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  • 1
    Call number: AWI Bio-20-93992
    Type of Medium: Dissertations
    Pages: XIII, 137 Seiten , Illustrationen, Diagramme , 1 CD-ROM
    Language: English
    Note: Dissertation, Universität Potsdam, 2017 , Content List of Abbreviations List of Figures List of Tables Summary Zusammenfassung Motivation Chapter 1 1. Scientific background 1.1 Late Quaternary climate changes and treeline transition in northern Siberia 1.2 Natural archives and proxies to assess vegetation history 1.3 Study area 1.3 Objectives of the thesis 1.4 Thesis outline 1.4.1 Chapters and manuscripts 1.4.2 Author's contribution 1.4.2.1 Manuscript I - published 1.4.2.2 Manuscript II - submitted 1.4.2.3 Manuscript III - prepared for submission Chapter 2 2. Manuscript I: Sedimentary ancient DNA and pollen reveal the composition of plant organic matter in Late Quaternary permafrost sediments of the Buor Khaya Peninsula (north-eastern Siberia) 2.1 Abstract 2.2 Introduction 2.3 Geographical settings 2.4 Material and methods 2.4.1 Core material 2.4.2 Subsampling of the permafrost core 2.4.3 Molecular genetic laboratory work 2.4.4 Analysis of sequence data and taxonomic assignments 2.4.5 Pollen sample treatment and analysis 2.4.6 Statistical analyses and visualization 2.5 Results 2.5.1 SedaDNA 2.5.1.1 SedaDNA of terrestrial plants 2.5.1.2 SedaDNA of swamp and aquatic plants 2.5.1.3 SedaDNA of bryophytes and algae 2.5.2 Pollen 2.5.2.1 Pollen of terrestrial plants 2.5.2.2 Pollen and spores of swamp and aquatic plants 2.5.2.3 Spores and algae 2.5.3 Ratios of terrestrial to swamp and aquatic taxa and Poaceae to Cyperaceae 2.6 Discussion 2.6.1 Quality and proxy value of sedaDNA and pollen data 2.6.2 Environmental conditions during the pre-LGM (54-51 kyr BP, 18.9-8.35 m) and composition of deposited organic matter 2.6.3 Environmental conditions during the post-LGM (11.4-9.7 kyr BP (13.4-11.1 cal kyr BP)) and composition of deposited organic matter 2.7 Conclusions 2.8 Acknowledgements Chapter 3 3. Manuscript II: Genetic variation of larches at the Siberian tundra-taiga ecotone inferred from the assembly of chloroplast genomes and mitochondrial sequences 3.1. Abstract 3.2. Introduction 3.3. Material and methods 3.3.1 Plant material 3.3.2 DNA isolation and sequencing 3.3.3 Sequence processing and de novo assembly 3.3.4 Chloroplast genome assembly, annotation and variant detection 3.3.5 Mitochondrial sequences 3.3.6 Analyses of genetic variation 3.4 Results 3.4.1 Chloroplast genome structure and genetic variation 3.4.2 Mitochondrial sequences and genetic variation 3.5 Discussion 3.5.1 De novo assembly and genetic variation of chloroplast genomes and mitochondrial sequences 3.5.2 The distribution of genetic variation at the tundra-taiga ecotone 3.6 Conclusions 3.7 Acknowledgements Chapter 4 4. Manuscript III: The history of tree and shrub taxa and past genetic variation of larches on Bol'shoy Lyakhovsky Island (New Siberian Archipelago) since the last interglacial uncovered by sedimentary ancient DNA 4.1 Abstract 4.2 Introduction 4.3 Materials and methods 4.3.1 Geographic setting 4.3.2 Core material 4.3.2.1 Core L14-02: Yedoma Ice Complex 4.3.2.2 Core L14-03: Thermo terrace 4.3.2.3 Core L14-04 and hand-pieces L14-04B and L14-04C: Thermo terrace including Eemian deposits 4.3.2.4 Core L14-05: Alas 4.3.3 Core sub-sampling 4.3.4 Molecular genetic laboratory work 4.3.4.1 Sedimentary ancient DNA metabarcoding approach 4.3.4.2 Specific amplification of Larix from sedimentary ancient DNA 4.3.5 Filtering of Illumina sequencing data and taxonomic assignments 4.3.6 Statistical analyses and visualization 4.3.7 Geochronology 4.4. Results 4.4.1 Overall composition of the DNA metabarcoding data 4.4.2 Terrestrial vegetation composition 4.4.2.1 Core L14-02: Late Pleistocene Yedoma Ice Complex 4.4.2.2 L14-03: Deeper late Pleistocene deposits 4.4.2.3 L14-04 Thermo terrace including Eemian deposits 4.4.2.4 Core L14-05: Alas with Holocene lake deposits and taberits of the Yedoma Ice Complex 4.4.2.5 The multivariate structure of the terrestrial vegetation among samples and cores 4.4.3 Genetic variation ofsediment-derived Larix sequences 4.5 Discussion 4.5.1 Tree taxa in the sedaDNA record - where do they come from? 4.5.2 Terrestrial plant community changes of warm phases since the last interglacial 4.5.3 Past genetic diversity of larch populations on Bol'shoy Lyakhovsky Island 4.6 Conclusion 4.7 Acknowledgements Chapter 5 5. Synopsis 5.1 The proxy potential of sedaDNA in paleobotanical reconstructions from sedimentary deposits 5.1.1 Combining sedaDNA and pollen to assess plant diversity and vegetation composition 5.1.2 Current limits and opportunities of sedaDNA approaches 5.2 Using genomic data to trace modern and past treeline dynamics 5.2.1 Modern genomic variation at the Siberian treeline 5.2.2 PCR-based markers for paleoenvironmental genetics 5.3 Terrestrial plant community changes and treeline dynamics in north-eastern Siberia since the last interglacial 5.3.1 Vegetation changes in north-eastern Siberia since the last interglacial 5.3.2 Implications for treeline dynamics 5.4 Conclusion 5.5 Outlook Appendix 1. Supplementary material for Manuscript I (Chapter 2) 2. Supplementary material for Manuscript II (Chapter 3) 3. Supplementary material for Manuscript III (Chapter 4) References Acknowledgements Erklärung
