Demographic modeling of Hawaiian silverswords, and its implications for conservation Item Type text; Dissertation-Reproduction (electronic) Authors Forsyth, Stacey Ann Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 26/09/2021 03:56:21 Link to Item http://hdl.handle.net/10150/280173 INFORMATION TO USERS This manuscript has t)een reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. 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ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 DEMOGRAPHIC MODELING OF HAWAIL\N SILVERSWORDS, AND ITS IMPLICATIONS FOR CONSERVATION by Stacey Ann Forsyth Copyright £ Stacey Ann Forsyth 2002 A Dissertation Submitted to the Faculty of the DEPARTMENT OF ECOLOGY AND EVOLUTIONARY BIOLOGY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2002 UMI Number; 3073218 Copyright 2002 by Forsyth, Stacey Ann All rights reserved. UMI UMI Microform 3073218 Copyright 2003 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Leaming Company 300 North Zeeb Road P.O. Box 1346 Ann Artwr, Ml 48106-1346 THE raiVERSITY OF ARIZONA iS- GRADUATE COLLEGE As members of the Final Examination Committee, we certify that we have Stacey Ann Forsyth read the dissertation prepared by entitled DEMOGRAPHIC MODELING OF HAWAIIAN SILVERSWORDS, AND ITS IMPLICATIONS FOR CONSERVATION. and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of PhilosODhy If- ^-OTs Kobert KODTcnaux Date /Judith Bronstein Date ' iT-/^ ,Lucinda McDade Date Martha hunter Date Date Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ij' Dissertation Director Robert ROblchaux Datle ' STATEMENT BY AUTHOR This dissertation has been submitted in partial tlilfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission. pro\ ided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the copyright holder. SIGNED: 4 ACKNOWLEDGEMENTS This dissertation would not have been possible without the ad\ ice. help, and support ot'manv indi\ iduals. 1 am especially appreciative of my committee members, all of whom provided valuable suggestions. ad\ ice. and encouragement. Special thanks to my ad\ isor. Dr. Robert Robichaux. whose passion for Hawaiian sih erswords is contagious! Rob's suggestions and attention to detail greatly improved this dissertation, and his incredible turnaround time as editor ensured that it was completed on time. Dr. Judie Bronstein, my unofficial co-advisor, provided valuable advice from the ver\' start of this project and in addition, generously provided a temporary home for me in her lab. I thank Drs. Lucinda .McDade and Molly Hunter for their comments on earlier drafts of these manuscripts, which greatl\- improv ed the quality of this dissertation. In addition to m> committee. Dr. Regis Ferriere provided much needed assistance in the de\ elopment and preliminar\ analysis of the siK ersword matrix model described in this stud> . I am also extremely grateful to many different people living and working in Hawaii, without whom this project would not have been possible. Much thanks to Dr. Lloyd Loope. of the L'SGS-BRD at Haleakala National Park, for his continual interest and support in this project. I am ver\- much indebted to him for his assistance with logistics and tlinding. as well as for his contribution of a long-term demographic data set that became a primarv' focus of this dissertation. Thanks also to Ron N'agata. for assistance with permits: Ellen Vangelder. fellow dog- and book-lover, for help with housing matters, as well as many excellent book recommendations; Forest and Kim Starr, for their boundless enthusiasm about all things botanical, and their endless dedication to the sih ersword monitoring project: and .A.rt Medeiros. natural historian extraordinaire, for his obser\ ations and insights. Thanks to m\- fellow graduate students - past and present - in the L'A Dept. of Ecology and E\ olutionar>' Biology, who ensured that my time at the Univ ersity of •Arizona was a stimulating and enjoyable experience. Special thanks to Jen Weeks. Cath\ Collins. Betsy .Arnold. Eileen Hebets. Margaret Evans. Asher Cutter. Dan Hahn. and Jessie Cable. 1 would also like to thank Clare Ellsworth and Jesus Garcia, two amazing undergraduates, who w ere a tremendous help in the field and lab. 1 am \ er>- gratefial for the endless support of family and friends: Fred and Geri ForsMh. Rachel Fors\th-Tuerck. Beck Freed. Michele Grzenda. Brandon Protas. Ste\ e •Anderson. Debbie Pearson. Jill .A\ er\-. .^nne Leyden. Janet ^'ang. Jeff Steinmetz and Kate Howe. Special thanks to my running gang - Kelly Goldsmith. Sue Clark. Doreen Castillo, and Debbie Nolen - for many tun fimes on the trail... This dissertation was primarily funded by a Graduate Research Fellowship from the National Science Foundation, and by Clairol. Inc.. through a grant from the National Parks Conserv ation .Association. .•Additional funding was provided by the .Arizona Flinn Foundation: the Department of Ecology and Ev olutionary Biology at The University of •Arizona: and the Research Training Grant in the .Analysis of Biological Diversification at The Univ ersity of •Arizona. I also received a year of financial support from the National Science Foundation through the GK-12 (CATTS) program at The University of •Arizona. DEDICATION Dedicated with Aloha to all those tirelessK' working to preser\ e Hawaii's beautiful places. ^'our passion and dedication are inspiring. 6 TABLE OF CONTENTS ABSTRACT 7 CHAPTER 1: INTRODUCTION 9 Population viahilin- analysis (Pl'A) C 'onscrvalion applications 11 This study 12 Explanation o f dissertation format 13 CHAPTER 2: PRESENT STUDY 15 REFERENCES 19 APPENDIX A: DENSITY-DEPENDENT SEED SET IN THE HALEAK.-\LA SILX ERSWORD (ARGYROXIFHIUMSASDWICESSE SSP. SL-iCROCEPHALUM): DEMONSTRATION OF AN ALLEE EFFECT 22 APPENDIX B: MEASURING PLANT REPRODUCTION FOR MATRIX MODEL ANALYSES 60 APPENDIX C: TEMPORAL AND SPATIAL VARIATION IN THE DEMOGRAPHY OF A THREATENED HAWAIIAN PLANT 1U3 APPENDIX D: DEMOGRAPHIC MODELING OF HAWAIIAN SILVERSWORDS (ASTER.ACEAE): IMPLICATIONS FOR CONSERVATION AND MANAGEMENT 215 ABSTR.\CT Population \ iability analyses based on matrix population models pro\ ide important information for species management. These analyses enable biologists to predict future population size and structure, assess extinction risk, and identify- the stages and transitions in a species" life history that ha\ e the largest etfects on population growth rate (/.). It is also possible, using these analyses, to weigh the relati\ e effectiveness of different management strategies. In this study. 1 constructed a matrix population model for a threatened Hawaiian plant species, the Haleakala sihersword (Argy roxiphiiim sandwicense ssp. macrocephalum). in order to assess the viability of this population under different disturbance and management regimes. 0\ er th e years. I assessed annual variation in seed set and quantified reproducti\ e \ ital rates for use in a matrix model. These data v\ ere combined with long-term demographic data in order to construct a stage-based matrix model for the Haleakala sih ersword. Using this model. 1 examined temporal and spatial \ ariation in silversword demography. 1 also used the model to exaluate management strategies for the Haleakala sih ersword and the related subspecies, the endangered .Mauna Kea sih ersword (Argyroxiphiiim sandwicense ssp. sandw icense). L sing deterministic and stochastic models. I compared the relativ e impacts of different threats on sih ersword persistence, and weighed the relativ e effectiv eness of different management options. s The Haleakala