California State University, Monterey Bay Digital Commons @ CSUMB SNS Master's Theses School of Natural Sciences Fall 2011 An Assessment of Control Methods for Cape Ivy in Coastal Riparian Ecosystems Jennifer Stern California State University, Monterey Bay Follow this and additional works at: https://digitalcommons.csumb.edu/sns_theses Recommended Citation Stern, Jennifer, "An Assessment of Control Methods for Cape Ivy in Coastal Riparian Ecosystems" (2011). SNS Master's Theses. 16. https://digitalcommons.csumb.edu/sns_theses/16 This Master's Thesis (Open Access) is brought to you for free and open access by the School of Natural Sciences at Digital Commons @ CSUMB. It has been accepted for inclusion in SNS Master's Theses by an authorized administrator of Digital Commons @ CSUMB. For more information, please contact [email protected]. An Assessment of Control Methods for Cape ivy in Coastal Riparian Ecosystems A Thesis Presented to the Faculty of the Division of Science and Environmental Policy California State University Monterey Bay In Partial Fulfillment ofthe Requirements for the Degree Master of Science In Coastal and Watershed Science and Policy by Jennifer Stem Fa112011 CALIFORNIA STATE UNIVERSITY MONTEREY BAY The Undersigned Faculty Committee Approves the Thesis of Jennifer Stem In Partial Fulfillment of the Requirements for the Degree Master of Science in Coastal and Watershed Science and Policy AN ASSESSMENT OF CONTROL METHODS FOR CAPE IVY IN COASTAL RIPARIAN ECOSYSTEMS Fred Watson, Committee Chair Division of Science and Environmental Policy ~' ~ .. ~ :"':?1/Llc~vi-rA. Suzanne Worcester Division of Science and Environmental Policy ./::;._<;7 '// . j ~.. // ~j{!Jf:.~, 7' . /.// George McMenamin t!'est<JfUtion Consulting, Santa Cruz County Marsha Moroh, Dean College of Science, Media Arts, and Technology Fall 2011 111 Copyright © 2011 by Jennifer Stem All Rights Reserved IV DEDICATION I dedicate this thesis to my Mom, Tracy, who always followed her dreams and encouraged me to do the same. v ABSTRACT The goals ofthis research were to quantify the achievable outcomes and associated costs of controlling Cape ivy (Delairea odorata), a non-native invasive plant. Current gaps in the knowledge-base limit decision makers from assigning appropriate costs, and therefore funding, for invasive species control (D'Antonio and Chambers 2006). Towards these goals, I measured and compared the success and cost-effectiveness of three control methods on Cape ivy in riparian areas along the Central Coast region of California. The control methods used in this study included hand removal, herbicide application (glyphosate), and a combination ofthese two methods. Control methods were applied to Cape ivy infestations at three research sites; two within Santa Cruz County and one in Monterey County, beginning July 2008 and concluding September 2009. Success ofeach control method was measured by comparison ofpre and post-treatment vegetation sampling. The costs associated with each method (labor, herbicides, materials) were also recorded for each method. After twelve months, the hand removal method achieved the highest reduction ofCape ivy cover and resulted in the highest native plant cover. However, the most cost-effective method (per dollar) for the first twelve months of Cape ivy control was the herbicide only method. The results ofthis study will be provided to staff at California State Parks, the Land Trust of Santa Cruz County, and the Big Sur Land Trust to inform future management of Cape ivy on their properties. Additionally, this research will contribute to needed guidelines for restoration ofCape-ivy infested riparian ecosystems, and serve as a resource for researchers interested in control of invasive plants and restoration of disturbed areas. VI TABLE OF CONTENTS PAGE ABSTRACT ......................................................................................................................................V LIST OF TABLES ......................................................................................................................... VIII LIST OF FIGITRES ....................................................................................................................... VIII ACKNOWLEDGEMENTS ............................................................................................................ IX INTRODUCTION ........................................................................................................................... 1 SPECIFIC GOALS AND OBJECTIVES ...................................................................................... 3 Hypotheses .................................................................................................................................... 3 METHODS....................................................................................................................................... 5 Study Area Description .................................................................................................................. 5 Selection of Treatment Methods................................................................................................... 7 Sampling Unit and Plot Design ...................................................................................................... 9 Treatment Techniques ................................................................................................................. 11 Timing Of Treatment Applications .............................................................................................. 12 Vegetation Sampling ................................................................................................................... 13 Cost-Effectiveness........................................................................................................................ 13 Statistical Analysis ....................................................................................................................... 13 RESULTS ....................................................................................................................................... 15 Effects on Cape Ivy Cover ............................................................................................................ 15 Effects On Native Plant Cover.................................................... .................................................. 17 Associated Costs Of Treatments.................................................................................................. 19 DISCUSSION................................................................................................................................. 21 Monitoring................................................................................................................................... 22 Management Recommendations................................................................................................ 22 CONCLUSION .............................................................................................................................. 23 REFERENCES ................................................................................................................................... 25 ApPENDIX A .................................................................................................................................... 32 Science Policy Context ................................................................................................................. 32 Background .. .............................................................................................................................., 36 Applicable Theory.I ......,..............,...." .."., .. ,.".,." .. 1" •• ' ••• , •••• " •• II ••••• t.".' •• , •• ,I."fff •• 'tt"f.t.,1." •• 1•••• , •••• 41 VB ApPENDIX B .................................................................................................................................... 43 Cape Ivy Control Field Experiments and Trials ............................................................................ 43 ApPENDIX C .................................................................................................................................... 46 AIC Tables for Cape ivy Treatment Method Comparison ............................................................ 46 ApPENDIX D .................................................................................................................................... 48 Pre- and Post-Treatment Native Plant Cover Sampling Results for each site ............................. 48 ApPENDIX E .................................................................................................................................... 51 Cost Trocking Tables for Cape ivy Treatment Methods ............................................................... 51 ApPENDIX F .................................................................................................................................... 56 Total Costs for Cape ivy Treatment Methods .............................................................................. 56 APPENDIX G ................................................................................................................................. 59 R Code Used In Statistical Analyses ............................................................................................. 59 APPENDIX H ................................................................................................................................