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  • 2
    Call number: AWI Bio-20-93994
    Type of Medium: Dissertations
    Pages: viii, 140 Seiten , Illustrationen, Diagramme
    Language: English
    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
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  • 3
    Call number: AWI G5-20-93989
    Type of Medium: Dissertations
    Pages: viii, 139 Seiten , Illustrationen, Diagramme
    Language: English
    Note: Dissertation, Universität Potsdam, 2018 , Table of Content I. Abstract II. Deutsche Zusammenfassung 0 Preface 1 Scientific Background 1.1 Paleoenvironmental changes since the gLGM in arid Central Asia and north-western High Asia 1.1.1 Paleoclimatic changes 1.1.2 Lake level fluctuations following climatic changes 1.1.3 Inferred terrestrial vegetation responses to environmental changes and possible human impact 1.2 The role of proxy records in tracing environmental changes 1.2.1 Archives and Proxies investigated in environmental studies in Central Asia 1.2.2 Limnological systems as environmental archives 1.2.3 The multiproxy approach as a tool to decipher environmental change 1.3 Study area 1.4 Material and Method Overview 1.4.1 Field based sampling 1.4.2 Outline of material and methods 1.5 Aim and objectives ofthis thesis 1.6 Thesis outline 1.7 Contribution of the authors 1.7.1 Manuscript I - published 1.7.2 Manuscript II - published 1.7.3 Manuscript III - published 1.7.4 Manuscript IV - in preparation 2 Manuscript I Climatic and limnological changes at Lake Karakul (Tajikistan) during the last ~29 cal ka 2.1 Abstract 2.2 Introduction 2.3 Study Area 2.4 Material and methods 2.4.1 Fieldwork 2.4.2 Laboratory analysis 2.5 Results 2.5.1 Age-depth relationship in core KK12-1 2.5.2 TIC, TOC, TOC/TN, δ18Ocarb and δ13CCarb 2.5.3 Grain-size distribution and results ofend-member modelling 2.5.4 XRF data 2.5.5 Ordination results of sediment parameters 2.6 Discussion 2.6.1 Paleoenvironmental indicators from sediment variables 2.6.2 Implications ofthe Lake Karakul sediment record 2.6.3 Linking lake internal development to climate change 2.7 Conclusions 2.8 Acknowledgements 2.9 Data availability 3 Manuscript II Aquatic macrophyte dynamics in Lake Karakul (Eastern Pamir) over the last 29 cal ka revealed by sedimentary ancient DNA and geochemical analyses of macrofossil remains 3.1 Abstract 3.2 Introduction 3.3 Material and Methods 3.3.1 Sample acquisition and treatment 3.3.2 Genetic approach 3.3.3 Elemental isotopic analyses ofaquatic macrophyte remains 3.4 Results 3.4.1 Macrophyte records along lake depth transects in Lake Karakul 3.4.2 Submerged plant content 3.4.3 Ancient DNA analyses 3.4.4 C, N, δ13C and δ15N of Stuckenia cf. pamirica remains 3.5 Discussion 3.5.1 Assessment of aDNA and chemical aquatic macrophyte data as proxies for the macrophyte composition and the paleo-productivity 3.5.2 Changes of past submerged plant composition and productivity and potential drivers 3.6 Conclusions 3.7 Acknowledgements 3.8 Data Availability 4 Manuscript III Radiocarbon and optical stimulated luminescence dating of sediments from Lake Karakul, Tajikistan 4.1 Abstract 4.2 Introduction 4.3 Regional setting 4.4 Methods 4.4.1 Collection and correlation of cores 4.4.2 Radiocarbon dating 4.4.3 Optically stimulated luminescence (OSL) dating 4.4.4 Establishment ofage-depth model 4.4.5 Investigation of exposed lake sediments 4.5 Results 4.6 Discussion 4.6.1 Recovered sediments and correlation ofcores from Lake Karakul 4.6.2 Age-depth model, and assessment of radiocarbon and OSL age data 4.6.3 Significance ofexposed sediments at section KK13-S1 4.6.4 Implications ofthe chronological data 4.7 Conclusion 4.8 Acknowledgements 5 Manuscript IV Vegetation change in the Eastern Pamir Mountains inferred from Lake Karakul pollen spectra of the last 28 ka 5.1 Abstract 5.2 Introduction 5.3 Study site 5.4 Material and Methods 5.4.1 Sediment cores and chronology 5.4.2 Pollen sample preparation and pollen analyses 5.4.3 Pollen data treatment 5.5 Results 5.5.1 Composite core (KK12-1/2; 27.6 cal ka BP to present) 5.5.2 Short core TAJ-Kar-08-lB 5.6 Discussion 5.6.1 Interpretation of pollen data 5.6.2 Terrestrial vegetation change in the Eastern Pamir Mountains in response to past climate change 5.7 Conclusions 5.8 Acknowledgements 5.9 Data Availability 6 Synthesis 6.1 Proxy evaluation 6.1.1 Age-depth relationship 6.1.2 Limnological proxies 6.1.3 Terrestrial