Underpinnings of fire management for biodiversity conservation in reserves A. Malcolm Gill Fire and adaptive management report no. 73 Underpinnings of fire management for biodiversity conservation in reserves Fire and adaptive management report no. 73 A. Malcolm Gill CSIRO Plant Industry, GPO Box 1600, Canberra, ACT 2601 Fenner School of Environment and Society, The Australian National University, Canberra, ACT 0200 Bushfire Cooperative Research Centre, Albert St, East Melbourne, Vic 3002 Underpinnings of fire management for biodiversity conservation in reserves Published by the Victorian Government Department of Sustainability and Environment Melbourne, November 2008 © The State of Victoria Department of Sustainability and Environment 2008 This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968. Authorised by the Victorian Government, 8 Nicholson Street, East Melbourne. Printed by Stream Solutions Printed on 100% Recycled paper ISBN: 978-1-74208-868-6 (print); ISBN: 978-1-74208-869-3 (online) For more information contact the DSE Customer Service Centre 136 186 Disclaimer This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Cover photograph: Malcolm Gill Acknowledgements This contribution was initially inspired by senior officers of the Victorian Department of Sustainability and Environment (DSE) – especially Mike Leonard. His encouragement, and that of Gary Morgan and Dr Kevin Tolhurst (University of Melbourne, Victoria), is greatly appreciated. Facilitation of this project by Francis Hines and Liam Fogarty is gratefully acknowledged. Liam Fogarty, Gordon Friend and Andrew Wilson, all of DSE, provided many useful suggestions after scrutinising the draft manuscript. Angie Kelly kindly assisted with editorial matters. For generously assisting in providing various details for Chapter 2, I would especially like to thank Ian Dicker, New South Wales National Parks and Wildlife Service, and also Nick Lhuede (Rural Fire Service, ACT), Simon Hemer and Liam Fogarty (formerly of the Department of Urban Services, ACT), Leigh Miller (Country Fire Service, South Australia), Dave Broderick (ACT Bush Fire Council, ACT Volunteer Brigades Association and formerly a volunteer with the Country Fire Authority of Victoria), Mike Leonard (formerly DSE) and Nick Ryan (DSE). Ian Dicker generously read and commented on this chapter. Dr Ian Lunt of Charles Sturt University made constructive and detailed comments on Chapter 4, which were much appreciated. Discussions with Dr Joe Walker and David McKenzie on the grazing issue were also valuable. For reading the entire manuscript and offering helpful suggestions, I would like to thank Dr Simon Heemstra, New South Wales Rural Fire Service and Dr Mick Brown. The assistance of Dr Jon Marsden-Smedley, Dr Jeremy Russel-Smith, Dr Peter F Moore and Mike Wouters for reviewing and commenting on a number of chapters is also greatly appreciated. In a general sense, I would like to thank Professors Peter Kanowski and Brendan Mackey for my appointment as a Visiting Fellow at the School of Resources, Environment and Society, The Australian National University (ANU) – now the Fenner School of Environment and Society. Similarly, I am grateful to CSIRO Plant Industry through the Chief, Dr Jeremy Burdon, and Program Leader, Dr Andrew Young, for supporting me as an Honorary Research Fellow. For great encouragement and constructive debate over years or decades, I would like to acknowledge Professor Ross Bradstock (University of Wollongong), Dr Geoff Cary (ANU), Dr Karen King (ANU) and Dr Rod Weber (University of New South Wales) – my colleagues in the Landscape Fire Ecology Group at ANU and Project B1.2 of the Bushfire CRC. As always, Beverly has had a strong and helpful supporting role in my work. This publication has been produced with the support of the Commonwealth Natural Disaster Mitigation Program as part of the DSE’s Learning by Doing Project. Fire and adaptive management Fire ii Contents Acknowledgements . ii Preface . vi Foreword . viii Chapter 1 Introduction . .2 Management in brief . 2 The management process . 3 Fire management – especially fire suppression. 6 Text Box 1.1. Spot fires. 8 Summary . 10 Chapter 2 Track networks, fire suppression and the environment . 1. 2 Introduction. 12 Track types. 12 Effects of tracks on the environment. 14 Track width: how wide should tracks be?. 17 Track density: how much track is enough? . 23 Model track networks: access all areas? . 25 and adaptive management Fire Sizes and shapes of areas delimited by track networks . 30 A track-free or minimal-track reserve. 