Using Phytolith Analysis to Discern Holocene Vegetation Change on Sanak Island, Western Gulf of Alaska Cricket C
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Antioch University AURA - Antioch University Repository and Archive Student & Alumni Scholarship, including Dissertations & Theses Dissertations & Theses 2013 A History of Place: Using Phytolith Analysis to Discern Holocene Vegetation Change on Sanak Island, Western Gulf of Alaska Cricket C. Wilbur Antioch University - New England Follow this and additional works at: http://aura.antioch.edu/etds Part of the Botany Commons, Climate Commons, Geology Commons, Indigenous Studies Commons, Natural Resources and Conservation Commons, Paleobiology Commons, Paleontology Commons, Plant Biology Commons, and the Terrestrial and Aquatic Ecology Commons Recommended Citation Wilbur, Cricket C., "A History of Place: Using Phytolith Analysis to Discern Holocene Vegetation Change on Sanak Island, Western Gulf of Alaska" (2013). Dissertations & Theses. 89. http://aura.antioch.edu/etds/89 This Dissertation is brought to you for free and open access by the Student & Alumni Scholarship, including Dissertations & Theses at AURA - Antioch University Repository and Archive. It has been accepted for inclusion in Dissertations & Theses by an authorized administrator of AURA - Antioch University Repository and Archive. For more information, please contact [email protected], [email protected]. Department of Environmental Studies DISSERTATION COMMITTEE PAGE The undersigned have examined the dissertation entitled: A History of Place: Using Phytolith Analysis to Discern Holocene Vegetation Change on Sanak Island, Western Gulf of Alaska presented by Cricket C Wilbur, candidate for the degree of Doctor of Philosophy and hereby certify that it is accepted*. Committee Chair: James W. Jordan, Ph.D., Department of Environmental Studies, Antioch University New England, Keene, NH. Committee Member: Charles G. Curtin, Ph.D., Department of Environmental Studies, Antioch University New England, Keene, NH. Committee Member: Deborah M. Pearsall, Ph.D., Department of Anthropology, University of Missouri, Columbia, MO. Defense Date: June 13, 2013 Date Submitted to the Registrar’s Office: *Signatures are on file with the Registrar’s Office, Antioch University New England. A History of Place: Using Phytolith Analysis to Discern Holocene Vegetation Change on Sanak Island, Western Gulf of Alaska by Cricket C. Wilbur A dissertation submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY In Environmental Studies at Antioch University New England 2013 Copyright 2014 Cricket C. Wilbur All rights reserved i ACKNOWLEDGEMENTS The community of support I very graciously received from my committee, faculty, staff, fellow classmates, colleagues and friends, co-workers and especially my family made this project possible. My thesis advisor, James Jordan, gave me a wonderful opportunity to be part of his research program in Southwest Alaska. I would like to thank Jim and the rest of my thesis committee, Deborah Pearsall and Charles Curtin for their guidance throughout the research and writing of this thesis. In addition this project would not have been possible without the support of the many people who provided me samples from Sanak Island and who assisted me with sample processing. Bruce Finney shared his Sanak Peak Lake sediment core and Nancy Huntly her Sanak Island plant samples. Sandstone Archaeology and the PaleoResearch Institute processed the sediment samples for fossil phytoliths. The Antioch University New England (AUNE) Herbarium provided plant materials and, equipment and supplies for this project. It was a privilege to be a student in the Environmental Studies Department at AUNE. The faculty and staff were very helpful and supportive. I’d like to thank my classmates who made this a wonderful experience. I am also grateful to my cohort for their friendship and interesting conversations. Finally, I would like to thank my family Dean, Kelly and Sam, and my parents for their enduring support, encouragement, and patience throughout this project. Financial support for this project was provided in part by NSF Grant 0508101 BE/CNH: Complex Ecosystem Interactions over Multiple Spatial and Temporal Scales: ii The Biocomplexity of Sanak Island to Principle Investigator Herbert Maschner at Idaho Sate University, and an AUNE Environmental Studies Department Professional Development Grant (2013). iii ABSTRACT This study investigated a terrestrial climate proxy, phytoliths, as a complimentary approach to documenting the dynamics of present and past vegetation on Sanak Island, the largest island in a small island group in the eastern Aleutian archipelago, and as a new basis by which to interpret Holocene environmental variability in Alaska. A phytolith reference collection