Paleoecological and Carbon Accumulation Dynamics of a Fen Peatland in the Hudson Bay Lowlands, Northern Ontario, from the Mid-Holocene to Present

Paleoecological and Carbon Accumulation Dynamics of a Fen Peatland in the Hudson Bay Lowlands, Northern Ontario, from the Mid-Holocene to Present by Benjamin Cody O’Reilly A thesis submitted in conformity with the requirements for the degree of Master of Science Department of Geography University of Toronto © Copyright by Benjamin Cody O’Reilly 2011 Paleoecological and Carbon Accumulation Dynamics of a Fen Peatland in the Hudson Bay Lowlands, Northern Ontario, from the Mid-Holocene to Present Benjamin O’Reilly Master of Science Department of Geography University of Toronto 2011 Abstract Pollen assemblages, peat humification and carbon:nitrogen stratigraphy were examined at high resolution in a core from a fen peatland in the Hudson Bay Lowlands, Northern Ontario, to interpret the factors that drive long-term peatland dynamics. Subtle changes in the vegetation community are evident over the record, suggesting both allogenic and autogenic influences, but a fen community appears to have been resilient to external perturbations including isostatic rebound and hydroclimatic changes between 6400 and 100 years BP. Paleoclimatic reconstructions from the fossil pollen assemblages indicate that precipitation increased 3000 years BP at the end of the Holocene Thermal Maximum, and that carbon accumulation in the fen was controlled more by effective surface moisture (precipitation) than by temperature. The pollen record suggests changes over the past century, including increases in shrub Betula, Alnus, Ambrosia, and Cyperaceae and a decrease in Sphagnum spores, consistent with the observed Pan-Arctic shrub increase. ii Acknowledgments I would like to start by thanking Dr Sarah Finkelstein for the guidance and assistance that she afforded me throughout my Masters. She was constantly keeping me motivated and excited about the next step, and was always so encouraging. I am very grateful for the opportunity that was given to me to work on this project. This project relied substantially on the funding and support of a number of sources. I wish to thank the Ontario Ministry of Natural Resources, the Ontario Ministry of Training, Colleges and Universities, the Natural Sciences and Engineering Research Council of Canada, the Wildlife Conservation Society of Canada and the Northern Scientific Training Program of the Department of Indian Affairs and Northern Development. Once the roads end, the cost of doing field research really takes off, and it couldn’t be done without the generosity of these sources. The logistical support provided by Brian Steinback and the rest of the staff at DeBeers Victor Mine Environmental Lab is greatly appreciated. The stay at Victor was memorable, and I hope my torn pants were a lesson in proper field attire (or at the very least, a lesson in writing a proper near-miss card). I must admit, very few things cap off a day of walking around expansive muskeg like pulling a truck, so thanks for the staff at Victor for making us feel welcome! HMS PGB would never have sailed without the careful construction of Mircea Pilaf. Thank you for all your help over these two years Mircea! I also wish to thank Jim McLaughlin and Benoit Hamel for the core collection and supplemental site description. To the others in the Paleoecology Lab – Carlos, John-Paul, Charlotte, Joan, Maara, Kristen and Nikki and those already moved on – Jane and Jen, thanks for all the coffee breaks, patio beers, rants, discussions, assistance and good times. I owe you all a lot for the motivation iii you afforded me, and for not laughing at my jokes resulting in me thinking of better ones! A special thanks to Kristen for helping sub-sample peat when the temperatures of the sediment lab approached solar-surface levels, and Joan for patiently sharing her vast knowledge of statistics with me. I would also like to thank Charlie and Jock for the visits, interesting conversations and helpful suggestions. I really need to thank my parents twice, mainly because I forgot to thank them in my undergraduate thesis acknowledgements, but more so because they encouraged me to take this opportunity and have been more supportive than I could have ever dreamed. I hope I can repay their kindness and goodwill! To the rest of the folks of PGB, thanks for making movie nights, Fridays, Chinese New Year and other events memorable. It really helped get through the tough parts of graduate school, and I will cherish this time forever. Lastly I’d like to thank my girlfriend Tatiana for all her love and support during this time in my life. Thanks for all your encouragement and motivation, especially when I was at my grumpiest! I still think the Washington Redskins are better than the Philadelphia Eagles though! iv Table of Contents TITLE PAGE………………………………………………………………………………………i ABSTRACT………………………………………………………………………………………ii ACKNOWLEDGEMENTS………………………………………………………………………iii TABLE OF CONTENTS………………………………………………………………………….v LIST OF TABLES………………………………………………………………………………viii LIST OF FIGURES………………………………………………………………………………ix LIST OF APPENDICES………………………………………………………………………….xi CHAPTER 1: INTRODUCTION……………………………………………………...