Nutrient availability and limitation within soils of polygonal tundra in the Sakha Republic, Russian Federation Dissertation zur Erlangung des Doktorgrades an der Fakult¨atf¨urMathematik, Informatik und Naturwissenschaften, Fachbereich Geowissenschaften der Universit¨atHamburg vorgelegt von Fabian Beermann aus Hamburg Hamburg 2016 Tag der Disputation: 11.01.2016 Folgende Gutachter empfehlen die Annahme der Dissertation: Prof. Dr. Lars Kutzbach Prof. Dr. Eva-Maria Pfeiffer Table of Contents Table of Contents Table of Contents III List of Figures VI List of Tables VIII List of Symbols and Abbreviations IX Summary XIII Zusammenfassung XVII 1 Introduction 1 1.1 Introduction and Objectives . .1 1.2 Chapter Overview . .5 1.3 Authors’ Contribution . .6 2 Nutrient Availability in Arctic Peatlands 9 2.1 Arctic Peatlands in the Climate System . .9 2.1.1 Arctic Peatlands and their Carbon Balance . .9 2.1.2 Permafrost Soils . 10 2.1.3 Arctic Peatlands in a Changing Climate . 11 2.2 Nutrient Availability in Arctic Peatlands . 13 2.2.1 Nitrogen . 13 2.2.2 Phosphorus . 15 3 Material and Methods 17 3.1 Fieldwork . 17 3.1.1 Active Layer Studies . 17 3.1.2 Permafrost Studies . 18 3.1.3 Vegetation Sampling . 19 3.1.4 Monitoring Soil Thermal and Hydrological Conditions . 20 3.2 Laboratory Work . 21 3.2.1 Nutrient Analyses . 21 3.2.2 Microbial Biomass Analyses . 22 III Table of Contents 3.2.3 Soil-Physical Analyses . 22 3.2.4 Incubation of Soil Samples . 23 3.3 Statistical Analyses . 23 3.3.1 Nutrient Stoichiometry . 23 3.3.2 Elemental pools . 24 3.3.3 Incubation experiment . 24 3.4 Modeling Active Layer Thickness . 25 4 Geographical Characterization of the Study Areas in the Sakha Republic 27 4.1 The Sakha Republic . 27 4.2 Lena River Delta - Samoylov Island . 27 4.2.1 Study Area in the Lena River Delta . 27 4.2.2 Soils and Vegetation on Samoylov Island . 29 4.3 Indigirka Lowlands - Kytalyk . 32 4.3.1 Polygonal Tundra in the Indigirka Lowlands . 32 4.3.2 Soils in the Indigirka Lowlands . 34 4.3.3 Vegetation in the Indigirka Lowlands . 39 4.4 Kolyma River Delta - Pokhodsk . 39 4.4.1 Study Area in the Kolyma River Delta . 39 4.4.2 Soils and Vegetation in the Kolyma River Delta . 41 5 Stoichiometric Analysis of Nutrient Availability (N, P, K) within the Polygonal Tundra 47 5.1 Introduction . 47 5.2 Results . 49 5.2.1 Soil Profiles and Plant Communities . 49 5.2.2 Soil Chemistry and Nutrient Limitation . 51 5.3 Discussion . 56 6 Nitrogen Pools and Permafrost Thaw in Soils of Polygonal Tundra in Eastern Siberia 63 6.1 Introduction . 63 6.2 Results . 65 6.2.1 Cryolithology . 65 6.2.2 Soil Chemistry . 65 6.2.3 Soil Thermal and Hydrological Dynamics . 68 IV Table of Contents 6.2.4 Active Layer Thickness Evolution . 69 6.3 Discussion . 72 6.3.1 Nitrogen Pools . 72 6.3.2 Active Layer Thickness Evolution . 74 6.3.3 Nitrogen Fluxes and Release . 74 7 Effects of Different Temperatures on Soil Microbial Biomass, Microbial Res- piration and Nutrient Availability 77 7.1 Introduction . 77 7.2 Results . 78 7.2.1 Soil Chemistry . 78 7.2.2 Gas Production Measurements . 81 7.3 Discussion . 83 8 Synthesis and Conclusions 89 References 99 Acknowledgements 123 Appendix 125 V List of Figures List of Figures 1.1 Main components of the terrestrial cycles of nitrogen and phosphorus . .3 2.1 Photographs of polygonal tundra and an ice-wedge . 11 2.2 Climate feedback mechanisms in arctic ecosystems . 12 2.3 Overview on the main annual fluxes of nitrogen in arctic soils . 15 2.4 Changes in soil phosphorus availability over time . 16 3.1 Microtopography of the polygon Lhc11, Indigirka Lowlands . 17 3.2 Location and profile of the soil profile IND-3.4 . 19 4.1 Map of the circumpolar permafrost extent including the locations of the three study areas . 28 4.2 Climate diagram from the city Tiksi, near to the Lena River Delta . 29 4.3 Soil profiles in the study area in the Lena River Delta . 30 4.4 Climate diagram for the city Chokurdakh, Indigirka Lowlands . 32 4.5 Polygonal tundra in the Indigirka Lowlands . 33 4.6 Aerial image of the study area in the Indigirka Lowlands . 34 4.7 Soil profiles in the study area in Kytalyk, Indigirka Lowlands . 36 4.8 Climate diagram for the city Chersky, Kolyma River Delta . 40 4.9 Aerial image of the study area in Pokhodsk, Kolyma River Delta . 41 4.10 Soil profiles in the Kolyma River Delta . 43 5.1 Investigated transects in the polygon Lhc11 in the Indigirka Lowlands . 50 5.2 Vegetation communities in the polygon Lhc11 . 51 5.3 Elemental stoichiometry of the plant communities in the polygon Lhc11 . 53 5.4 Amount of nutrients (C, N, P, K) in different compartments of the trophic web (Lhc11) . 