The Status of Biological Invasions and their Management in South Africa in 2017

2017 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA SANBI National Status Report Cover.indd 1-3 2018/03/28 3:55 PM 2017 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA SANBI National Status Report Cover.indd 1-3 2018/03/28 3:55 PM 2017 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA SANBI National Status Report Cover.indd 1-3 2018/03/28 3:55 PM THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 2017 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA PRETORIA The sTaTus of biological invasions and Their managemenT in souTh africa in 2017 Lead editors: brian W. van Wilgen1 & John r. Wilson1,2 Chapter lead authors: Katelyn T. faulkner2,3, Zanele mnikathi2, Tumelo morapi2, Tendamudzimu munyai2, sebataolo rahlao2, brian W. van Wilgen1, John r. Wilson1,2 & Tsungai Zengeya2,3 With contributions from ruqaya adams2, lee-anne botha2, oupa chauke4, Jennifer fill1, Therese forsyth5, llewellyn foxcroft1,6, michelle greve8, charles griffiths7, dai herbert9, Pat holmes1,10, Philip ivey2, stiaan Kotzé4, david le maitre11, rob little12, Karabo malakalaka4, John measey1, siyasanga miza2, bernard ndou4, Khathutshelo nelukalo4, david richardson1, Tamara robinson1, ian rushworth13, ross shackleton1, heather Terrapon2, andrew Turner5, ruan veldtman2,14, giovanni vimercati1 & costas Zachariades15 1dsT-nrf centre of excellence for invasion biology, department of botany and Zoology, stellenbosch university 2south african national biodiversity institute (sanbi) 3dsT-nrf centre of excellence for invasion biology, department of Zoology and entomology, university of Pretoria 4department of environmental affairs 5capenature 6south african national Parks 7dsT-nrf centre of excellence for invasion biology, department of Zoology, university of cape Town 8department of Plant and soil sciences, university of Pretoria 9KwaZulu-natal museum 10city of cape Town 11council for scientific and industrial research 12dsT-nrf centre of excellence for birds as Keys to biodiversity conservation, university of cape Town 13ezemvelo KwaZulu-natal Wildlife 14department of conservation ecology and entomology, stellenbosch university 15Plant Protection research institute, agricultural research council Cover photographs: Top left – Argemone mexicana, yellow-flowered mexican poppy (photograph s. Turner) Top middle – Mus musculus, house mouse (photograph c. griffiths) Top right – Sagina procumbens, bird-eye pearlwort (photograph m. greve) bottom left – Vespula germanica, german wasp (photograph s. van noordt) bottom middle – Pinus species, pine trees (photograph b. van Wilgen) bottom right – Sturnus vulgaris, common starling (photograph c. griffiths) Technical editing: sanbi graphics & editing design & layout: ink design cover design: ink design Citing this publication for citations in the scientific literature: van Wilgen, b.W. & Wilson, J.r. (eds.) 2018. The status of biological invasions and their management in South Africa in 2017. south african national biodiversity institute, Kirstenbosch and dsT-nrf centre of excellence for invasion biology, stellenbosch. For citations in policy documents: SANBI and C•I•B, 2018. The status of biological invasions and their management in South Africa in 2017. south african national biodiversity institute, Kirstenbosch and dsT-nrf centre of excellence for invasion biology, stellenbosch. ISBN: 978-1-928224-18-1 Printed by: novus Print solutions, 26 freedom Way, milnerton, cape Town 7441 south africa. e-mail: info[email protected]. www.novus.holdings copyright © 2018 south african national biodiversity institute (sanbi). all rights reserved. reproduction of this publication for educational or other non-commercial purposes is authorised without prior written permission from the copyright holder provided the source is fully acknowledged. reproduction of this publication for resale or other commercial purposes is prohibited without prior written permission of the copyright holder. iii Furcraea foetida (Mauritian hemp) – SANBI INDEPENDENCE OF THE STATUS REPORT This status report constitutes an independent assessment of the status of biological invasions and their management in South Africa. It is the fi rst such country-level assessment specifi cally on biological invasions anywhere in the world. The report is intended to inform the development and ongoing adaptation of appropriate policies and control measures, both to reduce the negative impacts of invasive species on ecosystems, the economy, and people, and to retain any benefi ts of invasive species where possible and desirable. The compilation of the report was overseen by a team of editors and contributing authors employed by the South African National Biodiversity Institute (SANBI) and the DST-NRF Centre of Excellence for Invasion Biology at (C•I•B). Inputs (including data, peer-reviewed papers, and unpublished reports) were also obtained from researchers and managers from diverse institutions across South Africa. Funding for the compilation of the report was obtained through the national Department of Environmental Aff airs (DEA) as part of SANBI’s Medium Term Expenditure Framework. In order to address any potential confl icts of interest, and to ensure independence of the report, the following steps were taken: • Drafts of the status report were widely circulated to contributing authors and other stakeholders, who were invited to submit comments, concerns or additional information, with two dedicated rounds of review in 2017; • Comments and concerns raised were captured in a database, along with the drafting team’s responses to these comments and concerns. This database is available on request; • A Review and Advisory Committee was appointed, chaired by an expert on assessments, from the University of the Witwatersrand, South Africa. This committee approved the review process and took responsibility for ensuring editorial independence; and • An independent Review Editor will be appointed to assess the review process on completion of the fi rst status report, with a view to strengthening the process if necessary for future reports. iv EDITORIAL CONVENTIONS Species Both scientifi c and common names are provided when referring to species. Authorities for scientifi c names are provided in Appendix 3, and are not used in the main text or in tables. Each species is assigned only one common name. The common name used is in English, recognising that more than one English common name may exist, and that common names in other South African offi cial languages also exist. Exceptions are made when a nonEnglish common name is predominantly or exclusively used to describe a species (e.g. in the case of Acacia cyclops, the common name “rooikrans” is used in preference to the English “red eye”). Acronyms All acronyms are defi ned at fi rst use in every chapter, and are also defi ned in table headings and in the legends of fi gures. A full list of acronyms and their defi nitions is provided at the beginning of the report. Terminology To assist the reader who may not be familiar with commonly-used terms in invasion biology, a glossary of terms is provided at the beginning of the report. Currency South African rands are denoted as ZAR, and not R. References All references for the text and for appendices are provided in a single list at the end of the report. In the bibliography, references with more than ten authors only have the fi rst four authors listed, followed by “et al.” Indicators All indicators are numbered wherever they are mentioned in the text or in tables. The numbering of indicators follows the numbers set out in Chapter 2. TABLE OF CONTENTS INDEPENDENCE OF THE STATUS REPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III EDITORIAL CONVENTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .X LIST OF ACRONYMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .XII GLOSSARY OF TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XIII EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . XVI 1. INTRODUCTION Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1. The importance of biological invasions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Purpose of the status report on biological invasions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3. Legislative background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.4. Aspects of biological invasions that are not covered . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5. Structure of the status report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.6. Process followed to produce this status report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2. INDICATORS Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.2. The rationale for the approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.3. Confi dence levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.4. Indicators used in this report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.4.1. Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.4.2. Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.4.3. Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4.4. Interventions (eff ectiveness of control measures and regulations) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.5. High-level Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.6. Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3. PATHWAYS OF INTRODUCTION Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 3.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.2. Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 3.3. Status of the pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.3.1. Status of the pathways of introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 3.3.2. Status of the pathways of dispersal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 3.3.3. Future changes to the pathways of introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 3.4. Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 3.5. Synthesis and indicator values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 4. THE STATUS OF ALIEN SPECIES Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 4.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 4.2. The number and status of alien species in South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 4.2.1. Number of alien species in South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 4.2.2. Status of alien species in South Africa. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 4.3. The Extent of alien species in South Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.3.1. Number of broad-scale regions occupied per species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 4.3.2. Number of quarter degree grid cells occupied per species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 4.4. Abundance of alien species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.5. The impact of alien species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 4.6. Synthesis and indicator values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5. THE STATUS OF INVADED AREAS Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 5.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 5.2. Alien species richness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 5.2.1. Invasive species richness per large-scale national sub-division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 5.2.2. Invasive species richness per fi ner-scale national sub-division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 5.2.3. Alien species richness at diff erent stages of the Unifi ed Framework for Biological Invasions . . . . . . . . . . . . . . . . . . 