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  • 2010-2014  (2)
  • 2013  (2)
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  • 2010-2014  (2)
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  • 1
    Call number: AWI Bio-20-93529
    Description / Table of Contents: The Arctic is considered as a focal region in the ongoing climate change debate. The currently observed and predicted climate warming is particularly pronounced in the high northern latitudes. Rising temperatures in the Arctic cause progressive deepening and duration of permafrost thawing during the arctic summer, creating an ‘active layer’ with high bioavailability of nutrients and labile carbon for microbial consumption. The microbial mineralization of permafrost carbon creates large amounts of greenhouse gases, including carbon dioxide and methane, which can be released to the atmosphere, creating a positive feedback to global warming. However, to date, the microbial communities that drive the overall carbon cycle and specifically methane production in the Arctic are poorly constrained. To assess how these microbial communities will respond to the predicted climate changes, such as an increase in atmospheric and soil temperatures causing increased bioavailability of organic carbon, it is necessary to investigate the current status …
    Type of Medium: Dissertations
    Pages: 146 Blätter , Illustrationen
    Language: English
    Note: Table of content Abstract Zusammenfassung 1. Introduction 1.1. Motivation 1.2. Scientific Background 1.2.1. Permafrost in arctic environments 1.2.2. Carbon storage and emission in arctic environments 1.2.3. Methane cycling in arctic environments 1.3. Study Sites 1.3.1. Lena-Delta, Siberia 1.3.2. El’gygytgyn Crater Lake, Chukotka 1.4. Objectives and approach 1.5. Thesis organization 1.6. Summary of the included manuscripts and contribution of the co-authors 1.6.1. Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic 1.6.2. Response of microbial communities to landscape and climatic changes in a terrestrial permafrost sequence of the El’gygytgyn crater, Far East Russian Arctic 1.6.3. Glacial-interglacial microbial community dynamics in Middle Pleistocene sediments in the Lake El’gygytgyn, Far East Russian Arctic 2. Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic 2.1. Abstract 2.2. Introduction 2.3. Materials and Methods 2.3.1. Study site 2.3.2. Permafrost drilling and sample preparation 2.3.3. Sediment properties 2.3.4. Potential methane production rates 2.3.5. Lipid biomarker analysis 2.3.6. Detection of archaeol and isoprenoid GDGTs 2.3.7. Detection of PLFAs and PLELs 2.3.8. DNA extraction and polymerase chain reaction (PCR) amplification 2.3.9. Phylogenetic analysis 2.4. Results and Discussion 2.4.1. Methane profile of the Kurungnakh permafrost sequence 2.4.2. Signals of living microbial communities in the Kurungnakh permafrost sequence 2.4.3. Reconstruction of past microbial communities in the Kurungnakh permafrost sequence 2.4.4. Climate impact on the distribution of microbial communities in the Kurungnakh permafrost sequence 2.4.5. Climatic impact on the composition of methanogenic communities in the Kurungnakh permafrost sequence 2.5. Conclusion 2.6. Acknowledgement 3. Response of microbial communities to landscape and climatic changes in a terrestrial permafrost sequence of the El’gygytgyn crater, Far East Russian Arctic 3.1. Abstract 3.2. Introduction 3.3. Materials and Methods 3.3.1.Study site 3.3.2. Drilling and sample material 3.3.3. Sediment properties 3.3.4. Lipid biomarker analysis 3.3.5. Detection of glycerol dialkyl glycerol tetraethers (GDGTs) and archaeol 3.3.6. Detection of phospholipid fatty acids (PLFA) 3.3.7. Deoxyribonucleic acid (DNA) extraction and amplification 3.3.8. Quantitative PCR analysis of archaeal and bacterial small sub unit (SSU) rRNA genes 3.3.9. Phylogenetic analysis 3.4. Results 3.4.1. TOC-contents 3.4.2. Distribution of glycerol dialkyl glycerol tetraethers (GDGTs) and archaeol 