TREE RINGS AND CLIMATE IN THE GREAT LAKES REGION—PAST, PRESENT, AND FUTURE By Scott Matthew Warner A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of Plant Biology – Doctor of Philosophy Ecology, Evolution, and Behavior Program – Dual Major 2021 ABSTRACT TREE RINGS AND CLIMATE IN THE GREAT LAKES REGION—PAST, PRESENT, AND FUTURE By Scott Matthew Warner As climate change unfolds it is necessary to gain a better understanding of how tree growth is affected by contemporary climate. This can provide information about both prerecorded climate and future growth responses to climate change. Yet, tree growth and its relationship with climate remains understudied in one section of the northeastern United States, the Great Lakes Region. Here, I use dendrochronology to (1) reconstruct 500 years of moisture conditions on South Manitou Island, Lake Michigan, (2) compare growth and growth- climate relationships within/among nine species along a latitudinal gradient from southern Indiana to Upper Michigan, and (3) forecast future growth under climate change. I find that (1) while drought was a regular occurrence since the mid-1500s, the most severe droughts and the most variable conditions overall occurred in the 20th century, (2) the predominant climatic factors associated with growth in the region are summer temperature (negative relationships) and summer precipitation (positive relationships), and that the influence of these factors was strongest in the south, and (3) future growth was projected to decline over the rest of this century as climate change proceeds, independent of latitude. For Nola, beside me throughout iii ACKNOWLEDGMENTS I thank Frank Telewski, for his advice, support, and patience, and for being an excellent major advisor in general. Andrew M. Jarosz went far beyond the role of a typical guidance committee member providing ample amounts of support, feedback, and ideas. In particular, I thank Dr. Jarosz for helping to conceive the study that comprises Chapter 3. I am also grateful to my other committee members, Jeffrey Andresen and Steve Chhin for their guidance. Specifically, thanks to Dr. Andresen for his advice on modeling and selecting climate projections. Thanks to Dr. Chhin for advice on statistics and dendrochronological methods. Alan Arbogast, Justin Maxwell, and William Lovis also provided substantial advice. Many other persons also provided advice, too many to list. Many persons provided help in the lab and field, particularly Opal Jain. Thanks also to Alan Arbogast, Jill Grimes, Andrew Jarosz, William Lovis, Jaime Salisbury, Andrew Warner, and Nola Warner for help in the field. Thanks to Hazel Anderson, Gillian Chirillo, Matthew Hadden, and Samantha Jeffries for help in the lab. For help in the field and lab, thanks to Ross Chinavare, Garrett Mullanix, Hunter Salisbury, and Frank Telewski. Thank you to the landowners/stewards who generously allowed me to sample on their land: The Huron Mountain Club, the Indiana Audubon Society, the Jacobson Family (Tustin, MI), Kalamazoo Nature Center, the Michigan Audubon Society, the Michigan Department of Natural Resources, the National Parks Service (NPS Permit No. 85839), the Peterson Family (Stonington Peninsula, MI), Saginaw County Parks, the United States Forest Service, and the University of Michigan Biological Station. iv Several funding agencies provided support. Thank you to the Plant Science Fellowship (Michigan State University [MSU]), the Alfred H. and Jean Goldner Endowment, W.J. Beal Botanical Garden (MSU), the Huron Mountain Wildlife Foundation, the James E. Rodman Endowment, the UAW Cal Rapson Endowment, donors to the William A. Lovis Endowment for Environmental Archaeology, the Department of Geography, Environment and Spatial Sciences (MSU), the Department of Plant Biology (MSU), the Ecology, Evolution, and Behavior Program (MSU), the Paul A. Taylor Endowment, and the Dissertation Completion Fellowship (MSU). For funded internships, thank you to the MSU Herbarium (MSC) and the Natural Science Collections Internship (MSU). To Justin Maxwell, I am grateful for providing data for A. saccharum, C. ovata, L. tulipifera, Q. alba, and Q. rubra at Pioneer Mothers Memorial Forest. To Alex Dye, I am grateful for providing data for T. canadensis at Huron Mountain Club. Thank you to Edward Cook for providing an unpublished T. occidentalis chronology from South Manitou Island. For hospitality, thank you to the rangers of South Manitou Island, Carl Wilms of Mary Gray Bird Sanctuary, the Kalamazoo Nature Center, and the Huron Mountain Wildlife Foundation. Thank you to Inter-Research for permitting me to reprint with slight formatting modifications a paper from Climate Research which comprises chapter 2 of this document: S.M. Warner, S.J. Jeffries, W.A. Lovis, A.F. Arbogast, & F.W. Telewski. 2021. Tree ring-reconstructed late summer moisture conditions, 1546 to present, northern Lake Michigan, USA. Climate Research. 83:43–56. https://doi.org/10.3354/cr01637. © Inter-Research 2021. Resale or republication not permitted without written consent of the publisher. v Thank you to those who most inspired me in my undergraduate program, Todd Barkman and Steve Keto. To Ralph Reitz, thanks for being the first person to teach me about botany. I am thankful to my immediate, original, and in-law family members, particularly my wife, parents, and children for their support. vi TABLE OF CONTENTS LIST OF TABLES...............................................................................................................................ix LIST OF FIGURES..............................................................................................................................x CHAPTER ONE.................................................................................................................................1 INTRODUCTION...............................................................................................................................1 Prehistoric, Historic, and Future Climate Change...............................................................1 Plant Responses to Climate Change....................................................................................2 Forests and Climate of the Great Lakes Region..................................................................9 Study Objectives...............................................................................................................11 APPENDIX..........................................................................................................................12 CHAPTER TWO..............................................................................................................................14 TREE-RING-RECONSTRUCTED LATE-SUMMER MOISTURE CONDITIONS, 1546 TO PRESENT, SOUTH MANITOU ISLAND, LAKE MICHIGAN, USA….....................................................................14 Acknowledgments………………………………………………………………………………………………………..15 Abstract.............................................................................................................................15 Introduction......................................................................................................................17 Methods............................................................................................................................21 Results...............................................................................................................................25 Discussion.........................................................................................................................30 Conclusion.........................................................................................................................36 APPENDIX..........................................................................................................................38 CHAPTER THREE............................................................................................................................47 IN GREAT LAKES REGION MESIC FORESTS, CONTEMPORARY GROWTH-CLIMATE RELATIONSHIPS SUGGEST THAT SOUTHERLY TREE POPULATIONS ARE MOST VULNERABLE TO CLIMATE CHANGE.............................................................................................47 Abstract.............................................................................................................................47 Introduction......................................................................................................................48 Methods............................................................................................................................51 The Study Region..................................................................................................51 The Study Species.................................................................................................52 Field Methods.......................................................................................................52 Core Processing, Cross-Dating, and Detrending...................................................53 Quantifying and Comparing Growth-Climate Relationships.................................55 Results...............................................................................................................................58 General Chronology Characteristics......................................................................58 Comparing Tree-Ring