proxies 6.2 The potential of Lake Karakul as archive for long term environmental change in the Eastern Pamir 6.3 Climate and moisture availability changes over time - inferred from sedimentary proxies 6.4 Assessment ofthe aquatic macrophyte composition and paleoproductivity within Lake Karakul 6.5 Inferred terrestrial vegetation changes as responds to climatic changes over the last 28 cal ka 6.6 Comparison inferred regional vegetation, lake internal and lake external variations and changes in climate reconstructed in other studies 6.6.1 Pre- gLGM and global Last Glacial Maximum (27.6 to 19 cal ka BP) 6.6.2 Late glacial 6.6.3 Early to middle Holocene 6.6.4 Middle to late Holocene 6.7 Outlook 7 Appendix 7.1 Supplementary information for Manuscript I 7.2 Supplementary information for Manuscript II 7.3 Supplementary information for Manuscript III 8 References Danksagung Eldesstattliche Erklärung
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  • 4
    Call number: AWI Bio-20-93993
    Type of Medium: Dissertations
    Pages: III, 127 Seiten , Illustrationen
    Language: English
    Note: Dissertation, Universität Potsdam, 2014 , Table of contents I - Abstract II - Zusammenfassung Chapter 1 - Introduction 1.1. Introduction 1.1.1 Motivation 1.1.2 Organisation of thesis 1.1 Scientific background 1.2.1 Arctic and wetland bryophytes 1.2.2 Bryophyte remains as palaeo-environmental indicators 1.2.3 Regional setting 1.3 Objectives ofthe thesis 1.4 Overview of the manuscripts 1.5 Contribution of the authors Chapter 2 - Manuscript #1 Abstract 2.1 Introduction 2.2 Geographic setting 2.3 Materials and methods 2.3.1 Fieldwork 2.3.2 Radiocarbon dating 2.3.3 Geochemical, stable carbon isotope, and granulometric analyses 2.3.4 Analyses of moss remains and vascular plant macrofossils 2.3.5 Pollen analysis 2.3.6 Diatom analysis 2.3.7 Statistical analysis 2.4 Results 2.4.1 High-resolution spatial characteristics oft the investigated polygon and vegetation pattern 2.4.2 Geochronology and age-depth relationships 2.4.3 General properties of the sedimentary fill 2.4.4 Bioindicators 2.4.5 Characterization oftwo different types of polygon pond sediment 2.5. Discussion 2.5.1 Small-scale spatial structure of polygons 2.5.2 Age-depth relationships 2.5.3 Proxy value of the analysed parameters 2.5.4 The general polygon development 2.5.5 Polygon development as a function of external controls and internal adjustment mechanisms 2.6 Conclusions Chapter 3 - Manuscript #11 Abstract 3.1 Introduction 3.2 Material und methods 3.2.1 Regional setting 3.2.3 Field methods and environmental data collection 3.2.4 Data analysis 3.3 Results 3.3.1 Major characteristics of the investigated polygons 3.3.2 Vegetation cover and its relationships with micro-relief and vegetation type 3.3.3 Vegetation alpha-diversity and its relationship with micro-relief and vegetation type 3.3.4 Vegetation composition and its relationship with micro-relief and vegetation type 3.4 Discussion 3.4.1 Patterns of cover, alpha-diversity and compositional turnover of vascular plants and bryophytes along the rim-pond transect (local-scale) 3.4.2 Patterns of cover, alpha-diversity and compositional turnover of vascular plants and bryophytes along the regional-scale forest-tundra transect 3.4.3 Indicator potential ofvascular plant and bryophyte remains from polygonal peats for the reconstruction of local hydrological and regional vegetation changes 3.4.4. Implications of the performed vegetation transect studies for future Arctic warming 3.5 Acknowledgements 2.4.4 Bioindicators 2.4.5 Characterization of two different types of polygon pond sediment 2.5. Discussion 2.5.1 Small-scale spatial structure of polygons 2.5.2 Age-depth relationships 2.5.3 Proxy value of the analysed parameters 2.5.4 The general polygon development 2.5.5 Polygon development as a function of external controls and internal adjustment mechanisms 2.6 Conclusions Chapter 3 - Manuscript #II Abstract 3.1 Introduction 3.2 Material und methods 3.2.1 Regional setting 3.2.3 Field methods and environmental data collection 3.2.4 Data analysis 3.3 Results 3.3.1 Major characteristics of the investigated polygons 3.3.2 Vegetation cover and its relationships with micro-relief and vegetation type 3.3.3 Vegetation alpha-diversity and its relationship with micro-relief and vegetation type 3.3.4 Vegetation composition and its relationship with micro-relief and vegetation type 3.4 Discussion 3.4.1 Patterns of cover, alpha-diversity and compositional turnover of vascular plants and bryophytes along the rim-pond transect (local-scale) 3.4.2 Patterns of cover, alpha-diversity and compositional turnover of vascular plants and bryophytes along the regional-scale forest-tundra transect 3.4.3 Indicator potential of vascular plant and bryophyte remains from polygonal peats for the reconstruction of local hydrological and regional vegetation changes 3.4.4. Implications of