4445 UNIVERSITYOF HAWAI" LIBRARY PHENOLOGY, REPRODUCTIVE POTENTIAL, SEED DISPERSAL AND PREDATION, AND SEEDLING ESTABLISHMENT OF THREE INVASIVE PLANT SPECIES IN A HAWAIIAN RAIN FOREST A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI'I IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN BOTANY MAY 2004 By Arthur C. Medeiros Dissertation Committee: Gerald Carr, Chairperson Sheila Conant David Duffy Lloyd Loope Robert Robichaux DEDICATION PAGE: This work is dedicated to the memory of a brilliant and beloved mentor, Dr. Charles lamoureux, a model teacher, a pioneering scientist in Hawai'i, and a great person. iii ACKNOWLEDGEMENTS This research project was made possible only through support by the Natural Resource Preservation Program (NRPP) of the U.S. Geological Survey (USGS) and support of the Pacific Island Ecosystems Research Center (PIERC) of the USGS. Mahalo loa to Dr. William Steiner and Dr. David Helweg, who head the research center. Mahalo loa to my dissertation committee: Dr. Gerald Carr (chairperson), Dr. Sheila Conant, Dr. David Duffy, Dr. Lloyd Loope, and Dr. Robert Robichaux. My chairperson Dr. Gerald Carr has been a conscientious and warm mentor who has made my graduate experience uncommonly rewarding. Dr. Sheila Conant has always been in my mind a sterling example of what excellence over time is all about. Dr. David Duffy, stepped bravely in to replace committee member Dr. Charles Lamoureux who died unexpectedly in 2001. Dr. Duffy's skills as an editor and his keen intellect have benefited this dissertation substantially. Dr. Lloyd Loope helped develop the initial concepts and scope of the research project which turned out to be my dissertation project. He counseled me throughout and kept me centered on work which would have the greatest value in conservation and management. Dr. Robert Robichaux has served beyond the normal call of duty, as a friend, counsel, and advisor. His thoughts and critiques shaped this work and increased its contribution to the growing literature on invasive species. tV Mahalo loa to the conscientious and professional staff at Haleakala National Park (HALE) for assistance with and access to the closed scientific reserve, KTpahulu Valley. At HALE, I thank Superintendent Donald Reeser, Chief of Resources Management Ronald J. Nagata, Head of Vegetation Management Steven Anderson, and botanists Patty Welton and William Haus. Mahalo loa to the Maui Division of Forestry and Wildlife for access to Makawao Forest Reserve, especially then District Forester Robert Hobdy and Wildlife Biologist Dr. Fern Duvall. A special mahalo loa to Ellen VanGelder, Charles Chimera, Paul Krushelnycky, and Stephanie Joe for critical assistance in field work for this project. Without their efforts, this work simply would not have been possible. Mahalo loa to Cathy Davenport, Peter Dunlevy, Jean-Yves Meyer, and Mike Townsend for additional field assistance. Mahalo loa to Dr. Gregory Massey for his guidance and assistance in care of wild passerine birds and Peter Dunlevy for his skillful construction of the predator-proof bird holding structure used for the gastrointestinal passage time experiment. Mahalo loa to staff and pilots of Windward Aviation and Pacific Aviation especially pilots Duke Baldwin and Don Shearer for their high standards of safety in frequent trips to KTpahulu Valley, and to Ronald J. Nagata, Haleakala National Park Aviation Officer who administered flight activities. v Mahalo loa to Dr. Andy Taylor who served as the primary source of statistical help and guidance. Mahalo loa to Charles Chimera for guidance and stimulating discussions regarding the data-statistic interface and its role in effecting how we view the natural world. Mahalo loa to Forest Starr, Kim Starr, and Dan McNulty­ Huffman for crucial assistance in production of computer graphics. Mahalo loa to Steven Anderson, Pat Bily, Chuck Chimera, Melissa Chimera, Colleen Cory, William Haus, Robert Hobdy, Hank Oppenheimer, and Patti Welton for their generous sharing of field knowledge and to Dan McNulty­ Huffman of Haleakala National Park for his technical expertise in ArcView mapping software used in production of the distributional maps of the three study weeds on Haleakala. Mahalo loa to Dr. Paul Banko, Chuck Chimera, Dr. Fern Duvall, the late Dr. Charles Lamoureux, Dr. Lloyd Loope, Dr. Jean-Yves Meyer, Dr. Thane Pratt, Dr. Robert Robichaux, and Dr. Clifford Smith for many stimulating comments and discussion which inevitably honed the ultimate aims, methods, and conclusions of this work. Mahalo loa to Pacific Cooperative Studies Unit (PCSU) headed by Dr. David Duffy and his predecessor Dr. Clifford Smith, as well as Lynnette Kinoshita, for their help and support. Vi ABSTRACT The objective of this