32 Discussion . 36 Conclusion. 39 Chapter 3 Prescribed burning as a fuel-modification measure . 42 Introduction. 42 Text Box 3.1. Prescribed burning. .43 Fuel, vegetation and habitat . 44 Fuels for prescribed burning. 46 Effectiveness of prescribed burning for fuel modification. .47 Assessing the effects of burning on fuel . .48 Assessing the effectiveness of fuel reduction for fire suppression. .50 Effects of fires on the environment . .51 Text Box 3.2 Literature on the effects of fire regimes . 55 Conclusion. 55 iii Underpinnings of fire management for biodiversity conservation in reserves Chapter 4 Fuel modification by grazing or browsing . .58 Introduction. 58 Environmental effects of grazing. .60 Grazing regimes. 64 Conservation under grazing and burning regimes . 67 Discussion and conclusion. 68 Chapter 5 Between-fire intervals, times since fire and variations in both . .72 Introduction. 72 Regular or random: a simple model. .75 Effects of a fixed-minimum interval. .81 General theory for between-fire interval and time-since-fire distribution with a given fire-free interval. .86 Discussion and conclusion. 91 Chapter 5a Probability of burning at a point in relation to time since fire and between-fire interval . 9. 2 Probability of burning taking place at a point in the landscape . 92 Heterogeneity within landscapes. .93 Chapter 6 Fire intervals in practice: which mean, what variation? . .96 Introduction. 96 Fire intervals before white settlement. 96 Intervals based on recent post-settlement history . 97 Intervals based on plant species’ characteristics: some background. 99 Choosing a between-fire interval: fuels and plant species. 102 Animal species as indicators . 108 Using contemporary fire histories . 110 Text Box 6.1. Conservation of Athrotaxis selaginoides, an endemic Tasmanian conifer: a case history. .112 Discussion and conclusion. .113 Fire and adaptive management Fire iv Underpinnings of fire management for biodiversity conservation in reserves Chapter 7 Mosaics for conservation and fire control . 11. 6 Text Box 7.1. The nomenclature of patchiness of fires. 117 Fire-created mosaics and the conservation of biodiversity . 118 Time-since-fire mosaics and fire-spread mitigation. .121 Discussion and conclusion. .125 Chapter 8 Summary: Fire management for biodiversity conserva- tion in reserves . .128 References . .132 List of reports in this series . 150 Fire and adaptive management Fire v Preface Nowhere in Australia are bushfire matters more contentious than in south-eastern Australia, where the twin tragedies of the destruction of economic assets and the loss of human life are graphically presented by the media, along with dramatic pictures of high intensity fires. What should be done about such fires? Media reports implicitly highlight the question, ‘What are our assets?’ Human life and property are major societal assets. Pastures and stock are rural assets. Native plants and animals, catchments and infrastructure are also assets. Some assets are affected by one event – houses, human lives, trees and individual animals – others by a sequence of fires, especially species of plants and animals. Thus fires affect a diverse array of natural and societal assets, individually and collectively. Topics within the discipline of bushfire science and management are numerous and complex. If the knowledge needed for making informed decisions had already been acquired, and if the conceptual understanding necessary for informed application of knowledge had already been gained, then matters of contention would appear to be readily resolved. However, there is still much to learn and the debate involves wider matters, such as: government priorities and budgets; what different groups in our society consider to be assets (a reflection of their values); the methods and speed of fire suppression; land-use planning; the nature and speed of recovery after major events; and how landscapes and their components respond to fires. Responses by authorities and landowners to these issues usually involve intervention in the landscape, through fire suppression and fuel manipulation. These are inextricably linked with the land use being considered. A farmer’s approach to fuel management is likely to be quite different to that of a conservation manager, or that of an urban-interface dweller, because of the differences in assets being considered and the resources available to them. Given that the range of bushfire issues is so large, no short publication such as this can address all of them. Here, the purpose is to present and explain some of the ideas