THE SAGEBRUSH STEPPE OF MONTANA AND SOUTHEASTERN IDAHO SHOWS EVIDENCE OF HIGH NATIVE PLANT DIVERSITY, STABILITY, AND RESISTANCE TO THE DETRIMENTAL EFFECTS OF NONNATIVE PLANT SPECIES by Ryan Lane Quire A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Plant Science MONTANA STATE UNIVERSITY Bozeman, Montana April 2013 © COPYRIGHT by Ryan Lane Quire 2013 All Rights Reserved ii APPROVAL of a thesis submitted by Ryan Lane Quire This thesis has been read by each member of the thesis committee and has been found to be satisfactory regarding content, English usage, format, citation, bibliographic style, and consistency, and is ready for submission to The Graduate School. Dr. Matthew Lavin Approved for the Department of Plant Sciences and Plant Pathology Dr. John Sherwood Approved for The Graduate School Dr. Ronald W. Larsen iii STATEMENT OF PERMISSION TO USE In presenting this thesis in partial fulfillment of the requirements for a master’s degree at Montana State University, I agree that the Library shall make it available to borrowers under rules of the Library. If I have indicated my intention to copyright this thesis by including a copyright notice page, copying is allowable only for scholarly purposes, consistent with “fair use” as prescribed in the U.S. Copyright Law. Requests for permission for extended quotation from or reproduction of this thesis in whole or in parts may be granted only by the copyright holder. Ryan Lane Quire April 2013 iv ACKNOWLEDGEMENTS This research project would not have been possible without funding from the National Science Foundation to image more than 50,000 plant specimens from the Montana State University Herbarium. I would especially like to thank Dr. Matt Lavin for sharing his vast knowledge, continuous support and positivity, and for being one of the most patient people I’ve ever known. I am forever grateful for this incredible experience. I would like to thank my other committee members Dr. Lisa Rew and Dr. Bruce Maxwell for their assistance and support. Dr. Dave Roberts helped immensely with my understanding of multivariate statistics, which greatly enhanced the thought that has gone into this thesis. Jay Rotella kindly assisted with the model selection approaches used in this study. Additionally, Tyler Brummer generously assisted with the study design and data collection in the Idaho National Laboratory. I would also like to thank my sweet parents, Scott and Kay Quire, for loving and believing in me, and instilling independence in me. And finally, without the encouragement and compassion of my wonderful friends, I wouldn’t be where I am today. v TABLE OF CONTENTS 1. THE SAGEBRUSH STEPPE: A REVIEW OF THE ECOLOGICAL LITERATURE ......................................................................................1 Introduction ......................................................................................................................1 The Species of Sagebrush ................................................................................................2 The Geographic Scope of the Sagebrush Steppe .............................................................3 Sagebrush Steppe Climate and Ecological Stability ........................................................6 Sagebrush Steppe Habitat Types in Montana ................................................................10 Habitat Research on the Sagebrush Steppe ....................................................................15 Removal of Sagebrush to Enhance Range Quality ........................................................17 Studies of Plant Diversity in the Sagebrush Steppe .......................................................20 Fire Effects on Sagebrush Steppe Plant Diversity .........................................................24 Summary Remarks .........................................................................................................26 Literature Cited ..............................................................................................................28 2. HYPOTHESES, MATERIALS AND METHODS .......................................................38 Research Questions and Objectives ...............................................................................38 Specific Questions to be Addressed in This Study ................................................41 Botanical Nomenclature and Nativity Status .................................................................43 Study Sites .....................................................................................................................43 Transect Descriptions and Establishment ..............................................................45 The Community Phylogeny ...........................................................................................48 Response Variable .........................................................................................................50 Explanatory Variables ....................................................................................................56 Diversity Indices ............................................................................................................57 Explanatory Variable Selection .....................................................................................60 Canonical Correspondence Analysis .............................................................................62 Ordination ......................................................................................................................63 Literature Cited ..............................................................................................................64 3. RESULTS OF THE PLANT BIODIVERSITY ANALYSIS IN THE SAGEBRUSH STEPPE OF MONTANA AND SOUTHEASTERN IDAHO ..........................................................................................69 Alpha Diversity ..............................................................................................................69 Model Selection Results ................................................................................................77 Response Variable Selection..................................................................................77 Ordination ..............................................................................................................84 Explanatory Variables: Choosing a Candidate Set ................................................85 A Bioclimatic Model of Plant Biodiversity in the Sagebrush Steppe ....................90 Categorical Explanatory Variables ........................................................................92 vi TABLE OF CONTENTS - CONTINUED Canonical Correspondence Analysis .....................................................................95 Geographic Distance ......................................................................................................96 Influence of Geographic Proximity on Local Species Pools .................................98 Distinguishing Nonnative and Native Species Within Disturbance Categories ........................................................................................106 4. DISCUSSION OF PLANT BIODIVERSITY IN THE SAGEBRUSH STEPPE OF MONTANA AND SOUTHEASTERN IDAHO ...........110 Introduction ..................................................................................................................110 Alpha Diversity of Plants in the Sagebrush Steppe .....................................................112 Species Beta and Phylogenetic Beta Diversity of Plants in the Sagebrush Steppe ....................................................................................114 Ecological Stability of the Sagebrush Steppe ..............................................................115 The Diversity Invasibility Hypothesis and Ecological Stability ..........................117 Dispersal Limitation.............................................................................................118 Restoration Benchmarks ..............................................................................................120 Reclamation Species Pools ..........................................................................................121 Conclusion ...................................................................................................................122 Literature Cited ............................................................................................................125 REFERENCES CITED ....................................................................................................128 APPENDICES .................................................................................................................145 APPENDIX A: Sagebrush Steppe Transect Map Data Dictionary .....................146 APPENDIX B: List of Sample Sites ....................................................................148 APPENDIX C: Phylomatic Species Classification List ......................................152 APPENDIX D: Candidate Native Species for Restoration Benchmarks in Sagebrush Steppe .......................................................................167 APPENDIX E: Candidate Native Species for Immediate Reclamation in Degraded Sagebrush Steppe .......................................................184 vii LIST OF TABLES Table Page 2.1 Bioclimatic variables derived from WorldClim ....................................................57 3.1 Correlation