3.4.3. Distribution of phospholipid fatty acids (PLFA) 3.4.4. Composition of archaeol and isoprenoid GDGTs 3.4.5. Quantification of bacterial and archaeal genes 3.4.6. Analysis of methanogenic community fingerprints 3.5. Discussion 3.5.1. Microbial communities in subaquatic deposits 3.5.2. Microbial communities in subaerial deposits 3.5.3. Microbial succession in the Holocene sequence of Lake El’gygytgyn permafrost 3.6.Conclusion 3.7. Acknowledgements 4. Glacial-interglacial microbial community dynamics in Middle Pleistocene sediments in the Lake El’gygytgyn, Far East Russian Arctic 4.1. Abstract 4.2. Introduction 4.3. Materials and Methods 4.3.1. Study site 4.3.2. Drilling and sample preparation 4.3.3. Sediment properties 4.3.4. Lipid biomarker analyses 4.3.5. Deoxyribonucleic acid (DNA) extraction and quantitative polymerase chain reaction (qPCR) 4.3.6. PCR amplification of methanogenic SSU rRNA genes 4.4. Results 4.4.1. Sedimentary TOC and biogenic silica concentration 4.4.2. Quantification of bacterial and archaeal genes 4.4.3. Quantification and composition of lipid biomarkers 4.4.4. Potential methane production 4.4.5. Methanogenic community composition 4.5. Discussion 4.6. Acknowledgements 5. Synthesis 5.1. The reaction of microbial communities to past climatic change in the Arctic 5.2.The response of microbial communities to carbon composition and availability 5.3. Implications from this study for future research 6. Data collection 6.1. Manuscript I: Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic 6.1.1. Sediment properties 6.1.2. Isoprenoid glycerol dialkyl glycerol tetraethers and archaeol 6.1.3. Branched glycerol dialkyl glycerol tetraethers 6.1.4. Phospholipid ester and ether lipids (summary) 6.2. Manuscript II: Response of microbial communities to landscape and climatic changes in a terrestrial permafrost sequence of the El’gygytgyn crater, Far East Russian Arctic 6.2.1. Sediment properties and gene quantifications 6.2.2. Phospholipid fatty acids composition 6.2.3. Isoprenoid glycerol dialkyl glycerol tetraethers and archaeol 6.2.4. Branched glycerol dialkyl glycerol tetraethers 6.3. Manuscript III: Glacial-interglacial microbial community dynamics in Middle Pleistocene sediments in the Lake El’gygytgyn, Far East Russian Arctic 6.3.1. Sediment properties and gene quantifications 6.3.2. Isoprenoid glycerol dialkyl glycerol tetraethers and archaeol 6.3.3. Branched glycerol dialkylglycerol tetraethers 7. References 8. Final thoughts and acknowledgements 9. Curriculum vitae 10.Erklärung
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  • 2
    Call number: AWI Bio-20-93530
    Description / Table of Contents: The Arctic tundra, covering approx. 5.5 % of the Earth’s land surface, is one of the last ecosystems remaining closest to its untouched condition. Remote sensing is able to provide information at regular time intervals and large spatial scales on the structure and function of Arctic ecosystems. But almost all natural surfaces reveal individual anisotropic reflectance behaviors, which can be described by the bidirectional reflectance distribution function (BRDF). This effect can cause significant changes in the measured surface reflectance depending on solar illumination and sensor viewing geometries. The aim of this thesis is the hyperspectral and spectro-directional reflectance characterization of important Arctic tundra vegetation communities at representative Siberian and Alaskan tundra sites as basis for the extraction of vegetation parameters, and the normalization of BRDF effects in off-nadir and multi-temporal remote sensing data. Moreover, in preparation for the upcoming German EnMAP (Environmental Mapping and Analysis Program…
    Type of Medium: Dissertations
    Pages: circa 330 Seiten , Illustrationen, Diagramme
    Language: English
