Heard Island, a Case Study
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BRYOPHYTE DIVERSITY AND TERRESTRIAL PLANT ECOLOGY IN THE SUBANTARCTIC : HEARD ISLAND, A CASE STUDY Dana Michelle Bergstrom B.Sc. M.Sc. A thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy. February, 1993. School of Biological Sciences, Macquarie University. MACQUARIE UNIVERSITY HIGHER DEGREE THESIS (PhD) AUTHOR’S CONSENT This is to certify that I, being a candidate for the degree of Doctor of Philosophy am aware of the policy of the University relating to the retention and use of higher degree theses as contained in the University’s PhD Regulations generally, and in particular, Regulation 21(2). In the light of this policy and the provisions of the above Regulations, I agree to allow a copy of my thesis to be deposited in the University Library for consultation, loan and photocopying forthwith. \............ Z?5:^ ^ “Tr /Signature of Witness Signature of Candidate Dated t h i s .......................oL ... day of . 19 3 The Academic Senate on 10 August 1993 resolved that the candidate had satisfied requirements for admission to this degree. This thesis represents a major part of the prescribed program of study. Certificate of originality I hereby declare that the data and information in this thesis have not been submitted elsewhere for any other degree. Except where expressly acknowledged to the contrary in the text or acknowledgements all the work is my own. Dana Michelle Bergstrom Contents CONTENTS ABSTRACT ACKNOWLEDGMENTS CHAPTER 1 Introduction and description of environments 1.1 Introduction to the Subantarctic Zone and to this project............................................................................... ...1 1.1.1 Subantarctic Zone................................................................................................................................. ...1 1.1.2 Introduction to the project.................................................................................................................. ...3 1.2 Heard Island 1.2.1 Geology, origin and physiography..................................................................................................... ...4 1.2.2 Climate.................................................................................................................................................. ...9 1.2.3 Past and present vegetation of Heard Island...................................................................................... .10 1.2.4 Fauna .................................................................................................................................................... .19 1.3 Marion and Prince Edward Island. 1.3.1 Geology, origin and physiography...................................................................................................... .20 1.3.2 Climate ................................................................................................................................................ .20 1.3.3 Vegetation.............................................................................................................................................. .21 1.4 Macquarie Island 1.4.1 Geology, origin and physiography...................................................................................................... .22 1.4.2 Clim ate.................................................................................................................................................. .23 1.4.3 Vegetation............................................................................................................................................. .23 1.5 Comparison of Heard Island physical environments with Marion and Prince Edward Islands, and other subantarctic islands........................................................................ .25 1.6 Summary .................................................................................................................................................... .28 CHAPTER TWO Vegetation survey methods 2.1 General survey details........................................................................................................................................... ,30 CHAPTER THREE The bryoflora of Heard Island: revised checklist, annotations and phytogeographical considerations. 3.1 Introduction .................................................................................................................................................... .33 3.2 Collections .................................................................................................................................................. ,34 3.3 Annotated species list of bryophyte taxa recorded from Heard Island 3.3.1 Mosses.................................................................................................................................................... ,34 3.3.2 Liverworts............................................................................................................................................... 38 3.3.3 Summary Notes on Clifford’s 1953 checklist..................................................................................... 39 3.4 Discussion 3.4.1 Phytogeography..................................................................................................................................... 39 3.4.2 Size of Flora............................................................................................................................................ 42 3.5 Summary .................................................................................................................................................... 42 CHAPTER FOUR Distribution of bryophytes on Heard Island 4.1 Introduction .................................................................................................................................................... 44 4.2 Methods 4.2.1 Analysis of distribution..................................................................................................................... 45 4.3 Distribution and Diversity........................................................................................................................ 45 4.4 Summary ................................................................................................................................................. 47 Contents CHAPTER FIVE The diversity of bryophytes within Heard Island vegetation units 5.1 Introduction ...................................................................................................................................................... 48 5.2 Bryophytes in Hughes' (1987) vascular plant categories..................................................................................... 49 5.3 Ordination and classification analyses 5.3.1 TWINSPAN Classification analysis.......................................................................................................50 5.3.2 DECORANA analysis.............................................................................................................................54 5.4 Details of ecological groups.................................................................................................................................. 57 5.5 Discussion ...................................................................................................................................................... 65 5.6 Summary ...................................................................................................................................................... 66 CHAPTER SIX Vegetation patterning in feldmark on Heard Island and other subantarctic islands 6.1 Introduction ...................................................................................................................................................... 69 6.2 Heard Island sites 6.2.1 Macey Cone, Laurens Peninsula............................................................................................................. 70 6.2.2 Dovers Moraine, Spit Bay....................................................................................................................... 74 6.3 Marion and Prince Edward Islands sites 6.3.1 Kaalkopie lava flow, Marion Island........................................................................................................78 6.3.2 Kent Crater, Prince Edward Island.........................................................................................................80 6.4 Discussion of patterning and establishment of hypothesis 6.4.1 Discussion..................................................................................................................................................82 6.4.2 Hypothesis.................................................................................................................................................83 6.5 Testing the hypothesis on Macquarie Island 6.5.1 Feldmark on Macquarie Island................................................................................................................84 6.5.2 Sites ...................................................................................................................................................... 84 6.5.3 Propagule germination trials....................................................................................................................87 6.5.4 Surface movement.....................................................................................................................................89