Canopy Arthropods and Herbivory on the Tasmanian Southern Beeches, Nothofagus cunninghamii and Nothofagus gunnii Volume 1 P. Jane Keble-Williams MB.ChB. (University of Sheffield, UK) Grad. Dip. Env. Stud. (University of Tasmania) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy School of Geography and Environmental Studies University of Tasmania March 2012 ii DECLARATION This thesis contains no material which has been accepted for a degree or diploma by the University or any other institution, except by way of background information and duly acknowledged in the thesis, and to the best of the my knowledge and belief no material previously published or written by another person except where due acknowledgement is made in the text of the thesis, nor does the thesis contain any material that infringes copyright. P.J. Keble-Williams Statement of Authority of Access This thesis may be made available for loan and limited copying and communication in accordance with the Copyright Act 1968. iii iv ABSTRACT The Gondwanan relict tree genus Nothofagus has generated much research due to its biogeographical significance in understanding the biota of the Southern Temperate Zone. However, the southern temperate forest arthropod fauna, including that of Nothofagus, has received less attention than northern temperate forest and tropical rainforest. The extant Tasmanian Nothofagus canopy arthropod fauna has been considered depauparate. Yet with a palaeohistory of long persistence, high diversity and widespread distribution of the genus within Australia, the endemic Tasmanian Nothofagaceae – the evergreen Nothofagus cunninghamii and winter deciduous N. gunnii - could be expected to have accreted a large and diverse arthropod fauna, as have its sister Fagalean families in the northern hemisphere. Conversely, range contraction of Tasmanian Nothofagus in the increasingly arid conditions of the late Tertiary, and its cyclical isolation from the Australian mainland during the glacial cycles of the Pleistocene, could have depleted the associated arthropod fauna. Thus the aims of this project were to document in detail the diversity and structure of the invertebrate communities associated with both species of Tasmanian Nothofagus; to build an inventory of canopy arthropod fauna according to feeding guild; and to measure the levels of herbivory, as an indication of herbivore activity, on the these host species. These data enabled comparison of the arthropod communities on the two hostplants, and comparison with similar studies on closely related tree species (Nothofagus elsewhere, northern temperate Fagales) and other Australian tree taxa, now widespread (Acacia and Eucalyptus). A cross section of survey sites was chosen, 17 for N. cunninghamii, and 12 for N. gunnii, including three where the host plants were sympatric. Canopy arthropods were sampled by branch beating, and leaves were collected from, or examined in situ on marked branches. The sampling schedule from March 1998 until March 2002 yielded data sets by Nothofagus species, site, sampling aspect, season, region, and between years. Priority was given to arthropod orders containing herbivorous taxa or scavenging taxa known to forage on trees. These were sorted to family, then genus and species where possible, otherwise to morphospecies; and allocated to feeding v guilds. The leaves were designated ‘chewed’ or ‘intact’ and the leaf area lost from the chewed leaves was estimated. Mean percentage leaf area loss was calculated as a measure of herbivory. The main finding from these investigations was that there existed a strong contrast in the diversity and taxonomic profile of the arthropod fauna between the two Nothofagus species. For N. cunninghamii, the associated fauna was relatively rich in taxa and comparable with other temperate zone trees in both its diversity and guild structure. Similarly the N. cunninghamii herbivory levels were within the range of those found on temperate and subtropical tree taxa. N. gunnii in contrast was clearly depauparate, particularly lacking many important folivorous groups such as chrysomelid beetles, leaf miners and aphids. However there was, for the two Nothofagus species, considerable local variation in the arthropod communities and levels of herbivory - between regions; between sites within a region; and within a site, seasonal variation and also differences between consecutive sampling years - insights which have significance for effective biodiversity surveys and conservation strategies. vi ACKNOWLEDGEMENTS I owe many thanks to my supervisor, Dr Peter McQuillan, for his enthusiasm for the project, and for his patient encouragement, help and advice throughout its course. For their help in identifying specimens, thanks are due to: Dr Murray Fletcher, Orange Agricultural Institute, Orange, NSW (Hemiptera, Auchenorrhyncha); David Green, School of Geography and Environmental Studies, University of Tasmania, Hobart (Acarina); Dr Penny Gullan & Nate Hardy, UC Davis, CA (Hemiptera, Coccoidea, Eriococcidae); Dr Peter McQuillan, School of Geography and Environmental Studies, University of Tasmania, Hobart (Lepidoptera, Coleoptera); Dr Laurence Mound, CSIRO Entomology, Canberra (Thysanoptera) Dr Cathy Young, Tasmanian Museum and Art Gallery, Hobart (Lepidoptera, Geometridae). Thankyou to Associate Professor Noel Davies, Central Science Laboratory, University of Tasmania, for his expertise in extracting leaf chemicals and waxes and for interpretation of the resulting spectra. For technical help, thanks go to: Dennis Charlesworth, lab technician; David Green, electron microscope work; Mick Russell, mapping data; and Douglas Nichols, database design and field assistance at the Western and Central sites. Within the School of Geography and Environmental Studies, I gratefully acknowledge successive Heads of School, Graduate Research Coordinators and Administrative Staff, for their understanding and forbearance with my long breaks from candidature to deal with various life events. And of course, many thanks to colleagues from the fifth floor, the lab, and the tearoom, for their warm camaraderie. Outside academia, I thank friends from the Salamanca Rotary Club for their interest and support, and for the lively banter and repartee at the Tuesday breakfast meetings – a fillip for the week. Hefyd, diolch yn fawr iawn Mary, Betty a Peter B. Finally, this somewhat protracted project was possible thanks to support and encouragement from my late father, Dr Gwilym Keble-Williams, retired GP, wood- turner, sailor, Rotarian, and latterly cheerful field assistant on his visits to Tasmania from Wales. He possessed an unquenchable and infectious sense of humour, insatiable curiosity and zest for life. vii viii ‘Without curiosity, without a passion for discovery, nature cannot endure. And without nature, curiosity will fade … I cannot help feeling that, ultimately, curiosity will be sustained. It is so fundamentally human to thirst for knowledge and to turn to nature for visions of the unknown.’ Thomas Eisner, 2003, For the Love of Insects, p.404. ix x TABLE OF CONTENTS Declaration ........................................................................................................iiiError! Bookmark not defined. Abstract .........................................................................................................v Acknowledgements............................................................................................viiError! Bookmark not defined. Table of Contents...............................................................................................xi List of Tables and Figures..................................................................................xvii Chapter 1 Introduction .......................................................................................1 1.1 Research Rationale................................................................................... 2 1.2 Research Questions.................................................................................. 3 1.3 Research Approach .................................................................................. 3 1.4 Thesis Outline.......................................................................................... 5 Chapter 2 Nothofagus ........................................................................................6 2.1 Nothofagus, Fagus and the Order Fagales................................................. 6 2.2 Biogeography And Palaeohistory ............................................................. 9 2.2.1 Plate Tectonics and the demise of Gondwana........................................... 10 2.2.2 Nothofagus Lineage: Origins, Palynology, Phylogeny and Cladistics ....... 11 2.2.3 Vicariance or Dispersal? .......................................................................... 18 2.2.4 Palaeoecology of Nothofagus in Australia ................................................ 20 2.3 Nothofagus in Tasmania........................................................................... 24 2.3.1 Palaeohistory ........................................................................................... 25 2.3.2 Distribution and Floristic Associations..................................................... 28 2.3.3 Climate Profiles and Adaptations ............................................................. 31 2.4 Nothofagus and its Arthropods: Evolutionary History .............................. 32 xi Chapter 3 Canopy Arthropods and Herbivory.....................................................35