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Rarity and Commonness of New Zealand Ferns A Dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science, Honours, in Conservation and Ecology at Lincoln University by Catherine Frances Mountier Lincoln University 2014 Abstract of a Dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science, Honours, in Conservation and Ecology Abstract Rarity and Commonness of New Zealand Ferns by Catherine Frances Mountier A macroecological approach was used to look for patterns in, and correlates of, rarity and commonness in the New Zealand fern flora, which is comprised of 250 species. Herbarium records and expert knowledge were used to map fern species distributions from which range sizes were calculated, and used as a measure of rarity and commonness. Fern species frequency distributions showed a pattern of many small and fewer large range sizes, with bimodal peaks at very small and medium range sizes. Latitudinal differences in range sizes showed evidence of a geometric constraint and the mid-domain effect, and did not directly support Rapoport’s Rule which suggests larger range sizes at higher latitudes and vice versa. Trait data for each fern species, including morphological characteristics, were compiled from the literature, as were habitat preferences, elevational range, and biostatus,. Both univariate and multivariate linear mixed models were used to determine relationships between species traits and range sizes for 211 fern species for which data were available. Habitat specialists had smaller range sizes than generalists, and species occurring in forest and/or montane environments had larger range sizes than those that did not, as did epiphytic species. The variation in range size explained by phylogeny (taxonomic family and genus) was lower than that explained by traits. Patterns of rarity and commonness differed markedly between indigenous and introduced species. This study provides new knowledge of patterns in the diversity of the New Zealand fern flora. ii Keywords: Ferns, rarity, range size, linear mixed models, Rapoport’s Rule, mid-domain effect, endemism, biostatus, New Zealand. Acknowledgements Many thanks to my supervisor Hannah Buckley, and Brad Case for the GIS component. Thanks to Leon Perrie and Patrick Brownsey at Te Papa for checking and correcting fern species distributions, and advice on numerous details of this study. The herbaria at Te Papa, the Auckland War Memorial Museum and the Allan Herbarium at Landcare Research provided herbarium records for fern species which form the basis of the spatial data in this study. Marian Dassonneville and Anais Tieche extracted and entered some of the fern trait data. Lincoln University and the Freemasons for financially supported my studies this year. Thanks to my fellow students for camaraderie and mutual support, and special thanks to Phil Holland and Jane Mountier for helping me achieve this goal. iii Table of Contents Abstract ....................................................................................................................................... ii Table of Contents ........................................................................................................................ iv List of Tables ............................................................................................................................... vi List of Figures ............................................................................................................................. vii Chapter 1 Introduction ............................................................................................................ 1 1.1 Background ...............................................................................................................................1 1.2 What is Rarity? ..........................................................................................................................2 1.3 Causes of rarity and commonness ............................................................................................5 1.3.1 Environmental factors .................................................................................................. 6 1.3.2 Colonisation ability ....................................................................................................... 6 1.3.3 Body size ...................................................................................................................... 8 1.3.4 Historical constraints ................................................................................................... 8 1.4 Biology, ecology, rarity and commonness of ferns ................................................................ 10 1.5 New Zealand ferns ................................................................................................................. 12 1.6 Aims and Objectives ............................................................................................................... 14 1.6.1 Research questions: ...................................................................................................14 1.6.2 Specific objectives: .....................................................................................................14 Chapter 2 Methods .................................................................................................................15 2.1 Data collection ....................................................................................................................... 15 2.1.1 Herbarium data ..........................................................................................................15 2.1.2 Spatial data.................................................................................................................15 2.1.3 Range sizes .................................................................................................................16 2.1.4 Trait and attribute data ..............................................................................................17 2.2 Data Analyses ......................................................................................................................... 21 Chapter 3 Results ....................................................................................................................28 3.1 Descriptive statistics .............................................................................................................. 28 3.1.1 Measures of range size ..............................................................................................28 3.1.2 Range size frequency distribution graphs ..................................................................31 3.2 Statistical models ................................................................................................................... 35 3.2.1 Univariate models ......................................................................................................35 3.2.2 Multivariate Models ...................................................................................................46 Chapter 4 Discussion ...............................................................................................................53 4.1 Limitations of the research .................................................................................................... 57 4.2 Further study.......................................................................................................................... 57 4.3 Implications and applications for biodiversity conservation ................................................ 58 Chapter 5 Conclusion ..............................................................................................................59 iv Appendix A GIS .......................................................................................................................60 A.1 Examples of GIS maps for one fern species, Abrodictyum elongatum, showing herbarium specimen location points, and the ecological districts map derived from that, from which range size area was calculated. ............................................................................................. 60 A.2 Example of a GIS model constructed to automate process of calculating range sizes. ........ 60 Appendix B Range Sizes ..........................................................................................................61 B.1 Ranked range sizes of 241 New Zealand fern species (see next page). ................................. 61 Appendix C Fern Species List ................................................................................................. 64 C.1 List of New Zealand fern species for which data was compiled. e=endemic, n=native and i=introduced. Lower sections show species classed as “casuals”, and species which occur only on outlying islands and are