CRC for Australian Weed Management #11 Technical Series Impact of weeds on threatened biodiversity in New South Wales Technical Series #11 • Impact of weeds on threatened biodiversity in New South Wales Series #11 • Impact of weeds on threatened Technical Aaron Coutts-Smith and Paul Downey Pest Management Unit, Parks and Wildlife Division Department of Environment and Conservation (NSW) Acknowledgments The authors thank the Royal Botanic Gardens Trust (BGT) for kindly supplying distribution data on native plants and weeds in New South Wales (NSW) and the NSW Department of Environment and Conservation (DEC) for allowing access to internal data sets, listings of NSW threatened species and to the determinations of the NSW Scientific Committee. The authors also thank: Shaan Gresser (DEC) for compiling the initial data set and for entering a large proportion of the data; Mike Saxon (DEC) for providing access to profiles of the NSW threatened species prior to their public release; Gary Chapple (BGT) for assistance in acquiring data and ascribing the data to the 13 Natural Resource Management regions in New South Wales; and to Paul Mahon (DEC) for input to the development of the threat hierarchy. Many individuals provided assistance throughout the project, for which the authors are grateful, including the following DEC staff: Hillary Cherry, James Dawson, Andrew Leys, Kylie McClelland, Chris Togher and Graham Wilson, and from the CRC for Australian Weed Management (Weeds CRC) Kelly Scott, Sally Vidler and Rita Reitano. Financial assistance for this project was provided by the Weeds CRC and the DEC, without which this project could not have been completed. The authors also thank the Weeds CRC for publishing the report as part of their Technical Series. Finally, the authors thank Dr Rachel McFadyen (Weeds CRC) and Dr Tony Grice (CSIRO) for advice on structure and content of the report. In addition, we thank Dr Grice for providing comments on earlier versions of the report and Dr Richard Groves (CSIRO) and Dr Scott King (DEC) for reviewing the manuscript prior to publication and Catherine Munro for editorial advice. Impact of weeds on threatened biodiversity in New South Wales Impact of weeds on threatened CRC for Australian Weed Management Technical Series no. 11 August 2006 Copyright © CRC for Australian Weed Management 2006 This book is copyright. Except as permitted under the Australian Copyright Act 1968 (Commonwealth) and subsequent amendments, no part of this publication may be reproduced, stored or transmitted in any form or by any means, electronic or otherwise, without the specific written permission of the copyright owner. Enquiries and additional copies: CRC for Australian Weed Management, Waite Campus, University of Adelaide, PMB 1, Glen Osmond, SA 5064 Australia Telephone: (61) (08) 8303 6590 Fax: (61) (08) 8303 7311 Email: [email protected] www.weeds.crc.org.au ISBN 1-920932-56-9 Front cover: Blackberry infestation at Pound Creek near Tumbarumba, NSW. Photo: CSIRO Entomology This report should be cited as: Coutts-Smith, A.J. and Downey, P.O. (2006). Impact of weeds on threatened biodiversity in New South Wales. Technical Series no. 11, CRC for Australian Weed Management, Adelaide. Disclaimer: This publication is provided for the purpose of disseminating information relating to scientific and technical matters. Participating organisations of the Weeds CRC do not accept liability for any loss and/or damage, including financial loss, resulting from the reliance upon any information, advice or recommendations contained in this publication. The contents of this publication should not necessarily be taken to represent the views of the participating organisations. ii CRC for Australian Weed Management • Impact of weeds on threatened biodiversity in New South Wales Table of contents biodiversity in New South Wales Impact of weeds on threatened List of tables iv List of figures vi List of acronyms vii Executive summary 1 Method 1 Threatened biodiversity examined 1 Weeds relative to other threats 1 Weeds 1 Garden escapes 2 Spatial analysis 2 Concluding comment 2 1. Introduction: biodiversity decline and weeds 3 1.1 Causes of biodiversity decline 3 1.2 Alien species introductions 3 1.3 Alien plants: an Australian perspective 3 1.4 Assessing the impacts of alien plants on biodiversity 4 2. Development of a data set on the threats to biodiversity within New South Wales 5 2.1 The data set 5 2.2 Assessment of the threat information 7 2.3 Analysis of the data set 10 3. An overview of threatened biodiversity in New South Wales 13 3.1 Nationally threatened species that occur within New South Wales 13 3.2 Biodiversity listed under New South Wales threatened species legislation 13 3.3 Distribution of