THE ECOLOGY AND INTEGRATED MANAGEMENT OF TALL BUTTERCUP (RANUNCULUS ACRIS L.) by Hally Kirsten Strevey A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Land Rehabilitation MONTANA STATE UNIVERSITY Bozeman, Montana May 2014 ©COPYRIGHT by Hally Kirsten Strevey 2014 All Rights Reserved ii ACKNOWLEDGEMENTS I would first like to thank my advisor, Dr. Jane Mangold for her support, encouragement, and humor throughout my career as a graduate student. I believe that the guidance and feedback from a major advisor is crucial for a successful experience in graduate school, and I know that I can attribute my accomplishments to the help she has provided me. I also would like to thank my committee members, Drs. Cathy Zabinski and Jim Jacobs. I have appreciated their feedback and advice throughout my program. My field sites were not always the most pleasant places to be (we were never dry- either wet from dew or sweat, mosquitoes buzzing in your ear all day long, and the giant spiders that would often crawl up our legs), so I have to thank Noelle Orloff, Torrin Daniels, Daniel France and James Collins for their hard work and perseverance and for sticking it out with me when times got tough in the tall buttercup field. I would also like to thank my lab-mates Christina Herron-Sweet, Krista Ehlert, Noelle Orloff and Hilary Parkinson for not only providing me with knowledge and advice ranging from statistics to writing, but for also providing me with comedic relief and friendship. Cooperation was appreciated from Margie Edsall, and landowners Dave Ashcraft, and Luke and Duke Novich for allowing me to utilize their land for my study sites and for both recognizing the need for this research and for their continued support of the project. Thank you also to the Montana Noxious Weed Trust Fund for providing the funding for this research. Finally I would like to thank my husband, Scott Strevey, for supporting me through the trials and tribulations of graduate school, my family for their advice and love, and I would finally like to acknowledge the beautiful wild places I love that continue to inspire me. iii TABLE OF CONTENTS 1. PROJECT BACKGROUND AND OBJECTIVES .........................................................1 Introduction .....................................................................................................................1 Literature Review............................................................................................................3 Distribution and Habitat ...........................................................................................3 Irrigation and Occurrence of Tall Buttercup ................................................4 Identification ............................................................................................................6 Life History ..............................................................................................................7 Impacts of Tall Buttercup ......................................................................................12 Ecological Impacts .....................................................................................12 Glycoside Ranunculin ................................................................................12 Economic Impacts .....................................................................................13 Potential Impacts in Montana ...................................................................14 Integrated Management Approaches to Control Tall Buttercup ............................15 Prevention ..................................................................................................16 Herbicides ..................................................................................................18 Mowing ......................................................................................................19 Fertilization ................................................................................................20 Biological Control ......................................................................................22 Grazing Management .................................................................................24 Irrigation ....................................................................................................25 Impacts of Invasive Plants on Species Richness and Diversity ............................25 Project Justification and Objectives ...............................................................................28 2. ASSESSING THE ASSOCIATIONS OF TALL BUTTERCUP ON SPECIES RICHNESS, PLANT DIVERSITY AND FORAGE PRODUCTION ...................................................................................30 Introduction ....................................................................................................................30 Materials and Methods ...................................................................................................32 Site Description ......................................................................................................32 Experimental Design ..............................................................................................33 Vegetation and Soil Moisture Sampling ................................................................33 Statistical Analysis .................................................................................................35 Results ............................................................................................................................37 Perennial Grass ......................................................................................................37 Grass-like Species ..................................................................................................39 Exotic Forbs ...........................................................................................................41 Native Forbs ...........................................................................................................43 Individual Species of Interest.................................................................................43 iv TABLE OF CONTENTS - CONTINUED Species Richness ....................................................................................................45 Plant Diversity .......................................................................................................45 Gravimetric Soil Water and Tall Buttercup ...........................................................45 Discussion ......................................................................................................................48 Management Implications ..............................................................................................56 3. INTEGRATED MANAGEMENT OF TALL BUTTERCUP IN MONTANA HAYFIELD MEADOWS ...................................................................58 Introduction ....................................................................................................................58 Materials and Methods ...................................................................................................61 Site Description ......................................................................................................61 Experimental Design ..............................................................................................62 Vegetation Sampling ..............................................................................................63 Soil Nutrient Sampling ..........................................................................................64 Statistical Analysis .................................................................................................65 Results ............................................................................................................................66 Tall Buttercup (TB)................................................................................................66 Ashcraft Site...............................................................................................66 Novich Site.................................................................................................69 Perennial Grass (PG)..............................................................................................72 Ashcraft Site...............................................................................................72 Novich Site.................................................................................................74 Grass-like Species (GL) .........................................................................................75 Ashcraft Site...............................................................................................75 Novich Site.................................................................................................76 Exotic Forbs (EF) ...................................................................................................76 Ashcraft Site...............................................................................................76 Novich Site.................................................................................................76 Native Forbs (NF) ..................................................................................................78 Ashcraft Site...............................................................................................78