Evaluating the Effects of Mechanical and Manual
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EVALUATING THE EFFECTS OF MECHANICAL AND MANUAL REMOVAL OF Ammophila arenaria WITHIN COASTAL DUNES OF HUMBOLDT COUNTY ____________ A Thesis Presented to the Faculty of California State University, Chico ____________ In Partial Fulfillment of the Requirements for the Degree Master of Science in Biological Sciences ____________ by Ayla Joy Mills Spring 2015 EVALUATING THE EFFECTS OF MECHANICAL AND MANUAL REMOVAL OF Ammophila arenaria WITHIN COASTAL DUNES OF HUMBOLDT COUNTY A Thesis by Ayla Joy Mills Spring 2015 APPROVED BY THE DEAN OF GRADUATE STUDIES AND VICE PROVOST FOR RESEARCH: _________________________________ Eun K. Park, Ph.D. APPROVED BY THE GRADUATE ADVISORY COMMITTEE: ______________________________ _________________________________ Guy Q. King, Ph.D. Kristina Schierenbeck, Ph.D., Chair Graduate Coordinator _________________________________ Colleen Hatfield, Ph.D. ______________________________ _________________________________ Guy Q. King, Ph.D. Adrienne Edwards, Ph.D. ACKNOWLEDGMENTS I would like to thank my advisor and committee chair Kristina Schierenbeck. She has given me great advice and assistance throughout the process. I would also like to thank my knowledgeable committee members Colleen Hatfield and Adrienne Edwards. A special thanks to Amber Transou and California State Park’s North Coast Redwood District for providing me with guidance, funding, equipment, and for making this project possible. I’d like to thank my wonderful husband Jason who helped me set up my plots and collect data, even when it was cold and raining. I couldn’t have done it without you. I would like to thank my Mom who helped me financially and emotionally make it through graduate school. I would also like to thank my best friend Krystal Godfrey for always being there to listen to me vent and also for helping collect data. Nancy Carter deserves a big thanks for helping me statistically analyze my data and for being a great teacher. The Chico State Associated Students Sustainability Fund provided me with funding for the materials required for setting up and monitoring my experimental plots. I would also like to thank my friends, and Chico State Alumni, Tony Vertolli and Aurelia Gonzalez for helping me collect data. I would also like to thank the California Native Plant Society’s Mt. Lassen Chapter and the Chico State Biology Department for funding trips to present my research at the Centennial Celebration of the California Botanical Society and the CNPS Conservation Conference. iii TABLE OF CONTENTS PAGE Acknowledgments ...................................................................................................... iii List of Tables.............................................................................................................. vi List of Figures............................................................................................................. viii Abstract....................................................................................................................... x CHAPTER I. Introduction.............................................................................................. 1 II. Literature Review..................................................................................... 7 The State of the Coast................................................................... 7 California Coastal Dunes.............................................................. 8 Geology ........................................................................................ 8 Climate ......................................................................................... 9 Soils .............................................................................................. 10 Dune Plant Adaptations................................................................ 10 Dune Morphology ........................................................................ 11 Common Dune Mat Plant Species of Northern California........... 13 Study Species................................................................................ 15 III. Methods.................................................................................................... 19 Study Area.................................................................................... 19 Project Plan................................................................................... 20 Removal........................................................................................ 20 Monitoring.................................................................................... 22 Time Comparison Monitoring...................................................... 25 Statistical Analysis ....................................................................... 26 iv CHAPTER PAGE IV. Results...................................................................................................... 28 A. arenaria before Treatment and Within the Control Sites ........ 28 Analysis of the Treatment Method of A. arenaria ....................... 29 Analysis of the Monitoring Time Intervals for A. arenaria ......... 30 Analysis of the Interaction Between Treatment and Monitoring Time Interval for A. arenaria ............................ 32 Analysis of the Treatment for Native Plant Recovery After A. arenaria Removal ................................................... 33 Analysis of the Monitoring Time Intervals for Native Plant Recovery After A. arenaria Removal.......................... 33 Analysis of the Interaction Between Treatment and Monitoring Time Interval for Native Plants ......................... 34 Analysis of the Treatment and Time Interval for Other Non-native Plants After A. arenaria Removal...................... 34 Analysis of the Interaction Between Treatment and Monitoring Time Interval for Other Non-native Plants........ 36 Analysis of the Time Comparison Sites ....................................... 37 V. Discussion................................................................................................. 44 VI. Conclusions.............................................................................................. 53 Literature Cited........................................................................................................... 55 Appendices A. Plant Species List for Gold Bluffs Beach................................................. 64 B. Plant Species List for Little River and Clam Beach................................. 67 v LIST OF TABLES TABLE PAGE 1. Dates of Initial Mechanical Removal and Manual Removal of A. arenaria at Gold Bluffs Beach .................................................. 22 2. Modified Braun-Blanquet Cover Scale Used to Estimate Percent Cover Values for Vegetation Within Quadrats ..................... 24 3. Project Timeline Including Vegetation Monitoring Dates at Time Zero (Before Initial Removal of A. arenaria Occurred), 3 Months Post-Removal, 6 Months Post-Removal, and 12 Months Post-Removal Occurred at Gold Bluffs Beach ................ 24 4. Time frame in which monitoring and removal of A. arenaria occurred at the time comparison sites ................................................ 25 5. Mean Cover Class Values (± SD) for A. arenaria and Tukey Pairwise Comparisons of Treatment and Monitoring Time Interval Interactions .................................................................. 29 6. Mean Cover Class Values (± SD) for A. arenaria and Tukey Pairwise Comparisons of Treatment Method (Mechanical, Hand, and Control) Averaged over All the Time Frames .................. 31 7. Mean Cover Class Values (± SD) for A. arenaria and Tukey Pairwise Comparisons of Monitoring Time Interval (Time Zero, 3 Months, 6 Months, and 12 Months Post-Removal) When Averaged over All the Treatments........................................... 32 8. Mean Cover Class Values (± SD) for Native Plants and Tukey Pairwise Comparisons of Monitoring Time Interval (Time Zero, 3 Months, 6 Months, and 12 Months Post-Removal) When Averaged over All the Treatments........................................... 33 9. Mean Cover Class Values (± SD) for Native Plants and Tukey Pairwise Comparisons of Treatment and Monitoring Time Interval Interactions............................................................................ 35 vi TABLE PAGE 10. Mean Cover Class Values (± SD) for Other Non-Native Plants and Tukey Pairwise Comparisons of Treatment and Monitoring Time Interval Interactions ....................................... 38 11. Mean Cover Class Values (± SD) and Tukey Pairwise Comparisons for A. arenaria regrowth and Native Plant Recovery at the Time Comparison Sites ............................................ 40 vii LIST OF FIGURES FIGURE PAGE 1. Map of Gold Bluffs Beach Divided into Blocks 1-7 ................................ 21 2. Experimental Design Used to Examine Treatment Effects ...................... 23 3. Interaction Plot for A. arenaria Removal Showing Differences Between the Hand Treatment (in Red), Mechanical Treatment (in Green), and the Control Treatment (in Blue) Across Time Intervals (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal) at Gold Bluffs Beach............................................................................... 30 4. Interaction Between Treatments (Hand (H), Mechanical (M), and Control(C)) and Monitoring Time Interval (Time Zero, 3 Months After Removal, 6 Months After Removal, and 12 Months After Removal) of A. arenaria at Gold Bluffs Beach ........... 31 5. Interaction Plot for Native