RESTORING NATIVE PLANT AND ARTHROPOD COMMUNITIES IN GULF COASTAL PRAIRIES FOLLOWING PLANT INVASION AND DROUGHT by Adam Benjamin Mitchell A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Fish and Wildlife Management MONTANA STATE UNIVERSITY Bozeman, Montana July 2014 ©COPYRIGHT by Adam Benjamin Mitchell 2014 All Rights Reserved II ACKNOWLEDGEMENTS I would like to thank my advisor, Dr. Andrea Litt, for her invaluable assistance in the conceptualization, development, and synthesis of the study. Her involvement and encouragement throughout this process is a testament to her ability as a mentor and as a scientist, and I am honored to have had the opportunity to begin my career under her guidance. I am grateful to my committee members, Drs. Laura Burkle, Jane Mangold, and Cathy Zabinski, for their expertise that helped develop many components of the study. I also would like to thank Anthony Falk and Forrest Smith of the South Texas Natives for their knowledge and contributions to the study, and hope that this research will provide them with future directions towards restoring native plants throughout southern Texas. I am grateful to the staff and fellows at the Welder Wildlife Foundation for their constant support, encouragement, and unshakable morale. I am honored to have called myself a Welder Wildlife Fellow. I thank my fellow graduate students, especially Dan Bachen, Stacy Davis, Ross Hinderer, Erin Kenison, and Mike Simanonok, for their insight, encouragement, patience, and friendships that are worth more than I can say. Last, but certainly not least, I wish to extend my sincerest thanks to my family for their support and patience through this arduous journey. This thesis is dedicated to the people that made me who I am today—my mother, for encouraging my love of the outdoors, and my father, whose footsteps I inadvertently followed into this project. Funding for this project was provided by: Montana State University, the Montana Institute on Ecosystems, Texas Parks and Wildlife, and the Welder Wildlife Foundation. III TABLE OF CONTENTS 1. INTRODUCTION TO THESIS ............................................................................................. 1 Introduction ..................................................................................................................... 1 Literature Cited ............................................................................................................... 8 2. SHIFTS IN COMPOSITION OF PLANT AND ARTHROPOD COMMUNITIES FOLLOWING PLANT INVASION AND DROUGHT ............................................................ 16 Contributions of Authors and Co-Authors .................................................................... 16 Manuscript Information Page ........................................................................................ 17 Abstract ......................................................................................................................... 18 Introduction ................................................................................................................... 19 Methods ......................................................................................................................... 23 Study Area ............................................................................................................. 23 Vegetation Sampling ............................................................................................. 24 Soil Sampling ......................................................................................................... 25 Arthropod Sampling .............................................................................................. 26 Precipitation .......................................................................................................... 29 Data Analysis ......................................................................................................... 29 Results ............................................................................................................................ 31 Precipitation .......................................................................................................... 31 Vegetation ............................................................................................................. 31 Soils ....................................................................................................................... 33 Arthropods ............................................................................................................ 33 Herbivores ................................................................................................. 34 Decomposers ............................................................................................ 35 Predators ................................................................................................... 35 Ants ........................................................................................................... 36 Discussion ....................................................................................................................... 37 Herbivores ............................................................................................................. 38 Decomposers ........................................................................................................ 39 Predators ............................................................................................................... 41 Ants ....................................................................................................................... 42 Conclusions ........................................................................................................... 43 Literature Cited .............................................................................................................. 59 IV TABLE OF CONTENTS – CONTINUED 3. MODIFYING SOIL PROPERTIES TO RESTORE NATIVE PLANT COMMUNITIES FOLLOWING PLANT INVASION AND DROUGHT ................................... 70 Contributions of Authors and Co-Authors .................................................................... 70 Manuscript Information Page ....................................................................................... 71 Abstract ......................................................................................................................... 72 Introduction ................................................................................................................... 73 Methods ........................................................................................................................ 77 Study Area ............................................................................................................. 77 Field Study ............................................................................................................. 78 Treatment Application .......................................................................................... 79 Vegetation Sampling ............................................................................................. 80 Soil Sampling ......................................................................................................... 81 Precipitation .......................................................................................................... 81 Microcosm Study .................................................................................................. 82 Data Analysis ......................................................................................................... 83 Results ........................................................................................................................... 84 Precipitation .......................................................................................................... 84 Field Study ............................................................................................................. 84 Microcosm Study .................................................................................................. 86 Discussion ...................................................................................................................... 87 Conclusions ........................................................................................................... 93 Literature Cited ........................................................................................................... 102 4. SOIL MODIFICATION TO RESTORE NATIVE ARTHROPOD COMMUNITIES IMPACTED BY PLANT INVASION AND DROUGHT ........................................................ 113 Contributions of Authors and Co-Authors .................................................................. 113 Manuscript Information Page ..................................................................................... 114 Abstract ....................................................................................................................... 115 Introduction ................................................................................................................. 116 Methods ...................................................................................................................... 120 Study Area ........................................................................................................... 120 Treatment Application .......................................................................................