………….1 1.1 GENERAL INTRODUCTION AND OBJECTIVES………………………………...1 1.1.1 Development of Northern Peatlands………………………………………2 1.1.2 Rationale…………………………………………………………………..4 1.1.3 Proxies Utilized and their interpretation…………………………………..5 1.1.4 Ecosystem Resilience…………………...…………………………………9 1.1.5 Peatlands as Complex Adaptive Systems…………………………………9 1.2 LITERATURE REVIEW……………………………………………………………12 1.2.1 Holocene Climatic Transitions…………………………………………...12 1.2.2 Past Paleoecological Studies……………………………………………..13 1.2.3 Carbon Accumulation in Peatlands………………………………………20 1.3 STUDY SITE………………………………………………………………………...23 v 1.3.1 Study Region……………………………………………………………..23 1.3.2 Site Description…………………………………………………………..24 1.3.3 Climate of the study area………………………………………………...25 1.3.4 Local and Regional Geologic Setting……………………………………27 1.3.5 Quaternary Glacial History of the Hudson Bay Lowlands………………27 1.3.6 Post-glacial Isostatic Adjustment………………………………………...29 1.3.7 Local and Regional Vegetation…………………………………………..31 CHAPTER 2: METHODS……………………………………………………………………….34 2.1 FIELD METHODS…………………………………………………………………..34 2.2 LABORATORY METHODS………………………………………………………..35 CHAPTER 3: RESULTS………………………………………………………………………...44 3.1 210Pb DATING OF VICM_T3_SP3………………………………………………….44 3.2 AGE-DEPTH MODEL DEVELOPMENT………………………………………….45 3.3 PALEOECOLOGICAL RECONSTRUCTION…………………………………….49 3.4 BULK DENSITY……………………………………………………………………54 3.5 C:N STRATIGRAPHY……………………………………………………………...54 3.6 LORCA………………………………………………………………………………59 3.7 PEAT HUMIFICATION…………………………………………………………….62 3.8 PALEOCLIMATIC RECONSTRUCTIONS………………………………………..65 CHAPTER 4: DISCUSSION……………………………………………………………………76 vi 4.1 DRIVERS OF VEGETATION CHANGE…………………………………………..76 4.2 CLIMATE RECONSTRUCTION…………………………………………………...83 4.3 CONTROLS ON CARBON ACCUMULATION DYNAMICS……………………89 4.4 RESILIENCE OF THE VICTOR FEN ECOSYSTEM……………………………...92 CHAPTER 5: CONCLUSION…………………………………………………………………..95 5.1 CONCLUSIONS FROM THE VICTOR FEN RECORD..………………………….95 5.2 FUTURE WORK…………………………………………………………………….97 REFERENCES…………………………………………………………………………………..99 APPENDIX A: RAW COUNTS OF VC01…………………………………………………….112 vii List of Tables Table 1: The three study proxies and their interpreted reconstruction…………………………..11 Table 2: Grain counts for the rationale of a 200 arboreal pollen grain count……………………40 Table 3: AMS radiocarbon dates for the Victor Mine Fen Core (VICM_T3_SP3)……………..48 Table 4: Percent carbon and nitrogen data used to test the homogeneity of the peat matrix…….56 viii List of Figures Figure 1: A map of past paleoecological studies in relation to the Victor fen…………………..15 Figure 2: Postglacial emergence curves for the Victor fen site………………………………….31 Figure 3: The activity of 210Pb in the uppermost Victor fen core section………………………..45 Figure 4: Age-depth model derived for the Victor fen Core……………………………………..47 Figure 5: Percentage pollen diagram from Victor fen core……………………………………...52 Figure 6: Pollen Influx diagram for the Victor fen core…………………………………………53 Figure 7: Bulk density of the Victor fen core……………………………………………………54 Figure 8: Percentage carbon in the peat sequence of the Victor fen core………………………..57 Figure 9: Percentage nitrogen in the peat sequence of the Victor fen core……………………...58 Figure 10: Carbon/Nitrogen ratio of the peat sequence of the Victor fen core………………….59 Figure 11: LORCA estimates for the entire peat sequence of the Victor fen core………………60 Figure 12: LORCA estimates for the 60 cm to base section of the Victor fen core……………..61 Figure 13: LORCA estimates for the Victor fen core based on the age-depth model…………...61 Figure 14: Raw spectrophotometric absorbance results for the Victor fen core…………………64 Figure 15: Detrended absorbance values (Ad) for the Victor fen core…………………………...64 Figure 16: Reconstructed Average Annual Air Temperature for the Victor fen core…………...68 Figure 17: Reconstructed Average Annual Air Temperature of the most recent 2000 years for the Victor fen core…………………………………………………………………………………...69 Figure 18: Reconstructed Average July Temperature for the Victor fen core…………………..70 ix Figure 19: Reconstructed Average July Temperature of the most recent 2000 years for the Victor fen core…………………………………………………………………………………………...71 Figure 20: Reconstructed Total Annual Precipitation for the Victor fen core…………………...72 Figure 21: Reconstructed Total Annual Precipitation of the most recent 2000 years for the Victor fen core…………………………………………………………………………………………...73 Figure 22: Reconstructed Total

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