77 5.3. Relative alien species richness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.4. Relative invasive abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.5. Impact of invasions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 5.5.1. Impacts on surface water runoff and groundwater by primary catchment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 5.5.2. Impacts on rangeland productivity by biome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 5.5.3. Impacts on biodiversity intactness by biome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 5.5.4. Impacts on fi re regimes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 5.5.5. Impacts on marine habitats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 5.6. Synthesis and indicator values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 6. THE EFFECTIVENESS OF CONTROL MEASURES Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 6.2. Pathway-related control measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 6.3. Species-specifi c control measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 6.3.1. The status of attempts at eradication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 6.3.2. Biological control of invasive plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .100 6.3.3. Invasive species management programmes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103 6.3.4. Management of invasive plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 6.3.5. Management of invasive freshwater fi sh . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 6.3.6. Management of invasive mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .106 6.3.7. Management of invasive herpetofauna . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107 6.3.8. Management of invasive invertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 6.4. Area-specifi c control measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108 6.4.1. Assessment of eff ectiveness at a national scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108 6.4.2. Assessments of control eff ectiveness at fi ner scales where information is available . . . . . . . . . . . . . . . . . . . . . . .109 6.4.3. Returns on investment from control measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114 6.4.4. Negative impacts of control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116 6.5. Synthesis and indicator values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .116 6.5.1 Overall eff ectiveness of control measures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 6.5.2. Allocation of values to indicators of pathway management eff ectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 6.5.3. Allocation of values to indicators of species management eff ectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 6.5.4. Allocation of values to indicators of area management eff ectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 6.5.5. Estimation of high-level indicators for overall management eff ectiveness . . . . . . . . . . . . . . . . . . . . . . . . . . 126 7. EFFECTIVENESS OF REGULATIONS Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130 7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .132 7.2. The state of the current regulatory framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134 7.2.1. What is required to improve the eff ectiveness of the regulations? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134 7.3. Eff ectiveness of regulations relevant to managing alien species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137 7.3.1. Permits issued for the import of new species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 7.3.2. Permits issued for listed invasive species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138 7.3.3. Invasive species management programmes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142 7.3.4. Emergency interventions and enforcement actions involving listed invasive species . . . . . . . . . . . . . . . . . . . . . . 142 7.3.5. Risk assessments of listed species, or candidates for listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 7.4. Regulations relevant to managing specifi c areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147 7.4.1. Notifi cations from landowners regarding alien species on their land . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147 7.4.2. Notifi cations and directives issued to landowners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147 7.4.3. Level of compliance with property transfer notifi cations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153 7.4.4. Invasive Species Monitoring, Control and Eradication Plans (i.e. area management plans) . . . . . . . . . . . . . . . . . .154 7.4.5. Status reports for protected areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 7.5. Research proposal and reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156 7.6. Prosecutions under the regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 7.7. Synthesis and indicator values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157 8. KNOWLEDGE AND INFORMATION GAPS IN UNDERSTANDING THE STATUS OF BIOLOGICAL INVASIONS Chapter summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159 8.1. Approach used in this chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .160 xv • Listed alien species: all alien species that are regulated under the National Environmental Management: Biodiversity Act, 2004 (Act no. 10 of 2004), Alien and Invasive Species (A&IS) Regulations, 2016. • Native species: see Indigenous species. • Naturalised (syn. established): Alien species that sustain self-replacing populations for several life cycles or over a given period of time without direct intervention by people, or despite human intervention. • Net present value: the present-day value of money when compared to its past value after factoring in infl ation. • Pathways: a broadly defi ned term that refers to the combination of processes and opportunities that result in the movement of alien species from one place to another. • Permit: an offi cial document issued in terms of