study was to investigate phenology, reproductive potential, seed dispersal and predation, and seedling establishment of three important weed species (Clidemia hirta, Hedychium gardnerianum, Psidium cattleianum) of Hawaiian rain forests. The phenology results revealed that Clidemia ripe fruit production was highest from October through January, Hedychium from October through December, and Psidium in November. Compared to Psidium of similar sizes at lower elevations, the production of ripe fruit by Psidium at the study site appeared limited. Clidemia was estimated to produce more than four orders of magnitude more seeds than Hedychium and Psidium of equal cover. Individual Clidemia plants, which averaged 0.37 m2 cover, produced an average of 3,815,552 seeds/yr. Birds, especially two common non-native species (Zosterops japonicus and Leiothrix lutea), are dispersing all three weed species as well as at least six native plant species, one non-native species, and four unidentified species. Under experimental conditions, the passage time for Clidemia seeds was as long as 210 minutes, for Hedychium seeds as long as 270 minutes, and with limited results, for Psidium seeds less than 60 mihutes. Non-native rats (Rattus spp.) were discovered to be dispersing viable Clidemia seeds that did not differ significantly in germinability or germination rate from control seeds. Non­ native rats were also discovered to have caused a 48.3% reduction in Hedychium seed production through flower bud, flower, and pre-dispersal seed predation. The final objective of this investigation was to determine which sites Vll are suitable for germination and initial seedling growth of the study species. Results from Clidemia sites (but not Hedychium and Psidium) indicated a large, viable seed bank and/or substantial seed rain. Clidemia produced the greatest number and heights of seedlings in scalped and grassy sites. Hedychium produced the greatest number of seedlings in epiphytic sites and the least in grassy sites. Psidium were found in three site types, with the tallest seedlings being found in fernland sites. Data from the last part of this investigation suggest that Clidemia is disturbance-adapted and less adapted to protected, shaded sites, whereas Hedychium and Psidium are greater threats to recovering and intact rain forests. Vlll TABLE OF CONTENTS Dedication iii Acknowledgements '" ,. '" '" , iv Abstract. '" .. ,, '" ,. '" '" , vii List of Tables '" , '" , xi List of Figures xiv Chapter 1. Introduction 1 Abstract. 2 Introduction '" '" 3 Global overview of invasive species , 3 Biological invasions in Hawai'i. , '" '" 6 Properties of invasive species 8 Study system , '" '" ,. '" '" , 13 Study area '" ,. '" '" '" 13 Study species , .,. " 15 Objectives '" , '" '" 28 General objectives 28 Specific hypotheses 28 Methods 29 Discussion 34 Chapter 2. Phenology and reproductive potential estimates for three important invasive plant species of native rain forest at Kipahulu, Maui, Hawaiian Islands 38 Abstract. , '" , '" 39 Introduction , '" '" 40 Material and methods '" '" , '" 43 Results 49 Phenology , 49 Estimates of reproductive potential. '" 60 Discussion '" , 62 Conclusions 68 IX Chapter 3. Avian seed dispersal of three important weed species in an East Maui rain forest, Hawaiian Islands '" , 70 Abstract '" '" 71 Introduction '" ," 72 Material and methods '" , '" '" 76 Results '" ., , '" '" 90 Study species , .. , 90 Other dispersed plant species 96 Discussion , '" '" , 106 Chapter 4. Pre-dispersal seed predation and dispersal of invasive weed species by non-native rodents in a Hawaiian rain forest. .. '" '" 117 Abstract. .. '" '" , 118 Introduction , , 119 Material and methods '" '" ,.. 121 Results , ,.. 128 Discussion , '" 137 Chapter 5. Differential establishment of three invasive weed species in ecosites of a Hawaiian rain forest, Maui, Hawai'i. 143 Abstract. " , '" ,.. 144 Introduction 145 Material and methods '" , 152 Results ,, '" ," 157 Discussion , '" '" '" 162 Conclusions , '" '" , '" 174 Chapter 6. Conclusions ,.. 179 Appendix A. Comparison of area and species diversity of Hawai'i and the United States 191 Appendix B. Composition of invertebrate prey of six wild-caught rain forest bird species, Maui '" '" .. , , ,......... ... 192 Appendix C. List of flowering plants of Kipahulu Valley and their putative seed dispersal methods ,.. 193 Appendix D. Analysis of rodent droppings collected within fruiting weed patches at East Maui study sites '" '" 199 Literature cited ,", '" " 205 x LIST OF TABLES TABLE PAGE Table 1. Naturalized range of Clidemia hirta ., '" 17 Table 2. Naturalized range of Hedychium gardnerianum 21 Table 3. Naturalized range of Psidium cattleianum 25 Table 4. Mean numbers of flower buds, flowers,