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The electronic reconstruction of this document was made by Jon Sullivan, Chris Berry, and Lora Peacock (Lincoln University, Canterbury, New Zealand). 2 VEGETATION CHANGE IN TUSSOCK GRASSLANDS, WITH EMPHASIS ON HAWKWEEDS Record of a workshop of the New Zealand Ecological Society, Cass Field Station, Canterbury, 3-6 October 1991. Edited by G.G. Hunter, C.R. Mason and D.M. Robertson New Zealand Ecological Society Occasional Publication No.2 1992 ISSN 0114-8028 ISBN 0-9597949-2-1 Published by: The New Zealand Ecological Society (Inc.) P O Box 25178 Christchurch, New Zealand First published 1992 Suggested reference to articles in this volume: Author, 1992: Article title. In, Hunter, G.G.; C.R. Mason; D.M. Robertson (Editors), Vegetation change in tussock grasslands, with emphasis on hawkweeds, pp. xx-zz. Occasional Publication No.2, New Zealand Ecological Society, Christchurch. CONTENTS Preface v Editors' note vi List of participants vii Session One: Plant sociological issues Concepts and methods in assessing vegetation trends D.Scott 3 Inconsistencies between the scale of the hawkweed (Hieracium) M. Treskonova 12 problems and the methods used for investigating it Changes in grazed and retired fescue tussock grasslands, A.B. Rose, K.H. Platt and C. 13 Harper-Avoca catchment, Canterbury, 1965 - 1990 Frampton The influence of ground cover on hawkweed establishment in P.R. Espie 14 fescue tussock grassland A review of characteristics of mouse-ear hawkweed (Hieracium T.A. Jenkins 15 pilosella) Discussion Session One: 24 Session Two: Case studies from vegetation monitoring programmes Trends of mouse-ear hawkweed (Hieracium pilosella) in the J. Cuff 29 South Opuha catchment Effects of burning on Otago tussock grasslands ÖGlenshee K.B. Duuan 31 Station Hawkweeds in Otago - distribution, ecology and management N.S. Harris and A.F. Mark 32 Hawkweeds and vegetation monitoring in the Rabbit and Land K. Colhoun, B.D. Foran and 35 Management programme W.D. Ross Monitoring changes in non-forest ecosystems: case studies from K.J.M. Dickinson 39 Molesworth Station and the Mackenzie (Waitaki) basin Regeneration after fire on the Leibig Range, Mount Cook H. Wilson 44 National Park; the role of hawkweeds (Hieracium spp.) during the first 20 years A preliminary assessment of the effects of management on R.B. Allen, W.G. Lee and 45 mouse-ear hawkweed (Hieracium pilosella) establishment in A.F. Mark narrow-leaved snow tussock (Chionochloa rigida) grassland, Lammermoor Range, East Otago Time segment analysis of permanent quadrat data: changes in D. Scott 45 hawkweeds (Hieracium spp.) in the Waimakariri in 24 years1 King devil hawkweed (Hieracium praeallum) in wet, alpine, tall G.G. Hunter 50 tussock grassland, Hopkins Valley, South Canterbury' Session Two: Discussion 52 1 Paper not presented at workshop Session Three: Case studies from plant introduction, agronomic and grazing trials Hawkweed control and residual effects of oversowing, G.G. Cossens 57 overdrilling and herbicide in Otago Plant introduction trials in hawkweed communities on Galloway B.J. Wills, W.T. McDougall 59 Station, Upper Manorburn and J.S.C.Begg Long term climate records - can they assist real-time B.J. Wills, W.T. McDougall 62 management decisions in our tussock grasslands? and J.S.C. Begg A paddock based survey of management factors relating to B.D. Foran, J. Bates, P. 64 mouse-ear hawkweed (Hieracium pilosella) dominance in Murray, G. Heward and D. Central Otago Pickens Management effects on hawkweeds - the Stony Creek C.R. Mason 69 experience Response of mouse-ear hawkweed (Hieracium pilosella) in three D. Scott 71 long term manipulative agricultural trials Interaction between some pasture species and two hawkweed D. Scott and B.L. Sutherland 72 (Hieracium) speciesl Long term effects of pastoral management on improved tussock B.E. Allan and R.J. Doney 73 grassland vegetation Rabbit and sheep grazing in Mackenzie tussock grasslands: P.R. Espie and C. Meurk 74 vegetation change 1991 Studies of hawkweeds in the diet of sheep in New Zealand K.F. O'Connor and N. 75 tussock grasslands Covacevich Nutrient mass balances in pastoral high country K.F. O'Connor and P.S 76 Harris Session Three: Discussion 77 Session Four: Development of simple models relating hawkweed performance to environmental and management conditions A general model of past and likely future vegetation changes in A.B. Rose 81 grazed and retired tussock grasslands of the Harper-Avoca catchment, 700-1400 m altitude, 1200-1500 mm annual rainfall Temporal changes in the indigenous vegetation pattern of Otago, A.F. Mark 82 eastward from the lakes district Working group report: development of simple models of compiled by G.G. Hunter 85 hawkweed performance in tussock grasslands. Requirements for urgent research into hawkweed (Hieracium compiled by A.F. Mark 91 spp.) Annotated bibliography on hawkweeds (Hieracium spp.) compiled by D.Scott, T.A. 93 Jenkins and P.R. Espie 1 Paper not presented at workshop v PREFACE Hawkweeds (Hieracium spp.) are associated with a widely-acknowledged concern about degradation of tussock grasslands in the South Island. Resource managers, affected communities and scientists share concern for the future sustainability of tussock grassland based production and conservation systems. In 1990 a series of workshops and committees, convened by New Zealand Mountain Lands Institute, considered implications of the 'hawkweed problem' to land management and made recommendations for action. A clear outcome from these deliberations was that the status of hawkweeds was not widely understood in terms of the underlying interactions between vegetation, environment and management. It was recognised, however, that the findings of a substantial pool of research effort relating to these grasslands, when integrated in a 'hawkweed context', would increase our understanding and provide a more objective basis on which to evaluate the status of the grasslands and hence to formulate management strategies. Accordingly, in October 1991, the New Zealand Ecological Society convened a workshop to bring together people with key scientific information and understanding of hill and high country tussock grassland ecosystems to provide this integration. Participants included scientists and resource managers from Department of Conservation, DSIR, Forest Research Institute, High Country Section of Federated Farmers, Land Corporation Ltd., MAFTech, regional councils, Mountain Lands Institute and universities. Various scenarios regarding the role of hawkweeds have been put forward; the aggressive invader, the stress-tolerant indicator of long-term ecosystem decline, and the opportunist responding to shorter- term disturbances or stresses such as those related to climatic fluctuation (e.g., drought) and management effects (e.g., grazing). The challenge for this workshop was to critically evaluate available evidence and to advance best-bet explanations for the tussock grasslands change phenomenon. The measure of a successful workshop was seen as "what does available information tell us about what is happening in the tussock grasslands", rather than simply "what information do we have?" Aims of the workshop were: • To consider quantitative information on condition and trends in vegetation composition and cover in tussock grasslands, especially those containing hawkweeds. • To develop, as far as possible, simple models of trends in tussock grasslands, with emphasis on causes of change and the role of hawkweeds. • To improve understanding of the ecology of hawkweeds in tussock grasslands. • To identify future research requirements. • To identify management implications, from an ecological perspective. The initial papers at the workshop set the scene by outlining plant sociological issues in the tussock grasslands. The biology of mouse-ear hawkweed (Hieracium pilosella) was reviewed. Case-studies set out the evidence of vegetation change and vegetation-environment-management