the performed vegetation transect studies for future Arctic warming 3.5 Acknowledgements Chapter 4 - Manuscript #3 Abstract 4.1 Introduction 4.2 Material and methods 4.2.1 Sites 4.2.2 Sampling 4.2.3 Investigated moss species 4.2.4 Measurements 4.2.5 Statistical Tests 4.3 Results 4.4 Discussion Chapter 5 - Discussion 5.1 Bryophytes of polygonal landscapes in Siberia 5.1.1 Modern bryophytes in the Siberian Arctic 5.1.2 Biochemical and isotopic characteristics of mosses 5.1.3 Reliability and potential of fossil bryophyte remains as palaeoproxies 5.2 Dynamics of low-centred polygons during the late Holocene 5.3 Outlook Appendix I - Preliminary Report Motivation Material and methods Results and first interpretation Appendix II Additional tables and figures of manuscript #1 Appendix III Additional figures of manuscript #2 Appendix IV - Quantitative approach of Standard Moss Stem (SMS3) Bibliography Acknowledgements Eidesstattliche Erklärung
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  • 5
    Call number: AWI Bio-20-93988
    Type of Medium: Dissertations
    Pages: x, 181 Seiten , Illustrationen, Diagramme
    Language: English
    Note: Dissertation, Universität Potsdam, 2017 , Contents Abstract Kurzfassung Contents 1. List of figures 2. List of tables Chapter 1. General introduction 1. Motivation 2. Scientific background 3. Objectives of the thesis 4. Thesis outline Chapter 2. Manuscript 1: Treeline dynamics in Siberia under changing climates as inferred from an individual-based model for Larix 1. Abstract 2. Introduction 3. Material and Methods 4. Results 5. Discussion 6. Acknowledgements Chapter 3. Manuscript 2: Field and simulation data reveal dissimilar responses of Larix gmelinii stands to increasing temperature across the Siberian treeline ecotone 1. Abstract 2. Introduction 3. Methods 4. Results 5. Discussion 6. Acknowledgements Chapter 4. Manuscript 3: High gene flow and complex treeline dynamics on the Taymyr Peninsula (north-central Siberia), revealed by nuclear microsatellites of Larix 1. Abstract 2. Introduction 3. Materials and methods 4. Results 5. Discussion 6. Acknowledgements Chapter 5. Manuscript 4: Dispersal distances at treeline in Siberia - genetic guided model improvement 1. Abstract 2. Introduction 3. Methods 4. Results 5. Discussion 6. Acknowledgements Chapter 6. Synopsis 1. Towards a better understanding of Siberian treeline dynamics 2. Methodological challenges to reconstruct and predict the treeline advance 3. Conclusions 4. Outlook Appendix 1. Supplementary information for manuscript 1 (Chapter 2) 2. Supplementary information for manuscript 2 (Chapter 3) 3. Supplementary information for manuscript 3 (Chapter 4) 4. Supplementary information for manuscript 4 (Chapter 5) Bibliography Acknowledgements - Danksagung Declaration
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  • 6
    Call number: AWI G5-22-94780
    Type of Medium: Dissertations
    Pages: xxi, 201 Seiten , Illustrationen, Diagramme
    Language: English
    Note: Dissertation, Universität Potsdam, 2021 , Contents List of Figures List of Tables I Preamble 1 Introduction 1.1.1 The Journey from Weather to Climate 1.1.2 The Climate Background 1.1.3 Pollen as Quantitative Indicators of Past Changes 1.2 Overview and Aims of Manuscripts 1.2.1 List of Manuscripts 1.2.2 Short Summaries of the Manuscripts 1.3 Author Contributions to the Manuscripts II Manuscripts 2 Comparing estimation of techniques for temporal Scaling 2.1 Introduction 2.2 Data and Methods 2.2.1 Scaling estimation methods 2.2.2 Evaluation of the estimators 2.2.3 Data 2.3 Results 2.3.1 Effect of Regular and Irregular Sampling 2.3.2 Effect of Time series length 2.3.3 Application to database 2.4 Discussion 2.5 Conclusions 3 Land temperature variability driven by oceans at millennial timescales 4 Variability of surface climate in simulations of past and future 4.1 Introduction 4.2 Data and Method 4.2.1 Model simulations 4.2.2 The Last Glacial Maximum experiment 4.2.3 The mid Holocene experiment (midHolocene) 4.2.4 The warming experiments 1pctCO2 and abrupt4xCO2 4.2.5 Preprocessing of model simulations 4.2.6 Comparisons across the ensemble 4.2.7 Diagnosing variability changes 4.2.8 Changes in precipitation extremes 4.2.9 Timescale-dependence of the variability changes 4.3 Results 4.3.1 Hydrological sensitivity across the ensemble 4.3.2 Changes in local interannual variability 4.3.3 Changes in modes of variability 4.3.4 Circulation patterns underlying extratropical precipitation extremes 4.3.5 Changes in. the spectrum of variability 4.4 Discussion 4.4.1 Changes in climate variability with global mean temperature 4.4.2 Temperature vs. precipitation scaling 4.4.3 Comparison to climate reconstructions and observations 4.4.4 Limitations 4.5 Conclusions 5 Holocene vegetation variability in the Northern Hemisphere 5.1 Introduction 5.2 Data and Methods 5.2.1 Pollen Database 5.2.2 Principal