Chapter 7 of National Environmental Management: Biodiversity Act, 2004 (Act no. 10 of 2004). • Pest (cf. environmental pest and weed): an organism that causes negative impacts. The aff ected sector might be specifi ed, so an agricultural pest will impact negatively on agricultural production. Pests can be alien or indigenous, and are usually taken to refer to animals, with pest plants more specifi cally referred to as weeds and pest fungi or microbes referred to as diseases. • Pre-introduction: a stage in the invasion process where a species is not currently present in a region of interest. • Prohibited species: species that are not native to South Africa listed as prohibited under the National Environmental Management: Biodiversity Act, 2004 (Act no. 10 of 2004) Alien and Invasive Species (A&IS) Regulations, 2016. These species are assumed to be absent from the country and new introductions are prohibited. • Propagule pressure: a concept that encompasses variation in the quantity, quality, composition and rate of supply of seeds, individuals, or other reproductively viable material of an alien species resulting from the transport conditions and pathways between source and recipient regions. • Port of entry: an offi cial point of entry or departure from South Africa through which goods and people may enter or leave a country, for example a border post, airport or harbour. • Regulation: a law, rule or other order prescribed by authority, especially to regulate conduct. • Risk analysis: the assessment of the nature, likelihood and consequences of a given alien taxon causing negative impacts (i.e. risk assessment), and the identifi cation of measures that can be implemented to reduce or manage such risk, taking into account socio-economic considerations. • Risk assessment: part of risk analysis, assessing the nature, likelihood and consequences of a given alien taxon causing negative impacts. • Spread: see Expansion. • Status: the state, condition or stage of aff airs at a particular time. • Taxon (pl. taxa): a group of organisms that all share particular properties (usually evolutionary history). The grouping can be below, at, or above the species level. • Unifi ed Framework: a framework the defi nes biological invasions in terms of the introductionnaturalisation-invasion continuum and provides a method for categorising alien species in terms of their introduction status (see Appendix 3 for details). • Vectors: a broadly defi ned phenomenon involving dispersal mechanisms that can be both non-human and human mediated. It is often used to refer to the actual mechanism by which alien species are able to arrive at new areas. • Weed (cf. pest, environmental weed): a plant that causes negative impacts. Weeds can either be alien or native. xvi THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 EXECUTIVE SUMMARY1 Biological invasions are a large and growing environmental problem, globally and in South Africa. Many thousands of species have been translocated from their indigenous ranges to novel environments, where some become invasive and spread across natural ecosystems, threatening indigenous biodiversity and reducing the ability of ecosystems to deliver vital services. These biological invasions often have direct negative impacts on the wellbeing of many people, and in particular threaten rural livelihoods. This report constitutes the fi rst comprehensive attempt to assess the status of biological invasions across all aspects of the problem at a national level. The report is based on information from a range of sources, including inputs from experts and practitioners, atlas data, published scientifi c papers and theses, and management records from government agencies. Draft versions of the report were sent out to a wide and representative range of interested parties in two rounds of review, which resulted in the inclusion of additional information. This report does not cover the social benefi ts associated with alien species control programmes that are implemented with the additional goals of employment creation and poverty relief, as this is not required in terms of the regulations, as well as because there have been no attempts to date to quantify these benefi ts. However, these benefi ts should ideally be considered when returns on investment from control projects are calculated. The report is structured around four aspects: pathways of introduction and dispersal; the number, distribution and impact of individual species; species richness and abundance of alien species in defi ned areas, and their impacts on those areas; and the eff ectiveness of interventions, i.e. Have South African regulations and control eff orts been eff ective in reducing the problem? A total of 21 indicators were developed to assess the status of these aspects. In addition, four high-level indicators (one for each aspect) were developed for use in the national suite of environmental indicators on which the Department of Environmental Aff airs reports on a regular basis. Most alien species found in South Africa today were intentionally introduced many years ago, either deliberately with the goal of establishing populations in nature, or for horticulture, agriculture, forestry or the pet trade (from where some escaped to become invasive). The remainder were introduced accidentally as commodity contaminants or as stowaways on transport vectors. While the rate of intentional introduction of high-risk species is expected to decline due to improved regulation, it is also expected that the rate of unintentional introductions will increase due to increases in trade and tourism. The rate at which species are arriving in the country appears to be gradually increasing.. Once an alien species is introduced to South Africa, further spread within the country 1 This executive summary provides a brief, high-level overview of the contents of this report. More detailed summaries appear at the start of each chapter. Chapter 9 also