was established from 59 selected plant species of maritime tundra belonging to 27 families. The grass species and a sedge species produced abundant phytolith forms whereas the majority of dicotyledons in this study were trace producers of phytoliths. A paleoenvironmental reconstruction from fossil phytoliths recovered from a continuous lake sediment core indicates that sedges and cool season grasses were present on this landscape throughout most of the Holocene suggesting the long-term dominance of maritime climate on island vegetation. Adaptation and resilience of the modern vegetation on Sanak Island to a warming climate is suggested by the densities of silicified stomata recovered from six species of grasses, one species of fern, and one species of horsetail when compared to the paleoenvironmental reconstruction. The changes in stomata frequency in the plants on Sanak Island today may have connections to future changes in regional and global climate through the water cycle. Our changing climate is forcing ecosystems to migrate, acclimate or go extinct demonstrating that new insights into ecosystem responses to present and past environmental variation, and forecasting future ecological change are especially relevant today for ecologic and economic sustainability. The electronic version of this Dissertation is at OhioLink EDT Center, www.ohiolink.edu/etd. iv TABLE OF CONTENTS ACKNOWLEDGEMENTS i ABSTRACT iii LIST OF FIGURES AND TABLES vi CHAPTER 1: Introduction 1 Introduction Research Goals & Objectives Conclusions References CHAPTER 2: Phytolith Assemblages in Tundra Plants from Sanak Island, 15 Western Gulf of Alaska Abstract Introduction Setting Methods Results Discussion Conclusions References CHAPTER 3: A Lacustrine Phytolith Record from Western Alaska as 49 a Proxy for Climate Variability during the Holocene Abstract Introduction Study Site Methods Results Discussion Conclusions References v CHAPTER 4: Silicified Stomata Complexes in Maritime Tundra Plants 79 from Sanak Island, Western Gulf of Alaska suggest response to changes in Atmospheric CO2 Concentrations Abstract Introduction Setting Methods Results Discussion Conclusions References CHAPTER 5: Conclusions 104 Summary References APPENDIX Copyright Permissions 108 vi LIST OF FIGURES AND TABLES LIST OF FIGURES CHAPTER 1 Figure 1. Map of the Sanak Islands, Alaska. 13 Figure 2. Map of the Arctic Region. 14 CHAPTER 2 Figure 1. Map of the Sanak Islands, Alaska. 41 Figure 2. Transmitted light photomicrographs of phytoliths from modern 42 plants on Sanak Island, AK. Figure 3. Frequency of phytolith morphotypes in grass species from the 46 Aveneae, Festuceae, and Hordeum/Triticeae tribes on Sanak Island, AK. CHAPTER 3 Figure 1. Map of the Sanak Islands, Alaska. 74 Figure 2. Pollen diagram of Sanak and Deep Lakes, Sanak Island, AK. 75 Figure 3. Distribution of phytolith morphotypes from a sediment core of 76 Sanak Peak Lake, Sanak Island, AK. Figure 4. Calculated sedimentation rates of phytolith zones. 77 CHAPTER 4 Figure 1. Map of the Sanak Islands, Alaska. 96 Figure 2. Transmitted light photomicrographs of silicified stomata from 97 plant species examined in this study. Figure 3. Length versus width of silicified stomata from non-grass and 98 grass species examined in this study. Figure 4. Silicified stomata densities of selected tundra plants examined 102 in this study. vii LIST OF TABLES CHAPTER 2 Table 1. List of maritime tundra plant species examined in this study. 47 Table 2. Abundances of grass phytoliths in plant species examined in 48 this study. CHAPTER 3 Table 1. Fossil phytolith morphologies recovered from a Sanak Peak 78 Lake sediment core, Sanak Island, AK. CHAPTER 4. Table 1. Silicified stomata traits from selected plant species on 103 Sanak Island, AK. 1 Chapter 1 Introduction “Where the telescope ends, the microscope begins. Which of the two has the grandeur view?” ------ Victor Hugo Introduction Evidence for climate change can be found from the upper reaches of the atmosphere to the bottom of the oceans. These data point to a warming planet especially at higher latitudes where temperatures are rising more quickly. Ecosystems in northern high latitudes play a critical role in the Earth System because they represent over 22% of its surface area, are sensitive to subtle changes in climate, and are tightly linked with the atmosphere (Chapin et al. 2000). As the planet warms Arctic ecosystems in particular are experiencing profound environmental changes due to their relationship with the climate system. Less well understood, however, is how the variations of individual components of the climate system affect Arctic landscapes and vegetation. This study examines an Arctic ecosystem, Sanak Island in the western Gulf of Alaska (Figure 1) through the lens of the paleo-proxy phytoliths, comparing present and past