    Note: TABLE OF CONTENTS Abstract Kurzfassung Table of Contents List of Figures List of Tables List of Abbreviations List of Symbols 1 INTRODUCTION 1.1 Background and Scientific Setting 1.2 Motivation and Research Questions 1.3 Structure of Thesis 2 FUNDAMENTALS OF HYPERSPECTRAL AND SPECTRO-DIRECTIONAL REMOTE SENSING 2.1 Hyperspectral Remote Sensing of Vegetation 2.2 Spectro-Directional Remote Sensing of Vegetation 2.3 The EnMAP Satellite System 2.4 Spectro-Goniometer Systems for the Ground-Based Measurement of BRDF Effects 3 THE TUNDRA PERMAFROST STUDY LOCATIONS AND THEIR ENVIRONMENT 3.1 The Eurasia Arctic Transect (EAT) 3.1.1 Geological and Climatic Setting 3.1.2 Vegetation 3.2 The North American Arctic Transect (NAAT) 3.2.1 Geological and Climatic Setting 3.2.2 Vegetation 4 OBSERVATIONS AND METHODOLOGY 4.1 Observations Used for this Study 4.1.1 The ECI-GOA-Yamal 2011 Expedition 4.1.2 The EyeSight- NAAT-Alaska 2012 Expedition 4.1.3 Data Used for Hyperspectral Characterization of Arctic Tundra 4.1.4 Data Used for Spectro-Directional Characterization of Arctic Tundra 4.2 Methodology Used for Field Work and Data Analysis 4.2.1 Field Spectroscopy and Hyperspectral Data Analysis 4.2.2 Considerations for the Field Spectro-Goniometer Measurements and the Spectro-Directional Data Analysis 5 DEVELOPMENT AND PRECOMMISSIONING INSPECTION OF THE MANTIS FIELD SPECTRO-GONIOMETER 5.1 Introduction 5.2 Theoretical Background 5.3 Description of the Field Spectro-Goniometer System 5.3.1 Construction Schedule 5.3.2 Description of the Field Spectro-Goniometer Platform (ManTIS) 5.3.3 Sensor Configuration of the AWI ManTIS Field Spectro-Goniometer 5.3.4 Measurement Strategy 5.3.5 Software for Semi-Automatic Control 5.4 Error Assessment 5.4.1 Radiometrical Accuracy 5.4.2 Pointing Accuracy 5.4.3 Ground Instantaneous Field of View and Sensor Self-Shadowing 5.4.4 Temporal Illumination Changes and Environmental Influences 5.5 Data Analysis 5.5.1 Data Processing 5.5.2 Data Visualization 5.6 Performance of ManTIS Field Spectro-Goniometer in the Field 5.6.1 Test Site and Experiment Setup 5.6.2 Results and Discussion 5.7 Conclusions and Outlook 6 HYPERSPECTRAL REFLECTANCE CHARACTERIZATION OF LOW ARCTIC TUNDRA VEGETATION 6.1 Introduction 6.2 Material & Methods 6.2.1 Study Area 6.2.2 Environmental Gradients/Zones and Vegetation Description 6.2.3 Data Acquisition and Pre-Processing 6.2.4 Data Analysis 6.3 Results 6.3.1 The Zonal Climate Gradient 6.3.2 Acidic Versus Non-Acidic Tundra (Soil pH Zones) 6.3.3 The Toposequence at Happy Valley (Subzone E) 6.3.4 The Soil Moisture Gradient at Franklin Bluffs (Subzone D) 6.4 Discussion 6.4.1 Overview of Field Characterization and Spectral Properties along the Gradients 6.4.2 Performance of Spectral Metrics and Vegetation Indices 6.5 Conclusions 7 RESULTS OF THE SPECTRO-DIRECTIONAL REFLECTANCE INVESTIGATIONS 7.1 Overview of the Spectro-Directional Reflectance Characteristics of Low Arctic Tundra Vegetation 7.1.1 Representativeness of the Study Plots Representing Tundra Vegetation 7.1.2 Vaskiny Dachi – Bioclimate Subzone D 7.1.3 Happy Valley – Bioclimate Subzone E 7.1.4 Franklin Bluffs – Bioclimate Subzone D 7.2 Influence of High Sun Zenith Angles on the Reflectance Anisotropy 7.2.1 MAT (Happy Valley) 7.2.2 MNT (Franklin Bluffs) 7.3 Variability in Multi-Angular Remote Sensing Products of Low Arctic Tundra Environments 7.3.1 Spectro-Directional Variability of Different Low Arctic Plant Communities 7.3.2 Spectro-Directional Variability under Varying Sun Zenith Angles 8 DISCUSSION 8.1 The Hyperspectral Reflectance Characteristics of Tundra Vegetation in Context of the Spectro-Goniometer Measurements 8.2 Applicability of the ManTIS Field Spectro-Goniometer System 8.3 The Spectro-Directional Reflectance Characteristics of Tundra Vegetation 8.4 Variability in Reflectance Anisotropy at High Sun Zenith Angles 8.5 Applicability of Multi- Angular Remote Sensing Products for Arctic Tundra Environments 9 CONCLUSIONS & OUTLOOK Acknowledgments References Appendix Table of Contents of the Appendix References of the Appendix Statutory Declaration / Eidesstattliche Erklärung
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