung. In den Fußstapfen von Fridtjof Nansens bahnrechender Pionierleistung in den Jahren 1893 bis 1896 mit seinem hölzernen Segelschiff »Fram« bringt sie erstmals einen modernen Forschungseisbrecher im Winter in die direkte Umgebung des Nordpols. 20 Nationen haben sich zusammengetan, um die Geheimnisse des dramatischen Klimawandels der Arktis zu entschlüsseln. Untertützt wird das Flaggschiff der Expedition, der deutsche Forschungseisbrecher »Polarstern«, von sechs weiteren Schiffen und Eisbrechern, Flugzeugen und Helikoptern. Insgesamt fünfhundert Menschen nehmen an den verschiedenen Phasen der Expedition teil. Markus Rex, Kopf des Vorhabens und Expeditionsleiter, berichtet anschaulich vom oft genug dramatischen Verlauf dieser Expedition, aber auch von überwältigend faszinierenden Eindrücken aus der Arktis während der langen winterlichen Polarnacht und während des sommerlichen Polartags. Und er beschreibt die unvorstellbaren Herausforderungen, denen sich die Expeditionsteilnehmer eingefroren im polaren Eis gestellt haben - immer geleitet von dem Ziel, Licht in die Prozesse des globalen Klimawandels zu bringen, der nirgends so auseprägt ist wie in der Arktis.

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: Anthropogenic climate change constitutes one of the main global crises in the 21st century. It manifests itself distinctly in global warming and its effects. Forests play an essential role in mitigating the effects of climate change, improving our knowledge of the distribution and changes of terrestrial carbon stocks is vital to mitigate its consequences. Therefore, remote sensing is recommended as one of the tools to ensure systematic and operational forest monitoring. Forests in the Russian Federation are of particular importance as it is the most forested country in the world and at the same time, it is the country with the highest uncertainty when calculating global carbon stocks. Remote sensing is recommended as one of the tools to ensure systematic and operational forest monitoring. It can acquire data over large areas with a high repetition rate and at a relatively low cost. In particular, microwave sensors are recommended as they can provide weather and sun independent, systematic observations with high temporal frequency. The main goal of this cumulative dissertation was to develop methods using new algorithms for estimating parameters for boreal forests from remote sensing data acquired with Synthetic Aperture Radar (SAR). Using the SAR data acquired by the sensor with the longest wavelength available at the moment of writing this dissertation in space, the L-band, methods for estimating the above-ground forest biomass were developed. For this purpose, algorithms for machine learning (ML) were applied and validated. These methods were chosen because they are recommended for large data sets and an incomplete theoretical understanding of processes, e.g., the interaction between the forest and the radar signal, and are relatively new in forest monitoring studies. In addition, efforts have been made to establish improved mapping of large-scale forest cover change

Description / Table of Contents: The Arctic nearshore zone plays a key role in the carbon cycle. Organic-rich sediments get eroded off permafrost affected coastlines and can be directly transferred to the nearshore zone. Permafrost in the Arctic stores a high amount of organic matter and is vulnerable to thermo-erosion, which is expected to increase due to climate change. This will likely result in higher sediment loads in nearshore waters and has the potential to alter local ecosystems by limiting light transmission into the water column, thus limiting primary production to the top-most part of it, and increasing nutrient export from coastal erosion. Greater organic matter input could result in the release of greenhouse gases to the atmosphere. Climate change also acts upon the fluvial system, leading to greater discharge to the nearshore zone. It leads to decreasing sea-ice cover as well, which will both increase wave energy and lengthen the open-water season. Yet, knowledge on these processes and the resulting impact on the nearshore zone is scarce, because access to and instrument deployment in the nearshore zone is challenging. Remote sensing can alleviate these issues in providing rapid data delivery in otherwise non-accessible areas. However, the waters in the Arctic nearshore zone are optically complex, with multiple influencing factors, such as organic rich suspended sediments, colored dissolved organic matter (cDOM), and phytoplankton. The goal of this dissertation was to use remotely sensed imagery to monitor processes related to turbidity caused by suspended sediments in the Arctic nearshore zone. In-situ measurements of water-leaving reflectance and surface water turbidity were used to calibrate a semi-empirical algorithm which relates turbidity from satellite imagery. Based on this algorithm and ancillary ocean and climate variables, the mechanisms underpinning nearshore turbidity in the Arctic were identified at a resolution not achieved before. The calibration of the Arctic Nearshore Turbidity Algorithm (ANTA) was based on in-situ measurements from the coastal and inner-shelf waters around Herschel Island Qikiqtaruk (HIQ) in the western Canadian Arctic from the summer seasons 2018 and 2019. It performed better than existing algorithms, developed for global applications, in relating turbidity from remotely sensed imagery. These existing algorithms were lacking validation data from permafrost affected waters, and were thus not able to reflect the complexity of Arctic nearshore waters. The ANTA has a higher sensitivity towards the lowest turbidity values, which is an asset for identifying sediment pathways in the nearshore zone. Its transferability to areas beyond HIQ was successfully demonstrated using turbidity measurements matching satellite image recordings from Adventfjorden, Svalbard. The ANTA is a powerful tool that provides robust turbidity estimations in a variety of Arctic nearshore environments. Drivers of nearshore turbidity in the Arctic were analyzed by combining ANTA results from the summer season 2019 from HIQ with ocean and climate variables obtained from the weather station at HIQ, the ERA5 reanalysis database, and the Mackenzie River discharge. ERA5 reanalysis data were obtained as domain averages over the Canadian Beaufort Shelf. Nearshore turbidity was linearly correlated to wind speed, significant wave height and wave period. Interestingly, nearshore turbidity was only correlated to wind speed at the shelf, but not to the in-situ measurements from the weather station at HIQ. This shows that nearshore turbidity, albeit being of limited spatial extent, gets influenced by the weather conditions multiple kilometers away, rather than in its direct vicinity. The large influence of wave energy on nearshore turbidity indicates that freshly eroded material off the coast is a major contributor to the nearshore sediment load. This contrasts results from the temperate and tropical oceans, where tides and currents are the major drivers of nearshore turbidity. The Mackenzie River discharge was not identified as a driver of nearshore turbidity in 2019, however, the analysis of 30 years of Landsat archive imagery from 1986 to 2016 suggests a direct link between the prevailing wind direction, which heavily influences the Mackenzie River plume extent, and nearshore turbidity around HIQ. This discrepancy could be caused by the abnormal discharge behavior of the Mackenzie River in 2019. This dissertation has substantially advanced the understanding of suspended sediment processes in the Arctic nearshore zone and provided new monitoring tools for future studies. The presented results will help to understand the role of the Arctic nearshore zone in the carbon cycle under a changing climate.

