Grand Valley State University ScholarWorks@GVSU Masters Theses Graduate Research and Creative Practice 8-2018 Assessment of invasive Gypsophila paniculata Control Methods in the northwest Michigan dunes Emma K. Rice Grand Valley State University Follow this and additional works at: https://scholarworks.gvsu.edu/theses Part of the Biology Commons Recommended Citation Rice, Emma K., "Assessment of invasive Gypsophila paniculata Control Methods in the northwest Michigan dunes" (2018). Masters Theses. 888. https://scholarworks.gvsu.edu/theses/888 This Thesis is brought to you for free and open access by the Graduate Research and Creative Practice at ScholarWorks@GVSU. It has been accepted for inclusion in Masters Theses by an authorized administrator of ScholarWorks@GVSU. For more information, please contact [email protected]. Assessment of invasive Gypsophila paniculata Control Methods in the northwest Michigan dunes Emma K. Rice A Thesis Submitted to the Graduate Faculty of GRAND VALLEY STATE UNIVERSITY In Partial Fulfillment of the Requirements For the Degree of Master of Science in Biology Department of Biology August 2018 Dedication To my father, for instilling in me a sense of wonder for the natural world and love of scientific inquiry, and to my mother for her steadfast support and willingness to proofread endless versions of this thesis. 3 Acknowledgements I would like to thank all of the individuals that made this thesis possible. First, I would like to thank The Nature Conservancy and National Park Service for partnering with us on this project, their removal crews for the incredible work in managing G. paniculata and willingness to coordinate treatment timing and location. I thank my graduate advisor, Dr. James McNair, for his guidance, support and enthusiasm throughout this project. I would also like to thank my co- principal investigator and graduate committee member, Dr. Charlyn Partridge for the additional support, advice and aid with field work. My other graduate committee members, Dr. Timothy Evans and Dr. Daniel Frobish, for providing advice and support whenever sought. Thanks to Hailee Leimbach-Maus for being an incredible baby’s breath co-researcher and never hesitating to lend a helping hand. I thank Kurt Thompson, Kim Oldenborg, Matt Kienitz, Emily Dusicska, Alexis Hoskins and Pamela Martínez-Oquendo for their assistance with field work and mapping for this study. Funding for this research was provided by the U.S. EPA Great Lakes Restoration Initiative to Charlyn Partridge, James McNair, and Kevin Strychar. Additional funding was provided by the Presidential Research Grant through Grand Valley State University. 4 Abstract Gypsophila paniculata is an invasive species in Michigan’s northern lower peninsula and a problem invasive in much of the northern United States and Canada. Gypsophila paniculata readily outcompetes native plants in sandy, well-drained soils due to its deep taproot, which allows access to scarce resources. It reproduces and disperses mainly by seed, but the phenology of seed maturation is poorly understood. Gypsophila paniculata is of particular concern in lakeshore dunes because the areas where it is most dense are also populated by several endemic and threatened species. Despite many years of intensive management, high densities of G. paniculata persist in previously treated areas. To determine why this occurs, our research assessed current removal methods (foliar application of glyphosate and manual removal) by (1) measuring G. paniculata density and frequency over a large area using a point-intercept grid before and after treatment from 2016-2018, (2) investigating how timing of treatment affects G. paniculata density, (3) determining the resprout frequency of treated plants, (4) characterizing the local seed-maturation phenology and (5) investigating how timing of treatment affects resprouting and seed germination. Our results confirm that treatment for one or two years reduces the density of G. paniculata but does not extirpate it, overall treatment is most effective from late June through early July, and a small percentage of manually removed plants and herbicide-treated plants resprout following treatment. Seed germinability increased quickly at the end of July and reached a maximum of 90% or higher by early August in both 2016 and 2017. The germinability of seeds from plants sprayed with glyphosate in early, mid, and late July 2016 was higher the later treatment was administered, highlighting the need to treat early in the 5 growing season. To effectively control G. paniculata, we recommend that managers treat for consecutive years to remove regrowth and missed plants and focus treatment from late June to early July for best control, including prevention of seed maturation. Ultimately, this information will contribute to an adaptive management plan specific to baby’s breath that can be used in infested areas throughout northern North America. 6 Table of Contents List of Tables ............................................................................................................................ 11 List of Figures ........................................................................................................................... 12 Abbreviations ............................................................................................................................ 14 Chapter 1: Introduction ............................................................................................................ 15 Invasive species impacts .................................................................................................... 15 Adaptive management ....................................................................................................... 16 Methods for invasive species control ................................................................................. 17 Gypsophila paniculata in northwest Michigan ................................................................... 19 Purpose ................................................................................................................................. 20 Scope .................................................................................................................................... 20 Assumptions ......................................................................................................................... 20 Research Questions…………………………………………………………………………... 21 Significance .......................................................................................................................... 21 References ............................................................................................................................ 23 Chapter 2: Assessment of Invasive Gypsophila paniculata Control Methods in the Northwest Michigan Dunes ........................................................................................................................ 26 Abstract................................................................................................................................. 26 Restoration Recap ................................................................................................................. 27 Introduction........................................................................................................................... 27 Methods………………………………………………………………………………………. 30 Treatment Methods ........................................................................................................... 30 7 Point-Intercept Surveys ..................................................................................................... 30 Timing of Treatment ......................................................................................................... 32 Resprout Following Treatment .......................................................................................... 33 Results .................................................................................................................................. 34 Point-Intercept Survey ....................................................................................................... 34 Timing of Treatment ......................................................................................................... 35 Resprout Following Treatment .......................................................................................... 36 Discussion ............................................................................................................................. 36 Conclusions and Management Implications ....................................................................... 39 Acknowledgements ............................................................................................................... 40 References ............................................................................................................................ 41 Figures .................................................................................................................................. 45 Chapter 3: Phenology of Seed Maturation in Gypsophila paniculata and Its Relation to Glyphosate Efficacy .................................................................................................................. 49 Abstract................................................................................................................................. 49 Restoration Recap ................................................................................................................