ALBERT

Note: Dissertation, Universität Potsdam, 2017 , Table of Contents I. Abstract II. Deutsche Zusammenfassung 0 Challenge 1 Introduction 1.1 The treeline ecotone 1.2 Stand structure drivers in the treeline ecotone 1.3 Climate change and recent treeline changes 1.4 Methods for treeline studies 1.4.1 Overview 1.4.2 Field-based treeline studies 1.4.3 Modelling treeline dynamics 1.5 Study Area 1.6 The Siberian treeline ecotone 1.7 Larix as study Species 1.8 Objectives of this thesis 1.9 Thesis outline 1.10 Contribution of the authors 1.10.1 Manuscript!- published 1.10.2 Manuscript II - submitted 1.10.3 Manuscript III-in preparation 1.10.4 Manuscript IV-submitted 2 Manuscript I Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix 2.1 Abstract 2.2 Introduction 2.3 Materials and Methods 2.3.1 Reference sites 2.3.2 Description of the model LAVESI 2.3.3 The ODD-Protocol for LAVESI 2.3.4 Parameterization 2.3.5 Khatanga climate time-series 2.3.6 Sensitivity analysis 2.3.7 Model experiments 2.4 Results 2.4.1 Sensitivity analysis 2.4.2 Taymyr treeline application 2.4.3 Temperature experiments 2.5 Discussion 2.5.1 Assessment of LAVESI sensitivity 2.5.2 Larix stand simulation under the Taymyr Peninsula weather 2.5.3 Transient Larix response to hypothetical future temperature changes 2.5.4 Conclusions 2.6 Acknowledgements 3 Manuscript II Dissimilar responses of larch stands in northern Siberia to increasing temperatures - a field and simulation based study 3.1 Abstract 3.2 Introduction 3.3 Methods 3.3.1 Study area 3.3.2 Field-based approach 3.3.3 Age analyses 3.3.4 Stand structure analyses 3.3.5 Seed analyses 3.3.6 Establishment history 3.3.7 Modelling approach 3.4 Results 3.4.1 Field data 3.4.2 Simulation study 3.5 Discussion 3.5.1 Data acquisition 3.5.2 Larch-stand patterns across the Siberian treeline ecotone 3.5.3 Warming causes densification in the forest-tundra 3.5.4 Intra-specific competition inhibits densification in the closed forest 3.5.5 Recruitment limitation decelerates densification and northward expansion ofthe single-tree tundra 3.6 Conclusions 3.7 Acknowledgements 4 Manuscript III Spatial patterns and growth sensitivity of larch stands in the Taimyr Depression 4.1 Abstract 4.2 Introduction 4.3 Methods 4.3.1 Study Area 4.3.2 Field data collection 4.3.3 Spatial point patterns 4.3.4 Dendrological approach 4.4 Results 4.4.1 Spatial patterns 4.4.2 Tree growth 4.5 Discussion 4.5.1 Spatial patterns 4.5.2 Tree chronology characteristics 4.6 Conclusion 5 Manuscript IV Patterns of larch stands under different disturbance regimes in the lower Kolyma River area (Russian Far East) 5.1 Abstract 5.2 Introduction 5.3 Methods 5.3.1 Study area and field data collection 5.3.2 Site description 5.3.3 Dendrochronological approach 5.3.4 Statistical analyses 5.4 Results 5.4.1 General stand characteristics and age structure 5.4.2 Spatial patterns 5.5 Discussion 5.5.1 Fire related disturbances 5.5.2 Water-related disturbances: lake drainage, flooding, polygon development 5.5.3 Implications and conclusion 6 Synthesis and Discussion 6.1 Assessment of applied methods 6.1.1 Field-based observations: 6.1.2 Modelling 6.2 Overview of larch stand structures and spatial pattern on different spatial scales 6.2.1 Recent stand structures 6.2.2 Spatial Patterns 6.3 Stand structure drivers and treeline changes 6.3.1 Climate change 6.3.2 Disturbances 6.3.3 Autecology 6.4 Conclusion 6.5 Outlook 7 Appendix 7.1 Supplementary information for Manuscript I 7.2 Supplementary information for Manuscript II 7.2.1 Manuscript II: Appendix 1. Climatic information for the study region 7.2.2 Manuscript II: Appendix 2. Plot-specific values and krummholz appearance 7.2.3 Manuscript II: Appendix 3. Regression analysis for age data 7.2.4 Manuscript II: Appendix 4. Model description 7.3 Supplementary information for Manuscript III 7.4 Supplementary information for Manuscript IV 7.5 Supplementary information 8 References Danksagung Eidesstattliche Erklärung

