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kobvindex_GFZ1882058135
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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.
Note:
Dissertation, Universität Potsdam, 2024
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Table of contents
ABSTRACT
ZUSAMMENFASSUNG
ABBREVIATIONS AND NOMENCLATURE
CHAPTER 1: INTRODUCTION
1.1 SCIENTIFIC BACKGROUND
1.1.1 ARCTIC GROUND
1.1.2 THE PHENOMENON OF PERMAFROST
1.1.3 ARCTIC NON - PERMAFROST AREAS
1.1.4 HYPOTHESIS
1.2 AIMS AND OBJECTIVES
1.3 METHODS
1.3.1 FIELD METHODS AND SAMPLING APPROACH
1.3.2 STUDY AREA SELECTION
1.3.3 LABORATORY METHODS
1.4 THESIS ORGANISATION
CHAPTER 2: LARGE HERBIVORES ON PERMAFROST – A PILOT STUDY OF GRAZING IMPACTS ON PERMAFROST SOIL CARBON STORAGE IN NORTHEASTERN SIBERIA
2.1 ABSTRACT
2.2 I NTRODUCTION
2.3 STUDY AREA
2.4 METHODS
2.4.1 FIELD SAMPLING APPROACH
2.4.2 LABORATORY WORK
2.4.3 DATA ANALYSIS AND EXTERNAL DATA
2.5 RESULTS
2.5.1 VEGETATION ASSESSMENT
2.5.2 SEASONAL THAW DEPTH
2.5.3 CARBON PARAMETERS (TOC, TOC/TN RATIOS , AND Δ13 C RATIOS )
2.5.4 GRAIN SIZE DISTRIBUTION AND WATER CONTENT
2.5.5 STATISTICS AND CORRELATION ANALYSIS
2.6 DISCUSSION
2.6.1 EFFECTS OF GRAZING ON VEGETATION STRUCTURE AND PERMAFROST THAW
2.6.2 CARBON ACCUMULATION UNDER GRAZING IMPACT
2.6.3 METHODOLOGICAL LIMITATIONS OF THE PILOT STUDY
2.7 CONCLUSION
2.8 DATA AVAILABILITY STATEMENT
2.9 AUTHOR CONTRIBUTIONS
2.10 FUNDING
2.11 ACKNOWLEDGEMENTS
2.12 CONFLICT OF INTERESTS
CHAPTER 3: IMPACTS OF REINDEER ON SOIL CARBON STORAGE IN THE SEASONALLY FROZEN GROUND OF NORTHERN FINLAND: A PILOT STUDY
3.1 ABSTRACT
3.2 I NTRODUCTION
3.3 STUDY AREA
3.4 METHODS
3.4.1 FIELD WORK
3.4.2 LABORATORY ANALYSIS
3.4.3 DATA ANALYSIS AND CALCULATIONS
3.5 RESULTS
3.5.1 CORE DESCRIPTIONS
3.5.2 VEGETATION
3.5.3 CARBON PARAMETERS
3.5.6 COMPARATIVE DATA ANALYSIS
3.6 DISCUSSION
3.6.1 REINDEER IMPACT ON SOIL CARBON STORAGE
3.6.2 REINDEER IMPACT ON VEGETATION
3.6.3 REINDEER IMPACT ON GROUND CHARACTERISTICS
3.6.4 SOC DENSITY AND STOCKS ACROSS THE KUTUHARJU STATION AREA
3.6.5 METHODOLOGICAL LIMITATIONS OF THE PILOT STUDY DESIGN
3.6.6 IMPLICATIONS OF THE PILOT STUDY FOR FUTURE RESEARCH
3.7 CONCLUSION
3.8 DATA AVAILABILITY
3.9 AUTHOR CONTRIBUTION
3.10 COMPETING INTERESTS
3.11 ACKNOWLEDGEMENTS
3.12 FUNDING
TABLE 3-1
TABLE 3-2
