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Durham E-Theses Aspects of the ecology of the Lepidoptera associated with Calluna vulgaris on managed northern heath Haysom, Karen A. How to cite: Haysom, Karen A. (1994) Aspects of the ecology of the Lepidoptera associated with Calluna vulgaris on managed northern heath, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/5597/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 Aspects of the Ecology of the Lepidoptera Associated with Calluna vulgaris on Managed Northern Heath by Karen Haysom B.Sc. (Dunelm) The copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. A thesis presented in candidature for the degree of Doctor of Philosophy Department of Biological Sciences University of Durham 1994 I certify that all material in this thesis which is not my own has been identified and that no material is included for which a degree has previously been conferred on me. The copyright of this thesis rests with the author. No quotation from it should be published without her prior written consent and information derived from it should be acknowledged. Ill Abstract Aspects of the ecology of the Lepidoptera associated with Calluna vulgaris on managed northern heaths were studied between 1991-1993 at five study areas in Durham, Northumberiand and southern Scotland. The study areas were northern heaths that were managed by rotational burning and each comprised a mosaic of even-aged Calluna stands. Lepidoptera were studied in the larval stage of development. A range of even-aged Calluna stands, with different ages and vegetation structures were selected as sample sites and the larval assemblages in the different stands were monitored by sweepnet sampling. A total of 29 species of macrolepidoptera and 3 species of microlepidoptera larvae were recorded. Species lists were similar at the five study areas, but the relative abundance of individual species varied between sites. The degree of similarity between communities was not related to the distance between study areas. The densities of many macrolepidoptera species were closely correlated with Calluna height. Intercorrelation between vegetation architecture variables meant that other factors e.g. green shoot density or flower density could also have been responsible. Lepidoptera diversity varied with Calluna height, due to changes in the dominance of common species and the presence of additional rare species at certain heights. However patterns in diversity were not consistent between study areas. The concentrations of total leaf nitrogen, total phenolics and water were significantly higher in current year's Calluna leaves than in the shoots formed in previous years. In same-aged leaves, there was no relationship between plant age and the concentrations of leaf nitrogen or phenolics. The water content of same-aged leaves was negatively correlated with stand age at some sites and at certain sampling times. Larvae offered different choices of ericaceous plants exhibited significant preferences for different plant species and also for the current year's Calluna leaves rather than previous years' growth. Mechanisms that could be responsible for the observed distribution patterns of larvae in different heights of Calluna are discussed. The maintenance of a mosaic of different-aged Calluna stands on northern heath represents the best conservation strategy for Lepidoptera by maintaining species diversity at a site. IV Acknowledgements I would like to thank Dr John Coulson and Dr Val Standen of Durham University and Mr Angus MacDonald of Scottish Natural Heritage for providing help and encouragement while supervising this study. N.E.R.C. and Scottish Natural Heritage financed the work through a Case Research Studentship and Professor P.R. Evans provided facilities in the Department of Biological Sciences. Access to study areas was provided by Lambton Estates, Langholm Estates, Lord Crewe Estates, Mr D. Knowles, Miss Little, Mr Elliot and Mr S. Scott. 