Component Analysis 5.2.3 Timescale-dependent Estimates of Variability 5.2.4 Biome Classification 5.3 Results 5.3.1 General Vegetation Variability Analysis 5.3.2 Comparison of Forested and Open Land Vegetations 5.3.3 Comparison of Broadleaf and Needleleaf Fore ts 5.3.4 Comparison of Temperate and Boreal Coniferous Forests 5.3.5 Comparison of Evergreen and Deciduous Boreal Forests 5.4 Discussion 5.5 Conclusion III Postamble 6 General discussion and conclusion 6.1 Overview 6.2 Timescale-Dependent Estimates of Variability 6.3 Climate and Vegetation Variabilities in the Holocene 6.4 Implications for the 21th Century 6.5 Outlook IV Appendix A Supplementary figures from "Comparing estimation techniques for temporal scaling in paleo-climate timeseries" A.1 Block Average Results A.2 First-Order Correction for the Effect of Interpolation A.3 Change in Bias and Standard Deviation B Methods and supplementary information from "Land temperature variability driven by oceans at millennial timescales" B.1 Methods B.1.1 Reconstructions B.1.2 Significance Testing B.1.3 Testing for Anthropogenic Impacts B.1.4 Instrumental Data B.1.5 Model Data B.1.6 Spectral Estimates B.1.7 Variance Ratios B.1.8 Sub-Decadal Variability Binning B.1.9 Correlation B.1.10 Moran's I B.2 Supplementary Information B.2.1 Tree Ring Data Analysis B.2.2 Energy-Balance Equations B.3 Extended Data Figures C Supplementary figures from "Variability of surface climate in simulations of past and future" D Supplementary figures from "Characterization of holocene vegetation variability in the Northern Hemisphere" Bibliography
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  • 7
    Call number: AWI Bio-22-94840
    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.
    Type of Medium: Dissertations
    Pages: 149 Seiten , Illustrationen, Diagramme
    Language: English
    Note: Dissertation, Potsdam, Universität Potsdam, 2022 , Contents Abstract Zusammenfassung Contents Abbreviations Motivation 1 Introduction 1.1 Scientific background 1.2 Study region 1.3 Aims and objectives 2 Materials and methods 3.1 Section 4 - Strong shrub expansion in tundra-taiga, tree infilling in taiga and stable tundra in central Chukotka (north-eastern Siberia) between 2000 and 2017 3.2 Section 5 - Recent above-ground biomass changes in central Chukotka (NE Siberia) combining field-sampling and remote sensing 3.3 Section 6 - Future spatially explicit tree above-ground biomass trajectories revealed for a mountainous treeline ecotone using the individual-based model LAVESI 4 Strong shrub expansion in tundra-taiga, tree infilling in taiga and stable tundra in central Chukotka (north-eastern Siberia) between 2000 and 2017 Abstract 1 Introduction 2 Materials and methods 2.1 Field data collection and processing 2.2 Landsat data, pre-processing and spectral indices processing 2.3 Redundancy analysis (RDA) and classification approaches 3 Results 3.1 General characteristics of the vegetation field data 3.2 Relating field data to Landsat spectral indices in the RDA model 3.3 Land-cover classification 3.4 Land-cover change between 2000 and 2017 4 Discussion 4.1 Dataset limitations and optimisation 4.2 Vegetation changes from 2000/2001/2002 to 2016/2017 Conclusions Acknowledgements Data availability statement References Appendix A. Detailed description of Landsat acquisitions Appendix B. MODIS NDVI time series from 2000 to 2018 Appendix C. Landsat Indices values for each analysed vegetation site Appendix D. Fuzzy c-means classification for interpretation of uncertainties for land-cover mapping Appendix E. Validation of land-cover maps Appendix F. K-means classification results Appendix G. Heterogeneity of natural landscapes and mixed pixels of satellite data Appendix H. Distribution of land-cover classes and their changes by study area 5 Recent above-ground biomass changes in central Chukotka (NE Siberia) combining field-sampling and remote sensing Abstract 1 Introduction 2 Materials and methods 2.1 Study region and field surveys 2.2 Above-ground biomass upscaling and change derivation 3 Results 3.1 Vegetation composition and above-ground biomass 3.2 Upscaling above-ground biomass using GAM 3.3 Change of above-ground biomass between 2000 and 2017 in the four focus areas 4 Discussion 4.1 Recent state of above-ground biomass at the field sites 4.2 Recent state of above-ground biomass upscaled for central Chukotka 4.3 Change in above-ground biomass within the investigated 15–16 years in central Chukotka 5 Conclusions Data availability statement Author contributions Competing interests Acknowledgements References Appendix A. Sampling and above-ground biomass (AGB) calculation protocol for field data 6 Future spatially explicit tree above-ground biomass trajectories revealed for a mountainous treeline ecotone using the individual-based model LAVESI Abstract 1 Introduction 2 Materials and methods 2.1 Study region 2.2 LAVESI model setup, parameterisation, and validation 2.2.4 LAVESI simulation setup for this study 2.2.5 Validation of the model’s performance 3 Results 3.1 Dynamics and spatial distribution changes of tree above-ground-biomass 3.2 Spatial and temporal validation of the contemporary larch AGB 4 Discussion 4.1 Future dynamics of tree AGB at a plot level 4.2 What are the future dynamics of tree AGB at the landscape level? 