54 5.5 Relationship between total carbon and the microbial biomass (Lhc11) . 56 5.6 Elemental stoichiometry in different compartments of the trophic web (Lhc11) . 57 5.7 Relationships between inorganic phosphorus and the microbial biomass (Lhc11) . 58 VI List of Figures 6.1 Pools of carbon, nitrogen ammonium and nitrate in soil cores from Eastern Siberia . 66 6.2 Modeled active layer thickness evolution for soils in Eastern Siberia . 70 7.1 Contents of Cmic and Nmic in the control samples and the incubated sam- ples of the soil profile IND-3.4 . 80 7.2 Contents of DOC and DON in the control samples and the incubated sam- ples, IND-3.4 . 81 7.3 Contents of ammonium in the control samples and the incubated samples, IND-3.4 . 82 7.4 Cumulative release of CO2 and CH4 during the incubation of soil material of the three soil horizons, IND-3.4 . 83 8.1 Nutrient availability and limitation in the soil vegetation system of arctic soils - Synthesis of the main results . 96 A.1 Cryolithological data of the soil cores LEN-1-R, LEN-1-C, and IND-R . 125 A.2 Cryolithological data of the soil cores KOL-1-R, KOL-1-C, KOL-3-R and KOL-3-C . 126 A.3 Cryolithological data of the soil cores KOL-4-R, KOL-4-C, KOL-5 and KOL7.................................... 127 A.4 Pools of carbon, nitrogen, ammonium and nitrate in eleven soil cores from the three study areas . 128 A.5 Monitoring of soil temperatures and soil moisture of different soils in the three study areas . 129 VII List of Tables List of Tables 4.1 Properties of soils from the Lena River Delta . 31 4.2 Properties of different soils from the Indigirka Lowlands . 38 4.3 Plant-communities in the study area in the Indigirka Lowlands . 39 4.4 Properties of soils from the Kolyma River Delta . 45 5.1 Chemical properties in the polygon Lhc11 in the Indigirka Lowlands . 52 5.2 Percentages of the total contents of carbon, nitrogen, phosphorus and potassium that were found in the biologically active fractions (dissolved inorganic, dissolved organic and microbial) - Lhc11 . 55 6.1 Average volumetric contents of inorganic N compounds, total C and total N in the active layer and the perennially frozen ground . 68 6.2 Modeled increase of active layer thickness in the three study areas until 2100 and estimated N-release rates . 71 7.1 Chemical and physical properties of the three different soil horizons of the soil profile IND-3.4 . 79 7.2 Daily volumetric production rates of CO2 and CH4 under the two temper- ature treatments, IND-3.4 . 82 7.3 Percentages of TC which was respired as CO2 and CH4, IND-3.4 . 84 A.1 Comparison of the soils in the studied polygon (LHC) and the surrounding study area (KYT) in the Indigirka Lowlands . 130 A.2 Input data of the active layer thickness model . 131 A.3 Effects of incubation at 5 °C and 15 °C on the elemental composition of samples of three horizons from the soil profile IND-3.4 in the Indigirka Lowlands . 133 VIII List of Symbols and Abbreviations List of Symbols and Abbreviations ALT Active Layer Thickness ANOVA Analyses of Variances a.s.l. above sea level b.s. below surface C Carbon CaCl2 Calcium Chloride CCSM Community Climate System Model CEC Cation Exchange Capacity CH4 Methane Clabile Labile Inorganic Carbon Cmic Microbial Carbon CO2 Carbon Dioxide Cres Residual Carbon D Difference DIN Dissolved Inorganic Nitrogen DOC Dissolved Organic Carbon DOM Dissolved Organic Matter DON Dissolved Organic Nitrogen DOP Dissolved Organic Phosphorus EC Electrical Conductivity Gt Gigaton IX List of Symbols and Abbreviations h hour H2CO3 Carbonic Acid H2SO4 Sulphuric Acid M Molar N Nitrogen N2 Elemental Nitrogen N2O Nitrous Oxide NH3 Ammonia + NH4 Ammonium (NH4)2S2O8 Ammonium Persulfate Nlabile Labile Inorganic Nitrogen Nmic Microbial Nitrogen NO Nitric Oxide − NO2 Nitrite − NO3 Nitrate Nres Residual Nitrogen K2SO4 Potassium Sulfate Klabile Labile Inorganic Potassium Kres Residual Potassium pH pH-value Pg Petagram Plabile Labile Inorganic Phosphorus X List of Symbols and Abbreviations Pmic Microbial Phosphorus 3− PO4 Phosphate Pres Residual Phosphorus RCP Representative Concentration Pathway S Siemens SOM Soil Organic Matter TC Total Carbon TN Total Nitrogen TOC Total Organic Carbon TON Total Organic Nitrogen TWINSPAN Two Way Indicator Species Analyses Vol.% Volumetric Percentages W Watt yr B.P. Years Before Present XI Summary Summary Arctic tundra ecosystems are characterized by short summers, low temperatures and low nutrient availability. Cold and long winters result in soils that are perennially frozen in their lower layers and seasonally frozen in their upper layers.