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

Note: Table of Contents Abstract Zusammenfassung List of Figures List of Tables 1. Introduction 1.1 Scientific Background 1.1.1 Arctic Climate Change 1.1.2 Permafrost Degradation 1.1.3 The Arctic Freshwater System and its Biogeochemistry 1.2 Objectives 1.3 Study Region and Methods 1.3.1 Study Area 1.3.2 Field Sampling and Measurements 1.3.3 Geochemical Analyses 1.3.4 Data Processing 1.4 Thesis Structure 1.5 Author Contributions 2. Spatial Variability of Dissolved Organic Carbon, Solutes and Suspended Sediment in Disturbed Low Arctic Coastal Watersheds 2.1 Abstract 2.2 Introduction 2.3 Study Site 2.4 Methods 2.4.1 Stream Monitoring 2.4.2 Mapping of Disturbances 2.4.3 Flux Estimates and Statistics 2.5 Results 2.5.1 Catchment Disturbance 2.5.2 Runoff and Hydrochemistry 2.5.3 Lateral Transport of Stream Water 2.5.4 Hydrochemical Composition and Fluxes in Nearby Streams 2.6 Discussion 2.6.1 Total Runoff and Water Quality 2.6.2 Water Quality Changes from Headwaters to Downstream 2.6.3 Changes in Hydrochemistry and Isotopic Composition over Time 2.6.4 Importance of Disturbances for Hydrochemistry 2.7 Conclusions 2.8 Supplementary Material 3. Terrestrial Colored Dissolved Organic Matter (cDOM) in Arctic Catchments - Characterizing Organic Matter Composition Across the Arctic 3.1 Introduction 3.2 Study Area 3.3 Methods 3.3.1 Field Methods and Hydrochemistry 3.3.2 Statistical Analyses 3.4 Results 3.4.1 Meteorological Conditions and General Hydrochemistry 3.4.2 DOC and cDOM Absorption Characteristics 3.4.3 Downstream Patterns of DOC and cDOM Along Longitudinal Transects 3.4.4 Temporal Trends ofDOC and cDOM with Changing Meteorological Conditions 3.5 Discussion 3.5.1 Limitations of cDOM Measurements from Terrestrial Sources 3.5.2 Catchment Processes and Biogeochemical Cycling 3.5.2.1 Regional Catchment Properties 3.5.2.2 Rainfall Events 3.5.2.3 Downstream Patterns and Impact of Permafrost Disturbance 3.5.3 Nature of cDOM-DOC Across the Terrestrial Arctic 3.6 Conclusion 3.7 Supplementary Material 4. Summer Rainfall DOC, Solute and Sediment Fluxes in a Small Arctic Coastal Catchment on Herschel Island (Yukon Territory, Canada) 4.1 Abstract 4.2 Introduction 4.3 Study Site 4.4 Methodology 4.4.1 Weather data 4.4.2 Hydrology 4.4.3 Suspended Sediment and Hydrochemistry 4.4.4 Flux Estimates and Statistics 4.5 Results 4.5.1 Meteorological Conditions 4.5.2 Streamflow and Electrical Conductivity 4.5.3 Transport of Suspended Sediment and Organic Matter 4.5.4 Solute Transport 4.5.5 Alluvial Fan Sampling 4.6 Discussion 4.6.1 Hydrological Response 4.6.2 Water Quality and Fluxes 4.6.3 Rainfall Response and Flow Pathways 4.7 Conclusions 4.8 Supplementary Material 5. Synthesis 5.1 Impacts of Permafrost Degradation on Stream Biogeochemistry 5.2 Controls on DOM Quality across the Arctic 5.3 Biogeochemical Fluxes from Small Coastal Catchments to the Arctic Ocean 5.4 Challenges 5.5 Outlook Acronyms Bibliography Acknowledgements Eidesstattliche Erklärung

Note: Inhaltsverzeichnis 1 Einleitung 1.1Wissenschaftliche Zielsetzung 2 Grundlagen 2.1 Grundgleichungen 2.2 Potentielle Vorticity 2.3 Planetare Wellen 2.4 Atmosphärische Instabilität 2.5 Grenzschicht 2.6 Kopplung von Tropo- und Stratosphäre 3 Daten und Methoden 3.1 N-ICE2015 3.1.1 Expeditionsbeschreibung 3.1.2 Ziele der Expedition 3.2 Daten 3.2.1 Beobachtungsdaten 3.2.2 ERA-Interim Reanalyse 3.2.3 Das HIRHAM5 Modell 3.3 Analysemethoden 3.3.1 Temperaturinversionen 3.3.2 Vertikale Stabilität 3.3.3 Grenzschichthöhe 3.3.4 Eady Growth Rate 3.3.5 2d-Skalenfilterung und -Pattern-Korrelation 3.3.6 Nudging Experiment 4 Analyse der N-ICE2015 Radiosonden 4.1 Blick auf die Troposphäre 4.2 Fallstudie zum M2-Sturm: A 4.3 Zyklonencharakteristika 4.4 Temperaturinversionen und Stabilität 4.5 Vergleich mit ERA-Interim, SHEBA und Ny-Ålesund 4.6 Résumé der Expeditionsdaten 5 Nudging Studien mit HIRHAM5 5.1 Vergleich mit ERA-Interim 5.2 Vergleich der Simulationen 5.3 Fallstudie zum M2-Sturm: B 5.3.1 Synoptische Aktivität 5.4 Statistischer Vergleich 6 Einfluss der Stratosphäre 6.1 Stratosphäre im Winter 2014/2015 6.2 Fallstudie zum M2-Sturm: C 6.3 PV als Ladung 6.4 Résumé der Beobachtungen 7 Zusammenfassung und Ausblick A Zusätztliche Abbildungen B Literaturverzeichnis