threatened and non-threatened species throughout New South Wales 16 4. An overview of the major threats to biodiversity in New South Wales 19 4.1 Analysis of the major threat categories 19 4.2 Examination of the data set using the threats listed as Key Threatening Processes in New South Wales 21 4.3 Threatening processes not currently listed as Key Threatening Processes 22 5. The impacts of weeds on threatened biodiversity 25 5.1 The impact of weeds relative to the threat from alien animals 25 5.2 The relative threat posed by weeds compared to other threats 26 5.3 The threat posed by weeds 27 5.4 The impact of weeds on threatened plant and animal species 28 5.5 Actions identified by which weeds threaten biodiversity 30 6. The impact of specific weed species on biodiversity 31 6.1 Weeds impacting on biodiversity 31 6.2 Number of weed species threatening biodiversity in New South Wales 32 6.3 The most commonly identified weed species posing a threat to biodiversity 33 6.4 Impact of the Weeds of National Significance on threatened biodiversity in New South Wales 37 6.5 Impact of weeds on biodiversity listed under the Environment Protection and Biodiversity Conservation Act 1999 that occur in New South Wales 38 6.6 Assessing the origins of introduction of the weeds threatening biodiversity in New South Wales 39 6.7 The impact of garden escapes on threatened biodiversity 40 6.8 The impact of ‘weedy’ native species 42 CRC for Australian Weed Management • Impact of weeds on threatened biodiversity in New South Wales iii 7. A spatial analysis of weed threats 45 7.1 Regional distribution of weeds 45 7.2 Spatial comparisons between threatened species and weeds 49 8. Discussion and implications 53 8.1 The relative threat of weeds compared with other threatening processes 53 8.2 Assessing the impact of weeds on biodiversity 53 8.3 Weeds of National Significance and their impacts on biodiversity 55 8.4 Increasing our knowledge 55 8.5 Limiting future impacts 56 8.6 Implications for managing weed threats under the Threatened Species Conservation Act 1995 57 8.7 Assessing the impact to biodiversity more generally 58 8.8 Conclusion 58 References 59 Appendix 1 67 Appendix 2 69 Appendix 3 73 Impact of weeds on threatened biodiversity in New South Wales Impact of weeds on threatened Appendix 4 89 List of tables Table 2.1 The number and sources of threat information used, and the number of threat descriptions identified 6 Table 2.2 The seven main threat categories used in the threat hierarchy developed here, compared with those used by Wilcove et al (1998) and Lawler et al (2002) 7 Table 2.3 A summary of the threat hierarchy for alien species 8 Table 2.4 The number of threats within each threat category of the hierarchy 9 Table 3.1 The status of the biodiversity listed under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) as at January 1, 2005 14 Table 3.2 Status of the biodiversity listed under the NSW Threatened Species Conservation Act 1995 and the NSW Fisheries Management Act 1994, as at January 1, 2005 14 Table 3.3 Status of plant and animal species in New South Wales 15 Table 3.4 The proportion of species listed as threatened in each of the three geographic zones in New 16 South Wales Table 3.5 The proportion of species listed as threatened in each of the 13 Natural Resource Management regions in New South Wales 17 Table 4.1 Threatened biodiversity in New South Wales encompassed by each of the seven major threat categories in the threat hierarchy 20 iv CRC for Australian Weed Management • Impact of weeds on threatened biodiversity in New South Wales Table 4.2 Threat posed by the processes within each of the major threat categories in the threat biodiversity in New South Wales Impact of weeds on threatened hierarchy to threatened plant and animal species in New South Wales 21 Table 5.1 The relative threat of weeds to biodiversity listed under the NSW Threatened Species Conservation Act 1995 and NSW Fisheries Management Act 1994, compared with other Key Threatening Process categories 26 Table 5.2 The biodiversity threatened by weeds listed as Key Threatening Processes under the NSW Threatened Species Conservation Act 1995, as at January 1, 2005 27 Table 5.3 The threatened biodiversity threatened by weeds in New South Wales 27 Table 5.4 Endangered and Vulnerable species threatened by weeds in New South Wales 28 Table 5.5 The threat posed by weeds to threatened species in New South Wales 29 Table 5.6 The actions by which weeds were identified to pose a threat to threatened biodiversity in New South Wales 30 Table 6.1 Threatened biodiversity for which a specific weed threat was identified 31 Table 6.2 The major weed groups threatening biodiversity in New South Wales 33 Table 6.3 The 20 most commonly identified