5 Conclusions Data availability Acknowledgements References Appendix B. Permutation tests for tree presence versus topographical parameters Appendix C. Landsat-based, field, and simulated estimations of larch above-ground biomass (AGB). 7 Synthesis 7.1 What changes in vegetation composition have happened from 2000 to 2017 in central Chukotka? 7.2 How have the above-ground biomass (AGB) distribution and rates changed from 2000 to 2017 in central Chukotka? 7.3 What are the spatial dynamics and rates of tree AGB change in the upcoming centuries in the northern tundra-taiga from 2020 to 3000 CE on the plot level and landscape level? References Acknowledgements
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  • 8
    Call number: AWI Bio-22-95014
    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.
    Type of Medium: Dissertations
    Pages: x, 121 Seiten , Illustrationen
    Language: English
    Note: Dissertation, Universität Potsdam, 2022 , Table of Contents Summary Deutsche Zusammenfassung Table of Contents 1 Introduction 1.1 Larix forests in a changing climate 1.2 The genus Larix 1.3 Larix distribution in the world and their dominance in northern Asia 1.4 Methods to study past species dynamics 1.4.1 Modern genetic marker studies 1.4.2 Lake sediments as archives of the past 1.4.3 Pollen and macrofossils 1.4.4 Metabarcoding of sedimentary ancient DNA 1.4.5 Metagenomic shotgun sequencing 1.4.6 Target enrichment by hybridization capture 1.5 Thesis Objectives 1.6 Thesis outline & author contributions 2 Manuscript I 2.1 Abstract 2.2 Introduction 2.3 Material and methods 2.3.1 Bioclimatic limits 2.3.2 Pollen, macrofossil, and DNA datasets 2.3.3 Ice sheets 2.4 Results 2.4.1 Bioclimatic limits of Larix and its distribution on permafrost 2.4.2 Glacial occurrence patterns of Larix 2.5 Discussion 2.5.1 Are differences in species bioclimatic limits responsible for disparity in Larix distribution across continents? 2.5.2 Do high latitude glacial refugia guarantee larch dominance? 2.5.3 What role does postglacial migration play in larch dominance? 2.5.4 Fire as an additional factor 2.5.5 Outlook 2.6 Conclusion 2.7 Acknowledgements 2.8 Author contributions 2.9 References 3 Manuscript II 3.1 Abstract 3.2 Introduction 3.3 Methods 3.3.1 Sample material 3.3.2 Laboratory work 3.3.3 Data analysis 3.4 Results 3.4.1 Overview of the shotgun and hybridization capture data sets 3.4.2 Ancient DNA authenticity 3.4.3 Retrieval of the Larix chloroplast genome 3.5 Discussion 3.5.1 Taxonomic classification—conservative approach results in low numbers of assignment 3.5.2 Target enrichment success—Larix reads increased by orders of magnitude along with other taxonomic groups 3.5.3 Complete retrieval of ancient Larix chloroplast genomes 3.5.4 Larix sibirica variants present over time 3.5.5 Larch forest decline over the last 7000 years 3.6 Conclusion 3.7 Acknowledgments 3.8 Author contributions 3.9 References 4 Manuscript III 4.1 Abstract 4.2 Introduction 4.3 Results & Discussion 4.3.1 Chloroplast and repetitive DNA enrichment in the sedaDNA samples 4.3.2 A wider pre-glacial distribution of L. sibirica 4.3.3 Larix gmelinii formed northern LGM refugia across Siberia 4.3.4 Postglacial colonization history - differences among larch species 4.3.5 Environment likely plays a more important role than biogeography 4.4 Conclusion 4.5 Material & methods 4.5.1 Sample material 4.5.2 Sequence data analysis 4.6 Data availability 4.7 Acknowledgments 4.8 Author contributions 4.9 References 5 Discussion and synthesis 5.1 Hybridization capture is a well-suited method to study ancient species dynamics 5.1.1 Advantages and limitations of shotgun sequencing 5.1.2 Successful hybridization capture enrichment using chloroplast DNA 5.1.3 Challenges in single-copy target enrichment 5.1.4 Limitations and potentials to improve sedaDNA capture studies 5.2 Factors promoting Asian larch dominance 5.3 Drivers of Larix species distribution 5.3.1 Implications for larch forests under climate warming 5.4 Conclusion 5.5 Outlook 6 References 7 Appendix 7.1 Appendix to manuscript I 7.2 Appendix to manuscript II 7.3 Appendix to manuscript III 7.3.1 Material and Methods 7.3.2 Additional Results & Discussions 7.3.3 References Acknowledgements Eidesstattliche Erklärung
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  • 9
    Call number: AWI Bio-22-94767
    Type of Medium: Dissertations
    Pages: XVIII, 165 Seiten , Illustrationen, Diagramme
    Language: English