Note: Table of contents Abstract Zusammenfassung Abbreviations and Nomenclature 1. Introduction 1.1 Scientific Background 1.1.1 Climate and Permafrost 1.1.2 Remote Sensing 1.1.3 Research Questions 1.2 General Approach 1.3 Thesis Structure 1.4 Author’ s contributions 1.4.1 Chapter 2 1.4.2 Chapter 3 1.4.3 Chapter 4 1.4.4 Chapter 5 1.4.5 Appendix Paper 1 2. Detection of landscape dynamics in the Arctic Lena Delta withtemporally dense Landsat time-series Stacks 2.1 Abstract 2.2 Introduction 2.3 Study Area and Data 2.3.1 Study Area 2.3.2 Data 2.3.3 Methods/processing 2.4 Results 2.4.1 Regional Scale changes 2.4.2 Local scale changes 2.5 Discussion 2.5.1 Regional scale changes 2.5.2 Local scale changes 2.5.3 Data quality 2.5.4 Data usage and outlook 2.6 Conclusion 2.7 Data Archive 2.8 Acknowledgements 2.9 Appendix A. Supplementary Data 3. Landsat-Based Trend Analysis of Lake Dynamics across NorthernPermafrost Regions 3.1 Abstract 3.2 Introduction 3.3 Study Sites 3.3.1 Alaska North Slope (NSL) 3.3.2 Alaska Kobuk-Selawik Lowlands (AKS) 3.3.3 Central Yakutia (CYA) 3.3.4 Kolyma Lowland (KOL) 3.4 Data and Methods 3.4.1 Data and Trend Analysis 3.4.2 Pixel-Based Machine-Leaming Classification 3.4.3 Object-Based Image Analysis 3.4.4 Data Quality and Post-Processing 3.4.5 Calculation of Lake Change Statistics 3.5 Results 3.5.1 NSL (Alaska North Slope) 3.5.2 AKS (Alaska Kobuk-Selawik Lowlands) 3.5.3 CYA (Central Yakutia) 3.5.4 KOL (Kolyma Lowland) 3.6 Discussion 3.6.1 Data Analysis 3.6.2 Comparison of Sites and Prior Studies 3.7 Conclusions 3.8 Supplementary Materials 3.9 Acknowledgements 3.10 Appendix A 4. Remotely sensing recent permafrost region disturbances across Arcticto Subarctic transects 4.1 Abstract 4.2 Introduction 4.3 Results 4.3.1 Lakes 4.3.2 Retrogressive Thaw Slumps 4.3.3 Wildfire 4.4 Discussion 4.5 Methods 4.5.1 Remote Sensing Data Processing 4.5.2 Auxiliary Data Sources 5. Tundra landform and Vegetation productivity trend maps for theArctic Coastal Plain of northern Alaska 5.1 Abstract 5.2 Background & Summary 5.3 Methods 5.3.1 Polygonal tundra geomorphology mapping 5.3.2 Image processing 5.3.3 Image Classification 5.3.4 Decadal scale NDVI trend analysis 5.4 Data Records 5.5 Technical Validation 5.5.1 Tundra Geomorphology Map 5.5.2 NDVI Trend Map 5.6 Data Citation 6. Discussion/Synthesis 6.1 Landsat-based trend analysis 6.1.1 Spatial Scale 6.1.2 Time series analysis 6.1.3 Model complexity 6.2 Mapping of permafrost landscape dynamics 6.2.1 Lake dynamics 6.2.2 Wildfire 6.2.3 Retrogressive Thaw Slumps 6.3 Pan-arctic scale distribution and consequences of changes inpermafrost 6.4 Outlook Bibliography A-1. Appendix: Reduced arctic tundra productivity linked with landform and climate change interactions A-1.1 Abstract A-1.2 Introduction A-1.3 Methods A-1.4 Results A-1.5 Discussion Danksagung/Acknowledgements Eidesstattliche Erklärung