1 would like to thank the gamekeepers and farmers on these areas for their support, especially Andy Walker, Dennis Dodds, Mr and Mrs Colclough and Brian Mitchell. Chris Baddenoch, Robin, Reuben and the rest of the Scottish Natural Heritage office at Galashiels gave invaluable assistance in Scotland by finding suitable study areas, arranging contact and access with landowners, giving information on S.S.S.I.'s and providing accommodation and hospitality on my visits to the borders. Steve Redpath's research team provided hospitality and a bed at Langholm-Newcastleton Hills S.S.S.I. Gerry Haggett identified various macrolepidoptera larvae, Mr T.C. Dunn the microlepidoptera adults and Andy Buckham some macrolepidoptera adults. All three were very generous with their time and shared their enthusiasm for Lepidoptera with me. Dr Susan Hartley of LT.E., Banchory taught me the chemical analysis techniques used in Chapter Seven, and with Jim Kerslake, showed me their winter moth study areas. I am grateful to both Sue and Jim for advice and correspondence. Dr Alan Pearson provided laboratory facilities, equipment and advice for chemical analysis work in Durham. The comparison of the extraction efficiencies of the Blow-Vac and D-Vac suction techniques (section 4.4.4) was in collaboration with Iain Downie. 1 would like to thank Susan Haysom, David Wood, Iain Downie, Mathew Parsons, Jane Borthwick, Andy Hoodless, Rob Evans, Chris Tapp and Eric Henderson, for lending a hand with fieldwork and enduring rain, snow and point quadrats. Eric Henderson gave much help with technical problems. Cathy Thompson, Gilbert Roberts, Iain Downie and Chris Tapp gave advice on computing. For advice on other aspects of the study and general discussions I am grateful to Brian Eversham, Lewis Davies, Phil Hulme, Ann Smithson and Carol Fielding. I thank Susan Raven, David Wood and Ken Durose for their help during the final days of this thesis and Monica Calado, Rachel Koktava, Gary Wheelhouse, Susan Haysom, Ann Smithson, Steve Palmer, Penny Andrews, Mathew Parsons, Simon Lawrence, Tom Hibbert, Jon Booker and Rebecca Godsell for general encouragement. VI Table of Contents Abstract "i Acknowledgements iv Table of Contents vi Chapter 1 Introduction 1 Chapter 2 The Study Areas and Sample Sites 9 2.1 The study areas 9 2.1.1 Waskerley Moor, near Edmundbyers, County Durham 10 2.1.2 Winnowshill Farm, near Slaley, Northumberland 10 2.1.3 Stuartfield Lodge, near West Butsfield, County Durham 10 2.1.4 Greenlaw Moor S.S.S.I., Berwickshire 11 2.1.5 Langholm-Newcastleton Hills S .8.8.1., Roxburghshire 11 2.2 Sample sites 11 Chapter 3 The Vegetation at the Study Areas 13 3.1 Introduction 13 3.2 Methods 14 3.2.1 The study areas 14 3.2.2 Height of Calluna stands 14 3.2.3 Density of plant structures 15 3.2.4 Flori Stic composition 15 3.2.5 Age of Calluna stands 16 3.2.6 Statistical analyses 16 3.3 Results 16 3.3.1 The relationship between stand age and stand height 16 vn 3.3.2 The relationship between stand age and density of Calluna parts 17 3.3.3 The relationship between stand height and density of Calluna parts 17 3.3.4 The relationship between the densities of green shoots and flowers 22 3.3.5 Floristic composition 22 3.4 Discussion 27 3.4.1 Age and height as descriptions of stand vegetation 27 3.4.2 Variation in the density of Calluna green shoots 28 3.4.3 Variation in the density of Calluna flowers 29 3.4.4 Development of Calluna cover 29 3.4.5 The relationship between Calluna height, green shoot density and other species 29 3.4.6 The flora at the study areas 30 3.4.7 Evaluation of methodologies 30 Chapter 4 Methods of Sampling Lepidoptera Larvae 31 4.1 Introduction 31 4.2 The identification of Lepidoptera larvae 31 4.3 Description of the methods used to sample Lepidoptera larvae 32 4.3.1 Two-stage sampling method 32 4.3.2 Sampling with a sweep net 34 4.3.3 Direct searching 34 4.3.4 Blow-Vac 35 4.3.5 D-Vac 35 4.4 Evaluation of Methods 35 4.4.1 A comparison of sweepnet sampling with jarring followed by extraction in Berlese-Tullgren funnels 36 via 4.4.2 Calibration of sweepnet data against data collected by the two-stage jarring and Berlese-Tullgren extraction technique 43 4.4.3 The efficiency of Berlese-Tullgren extraction with different species of Lepidoptera larvae 52 4.4.4 The efficiency of the Blow-Vac and D-Vac suction methods for the extraction of Lepidoptera larvae 56 4.5 Discussion 58 Chapter 5 An Introduction to the Lepidoptera Larvae Found During the Study 62 5.1 Introduction 62 5.2 Sampling regime 62 5.2.1 Durham and Northumberland study areas 62 5.2.2 Scottish study areas 63 5.3 The Lepidoptera species found during the study 63 5.3.1 Methods 63 5.3.2 Results ; 63 5.4 The composition of the Lepidoptera larvae community at different study areas