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: Die Gutachterausschüsse für Grundstückswerte unterliegen dem gesetzlichen Auftrag, regelmäßig flächendeckend Bodenrichtwerte für das Gebiet ihrer Zuständigkeit bereitzustellen. Die praktische Umsetzung dieses Auftrages ist jedoch oft mit erheblichen Problemen verbunden. So liegen regelmäßig – im Verhältnis zur Zahl der fortzuführenden Bodenrichtwertzonen – nur sehr wenige geeignete Vergleichskauffälle unbebauter Grundstücke vor. Zwar stehen auch verschiedene leistungsstarke alternative Verfahren der Bodenrichtwertermittlung zur Verfügung, diese sind für viele Gutachterausschüsse jedoch nicht praktisch umsetzbar. Oft fehlen die hierfür erforderlichen regionalspezifischen Daten, personellen Kapazitäten oder beides. Mit der Zielsetzung, die Gutachterausschüsse in ihrer Aufgabe der Bodenrichtwertermittlung zu unterstützen, wird im Rahmen dieser Arbeit ein Verfahren zur Schätzung von Bodenwerten aus Kaufpreisen bebauter Einfamilienhausgrundstücke entwickelt. Damit kann die Datenbasis zur Bodenrichtwertermittlung für diesen wesentlichen Teilmarkt erheblich erhöht und die Qualität der Bodenrichtwerte deutlich gesteigert werden. Da das Verfahren ohne zusätzliche Datenerhebungen auskommt und zudem in einfacher Weise programmierbar ist, steht dessen Implementierung in den automatisierten Kaufpreissammlungen der Gutachterausschüsse nichts entgegen. Nun werden im Sinn des Baugesetzbuches und der Immobilienwertermittlungsverordnung die Werte bebauten und unbebauten Bodens gleichgesetzt. Im Verständnis des Marktteilnehmers, also im ökonomischen Sinn, ist diese Wertgleichheit jedoch nicht zwangsläufig gegeben. Da es sich um Güter mit unterschiedlichen Eigenschaften handelt, mag der Marktteilnehmer durchaus zu einer differenzierten Einschätzung kommen. Diese Perspektive sollte aber gerade dann, wenn die Wirtschaftlichkeit im Vordergrund steht, berücksichtigt werden. Hierbei ist insbesondere an Fragen der Entschädigung, der Besteuerung oder auch der Bilanzierung zu denken. Es wird daher auch untersucht, welchen Wert der Marktteilnehmer den Grundstücksbestandteilen Boden und Gebäude beimisst. Dies erfolgt, aufbauend auf den Erkenntnissen aus Ökonomie und Psychologie, anhand der mathematischen Modellierung des Prozesses der Kaufpreisbildung. Somit werden in dieser Arbeit Lösungen für zwei verschiedene Aufgaben vorgelegt. Es wird zunächst ein Verfahren entwickelt, welches die Bodenwertableitung aus Kaufpreisen bebauter Einfamilienhausgrundstücke im Sinn der Immobilienwertermittlungsverordnung ermöglicht. Zum anderen wird beantwortet, welchen Anteil am Gesamtwert der genannten Grundstücksarten der Marktteilnehmer dem Boden und den aufstehenden Gebäuden beimisst. Damit wird die seit Jahrzehnten kontrovers diskutierte Repartitionsfrage gelöst.