    Note: Dissertation, Universität Potsdam, 2021 , Table of Contents Acknowledgements Abstract Zusammenfassung List of figure List of tables List of abbreviation Chapter 1 1. Introduction 1.1 Research background 1.1.1 Response of mountain plant diversity to climate change 1.1.2 Response of Arctic vegetation composition and diversity to climate change 1.1.3 Understanding the critical mechanisms of community assembly are essential for sustaining ecosystem services 1.1.4 Pollen analysis as a traditional tool for representing palaeovegetation 1.1.5. Sedimentary ancient DNA (sedaDNA) is a useful tool for Quaternary ecology tracking 1.2 Study area 1.3 Aims and objectives 1.4 Structure of the thesis 1.4.1 Overview of the chapter 1.4.2 Author's contributions 1.4.3 Methods Chapter 2 2 Manuscript 1: Sedimentary ancient DNA reveals warming-induced alpine habitat loss threat to Tibetan Plateau plant diversity 2.1 Abstract 2.2 Introduction 2.3 Results and discussion 2.4 Methods 2.5 Acknowledgements · Chapter 3 3 Manuscript 2: Holocene vegetation and plant diversity changes in the north-eastern Siberian treeline region from pollen and sedimentary ancient DNA 3.1 Abstract 3.2 Introduction 3.3 Materials and methods 3.3.1 Study area 3.3.2 Lake sediment cores and subsampling 3.3.3 Dating 3.3.4 Pollen analysis 3.3.5 DNA extraction and amplification 3.3.6 Sequencing filtering and taxonomic assignment 3.3.7 Statistical analyses 3.4 Results 3.4.1 Chronology 3.4.2 SedaDNA and pollen assemblages 3.4.3 Gradient analysis and correlation analysis 3.5 Discussion 3 .5.1 Contributions of pollen and sedaDNA to vegetation reconstruction and taxon richness 3.5.2 Variation in Holocene vegetation composition in the Omoloy area, north-eastern Siberia 3.5.3 SedaDNA-based plant diversity changes within lake catchments of the Omoloy region 3.6 Conclusions 3.7 Acknowledgements Chapter 4 4 Manuscript 3: Vegetation reconstruction from Siberia and Tibetan Plateau using modern analogue technique - comparing sedimentary ancient DNA (sedaDNA) and pollen data 4.1 Abstract 4.2 Introduction 4.3 Materials and methods 4.3.1 Sites ofthe modern analogues 4.3.2 Sedimentary (ancient) DNA collection 4.3.3 Metabarcoding data processing and filtering 4.3.4 Pollen data collection 4.3.5 Numerical analysis 4.4 Results 4.4.1 Modern training-set, ROC curve analyses and AT results 4.4.2 Modern analogues for Lake Naleng and Omoloy lake II 4.4.3 Vegetation type reconstruction based on MAT 4.4.4 Projecting fossil samples in ordination space of modern assemblages 4.4.5 Comparing past and present intertaxa relationships 4.5 Discussion 4.5.1 Assessment of analogue quality using modem training-sets 4·5·2 Comparison of sed(a)DNA-based and pollen-based vegetation reconstruction for the Lake Naleng, Tibetan Plateau 4.5.3 Comparison of sedDNA based and pollen-based vegetation reconstruction for the Lake Omoloy, northern Siberia 4.6 Conclusions 4.7 Acknowledgements Chapter 5 5 Manuscript 4: Terrestrial-aquatic ecosystem links on the Tibetan Plateau inferred from sedaDNA shotgun sequencin 5.1 Abstract 5.2 Introduction 5.3 Results 5.4 Discussions 5.5 Methods 5.6 Acknowledgments Chapter 6 6 Synthesis 6.1 The ability of metabarcoding and metagenomic shotgun sequencing to reveal ecological community pattern 6.2 Driver of plant diversity change in high altitude and high latitudes 6.3 High-altitude and high-latitude vegetation type change 6.4 Past terrestrial and aquatic ecological change at ecosystem-scale 6.5 Conclusions and outlook Appendix 1 Appendix-1 Materials for Manuscript #1 1.1 Appendix discussion: Contamination in NTC6 2. Appendix-2 Materials for Manuscript #2 3. Appendix-3 Materials for Manuscript #3 4. Appendix-4 Materials for Manuscript #4 References Eidesstattliche Erklarung
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  • 10
    Call number: AWI Bio-22-94766
    Description / Table of Contents: The arctic-boreal treeline is a transition zone from taiga to tundra covering a vast area in Siberia. It often features large environmental gradients and reacts sensitively to changes in the environment. For example, the expansion of shrubs and a northward movement of the treeline are observable in Siberia as a response to the warming climate. The changes in vegetation across the treeline are known to influence the water chemistry in the lakes. This causes further alteration to the composition and diversity of sensitive aquatic organisms such as diatoms and macrophytes. Despite the rising awareness of the complex climate-feedback mechanisms of terrestrial plants, the understanding of their assembly rules and about responses of aquatic biomes in the surrounding treeline lakes is still limited. The goal of this thesis is to examine the previous and present biodiversity of terrestrial and freshwater biomes from the Siberian treeline ecotone, as well as their reactions to environmental changes. In particular, this thesis attempts to ...