TABLE 3-3
CHAPTER 4: LIPID BIOMARKER SCREENING TO TRACE RECENT LARGE HERBIVORE INFLUENCE ON SOIL CARBON IN PERMAFROST AND SEASONALLY FROZEN ARCTIC GROUND
4.1 ABSTRACT
4.2 I NTRODUCTION
4.3 STUDY AREA
4.4 METHODS
4.4.1 SAMPLING APPROACH
4.4.2 LABORATORY ANALYSIS
4.4.3 LIPID BIOMARKER INDICES
4.4.4 STATISTICS
4.5 RESULTS
4.5.1 TOC
4.5.2 C/N RATIO
4.5.3 STABLE CARBON ISOTOPE RATIO
4.5.4 ABSOLUTE N- ALKANE CONCENTRATION
4.5.5 AVERAGE CHAIN LENGTH
4.5.6 CARBON PREFERENCE INDEX
4.5.7 HIGHER - PLANT ALCOHOL INDEX
4.5.8 STATISTICAL RESULTS
4.6 DISCUSSION
4.6.1 EFFECTS OF GRAZING INTENSITY ON BIOMARKER SIGNALS
4.6.2 EFFECTS OF GROUND THERMAL REGIME ON SOIL OM DEGRADATION
4.6.3 I MPACT OF HERBIVORY ON PERMAFROST OM STORAGE
4.7 CONCLUSION
4.8 ACKNOWLEDGEMENTS
4.9 COMPETING INTERESTS
4.10 AUTHOR CONTRIBUTION
4.11 FUNDING
4.12 DATA AVAILABILITY
CHAPTER 5: SYNTHESIS
5.1 ECOSYSTEM CHANGES UNDER THE IMPACT OF LARGE HERBIVORES
5.2 GRAZING EFFECTS ON SOIL ORGANIC MATTER DECOMPOSITION
5.3 F EASIBILITY OF UTILISING HERBIVORY IN THE ARCTIC
5.4 RESEARCH IMPLICATIONS FOR SUCCESSFUL PLANNING AND USE OF ARCTIC HERBIVORY
REFERENCES 93
FINANCIAL AND TECHNICAL SUPPORT
APPENDIX 1
APPENDIX I ORGANIC CARBON CHARACTERISTICS IN ICE - RICH PERMAFROST IN ALAS AND YEDOMA DEPOSITS , CENTRAL YAKUTIA, SIBERIA
APPENDIX II WHAT ARE THE EFFECTS OF HERBIVORE DIVERSITY ON TUNDRA ECOSYSTEMS ? A SYSTEMATIC REVIEW (ABSTRACT)
APPENDIX III SUPPLEMENTARY MATERIAL TO CHAPTER 2: LARGE HERBIVORES ON PERMAFROST – A PILOT STUDY OF GRAZING IMPACTS ON PERMAFROST SOIL CARBON STORAGE IN NORTHEASTERN SIBERIA
APPENDIX IV SUPPLEMENTARY MATERIAL TO CHAPTER 3: IMPACTS OF REINDEER ON SOIL CARBON STORAGE IN THE SEASONALLY FROZEN GROUND OF NORTHERN FINLAND : A PILOT STUDY
APPENDIX V SUPPLEMENTARY MATERIAL TO CHAPTER 4: A PILOT STUDY OF LIPID BIOMARKERS TO TRACE RECENT LARGE HERBIVORE INFLUENCE ON SOIL CARBON IN PERMAFROST AND SEASONALLY ROZEN ARCTIC GROUND
APPENDIX VI SUPPLEMENTARY MATERIAL TO APPENDIX IV: ORGANIC CARBON CHARACTERISTICS IN ICE - RICH PERMAFROST IN ALAS AND YEDOMA DEPOSITS , CENTRAL YAKUTIA, SIBERIA
ACKNOWLEDGEMENTS - DANKSAGUNG
Language:
English
Keywords:
Hochschulschrift
DOI:
10.25932/publishup-62424
URL:
https://doi.org/10.25932/publishup-62424
Author information:
Große, Guido 1976-
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