    Type of Medium: Dissertations
    Pages: 132 Blätter , Illustrationen, Diagramme, Karten
    Language: English
    Note: Dissertation, Universität Potsdam, 2021 , Contents List of abbreviations Acknowledgements Summary Zusammenfassung 1 Scientific background 1.1 Motivation 1.2 The arctic-boreal ecotone in time and space 1.2.1 Terrestrial plants composition and biodiversity 1.2.2. Lake macrophytes and diatoms 1.3 Sedimentary DNA metabarcoding as an ecologicalproxy 1.4 Study area 1.5 Objectives of the thesis 1.6 Methods 1.7 Thesis organizations 1.7.1 Manuscripts and chapters 1.7.2 Non-finalized research 1.7.2 Author contributions 2 Manuscript I: Genetic and morphological diatom composition in surface sediments from glacial and thermokarst lakes in the Siberian Arctic 2.1 Abstract 2.2 Introduction 2.3 Materials and methods 2.3.1 Sampling and collection of environmental data 2.3.2 Diatom genetic assessment 2.3.3 Raw sequence processing and taxonomic assignment 2.3.4 Morphological diatom identification 2.3.5 Statistical analyses 2.4 Results 2.4.1 Genetic-based diatom composition, diversityand diatom-environment relationship 2.4.2 Morphological-based diatom composition, diversity and diatom-environment relationship 2.4.3 Comparison of spatial diatom patterns obtained from the genetic and morphological approaches 2.5 Discussion 2.5.1 Genetic and morphological diatom composition and diversity 2.5.2 Diatom composition is affected by lake type and lake water parameters 2.6 Conclusions 2.7 Acknowledgments 3 Manuscript II: Plant sedimentary ancient DNA from Far East Russia covering the last 28 ka reveals different assembly rules in cold and warm climates 3.1 Abstract 3.2 Introduction 3.3 Methods 3.3.1 Study area 3.3.2 Sampling and dating 3.3.3 Genetic laboratory works 3.3.4 Processing the sequence data 3.3.5 Statistical analyses 3.4 Results 3.4.1 Overview of the sequencing data and taxonomic composition 3.4.2 Taxonomic alpha and beta diversity 3.4.3 Phylogenetic alpha and beta diversity 3.4.4 Relationship between taxonomic composition and phylogenetic diversity 3.5 Discussion 3.5.1 Vegetation history revealed by sedaDNA 3.5.2 Patterns oftaxonomic alpha diversity and their relationship to community composition 3.5.3 Relationship between richness and phylogenetic alpha and beta diversity 4 Manuscript III: Sedimentary DNA identifies modem and past macrophyte diversity and its environmental drivers in high latitude and altitude lakes in Siberia and China 4.1 Abstract 4.2 Introduction 4.3 Materialsand Methods 4.3.1 Field sampling of surface and core samples 4.3.2 Environmental data 4.3.3 Molecular genetic laboratory work 4.3.4 Bioinformatic analyses 4.3.5 Statistical analyses 4.4 Results 4.4.1 Macrophyte diversity in surface sediments inferred from sedDNA 4.4.2 Relationship of modem macrophyte richness and environmental variables 4.4.3 The relationship between modem macrophyte community and environmental variables 4.4.4 Past macrophyte richness and composition inferred from sedaDNA 4.4.5 Past macrophyte compositional changes and its environmental drivers 4.5 Discussion 4.5.1 Retrieval of aquatic plant diversity using the tmL P6 loop plant DNA metabarcode 4.5.2 Modem macrophyte diversity and its relation to environmental factors 4.5.3 Temporal macrophyte diversity as an indicator for past environmental change 4.6 Conclusion 5 Synopsis 5.1 Potential and limitations of sedimentary DNA in the applied study 5.1.1 Sedimentary DNA is a powerful proxy 5.1.2 Limitations in sedimentary DNA 5.2 Spatial patterns of vegetation, macrophytes and diatoms 5.2.1 Composition and diversity of vegetation 5.2.2 Composition and diversity of macrophytes 5.2.3 Composition and diversity of diatoms 5.3 Temporal patterns of vegetation, macrophytes and diatoms 5.3.1 Composition and diversity of vegetation 5.3.2 Composition and diversity of macrophytes 5.3.3 Composition and diversity of diatoms 5.4 Outlooks and conclusions Appendices Appendix 1 for Manuscript I Appendix 2 for Manuscript II Appendix 3 for Manuscript III References
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