provides a set of key policy-relevant messages. xvii PREFACE is highly likely and very diffi cult to stop. There is a thriving trade in alien species for a variety of purposes within South Africa’s borders. Alien species can also be accidentally transported along the country’s extensive transport networks, and invasive species can spread naturally. A total of 556 invasive taxa have been listed under the National Environmental Management: Biodiversity Act’s Alien and Invasive Species Regulations. The actual number of invasive species is higher, with 775 having been identifi ed to date. Most of these invasive species are terrestrial and freshwater plants (574 species) or terrestrial invertebrates (107 species). A total of 107 species were considered by experts to be having either major or severe impacts on biodiversity and/or human wellbeing; the vast majority of these (75%) were terrestrial or freshwater plants. Alien species richness was highest in the Savanna, Grassland, Indian Ocean Coastal Belt and Fynbos biomes, with relatively low species richness in the more arid Karoo and Desert biomes. Alien trees and shrubs can dominate areas such as fynbos catchments and coastal areas; mesquite trees (Prosopis spp.) dominate arid areas; many riparian zones are invaded by trees; many rangelands are invaded by cacti and herbaceous annual and perennial plants; and few indigenous fi sh species survive in streams invaded by alien fi sh. There are very few studies that cover the combined impacts of invasive species on particular areas. Available studies estimate the combined impacts of invasive plants on surface water runoff at between 1450 to 2450 million m3 per year. If no remedial action is taken, reductions in water resources could rise to between 2600 and 3150 million m3 per year, severely impacting drought-stricken cities like Cape Town. Reductions in the productivity of rangelands, and in biodiversity intactness, are low at present (between 1 and 3%), but these impacts are expected to grow rapidly as invasive plants enter a stage of exponential growth. Biological invasions account for 25% of the reduction in South African biodiversity seen to date. In terms of control measure inputs, South Africa’s Alien and Invasive Species Regulations are substantial, as they cover most aspects of the problem. Large sums of money have been spent (currently ZAR1.5 billion per year), especially on the control of terrestrial and freshwater plant species. This is almost certainly an underestimate as it only includes funding from the Department of Environmental Aff airs, and not from other government or semigovernment entities, or the private sector. Planning coverage is low, and there is little evidence of adequate levels of goal-setting or monitoring. xviii Control measure outputs are assessed in terms of the proportion of pathways, species or areas that have been subjected to control. The Convention on Biological Diversity recognises 44 pathways of introduction, and 34 of these pathways (77.3%) are managed to some extent. Although 556 taxa are listed in the Alien and Invasive Species regulations, not all of these are subjected to active management. For example, ~126 out of 379 alien terrestrial and freshwater plant taxa have been targeted for some control, and of these, eight species make up 80% of the area subjected to treatment. In terms of areas, less than 1% of invaded land has been reported to have been the subject of control measures. Data on the outcomes of control measures are sorely lacking. The impact of pathway regulation on rates of introduction of invasive species cannot yet be determined, given that they have only been in place for a short time. Control measures have been shown to be eff ective in some localized areas but not so in others. While the situation would arguably have been worse had there been no control, current control eff orts have not been eff ective in preventing the ongoing spread of invasive species when viewed at a national scale. The level of confi dence in almost all these estimates is low. This can be improved in future status reports as more data are collated and curated, but in many cases new processes are required to monitor and report on biological invasions if policy and management decisions are to be evidence-based. In particular three key areas of focus are identifi ed: (1) the need for more research to determine and assess the impacts of alien species; (2) better monitoring of the eff ectiveness of current control measures; and (3) the development of methods to look at the impact of biological invasions and their management on society as a whole. The report concludes by providing a list of policy-relevant messages that have been distilled from the assessment, and these should be considered when formulating environmental policies for the country as a whole. Besides expanding on the points described above, it is noted that it should be imperative to improve management effi ciency, given the substantial economic and social consequences that would be associated with a failure to adequately address the problem of biological invasions. This will require diffi cult choices and trade-off s to be made, including the need to practice conservation triage by focussing eff ort on priority pathways, species, and areas. Acridotheres tristis (common myna) – Richard Taylor 1 INTRODUCTION Lead authors: Brian van Wilgen, John Wilson Contributing authors: Sebataolo Rahlao, Tsungai Zengeya Chapter summary Biological invasions can have profound negative impacts on biodiversity, reduce the ability of ecosystems to deliver the services needed to maintain and improve the livelihoods of the people of South Africa, and impact directly upon people’s wellbeing. This report presents the fi rst comprehensive national-scale assessment of the status of biological invasions in South Africa, and the fi rst such country-level assessment specifi cally on biological invasions anywhere in the world. The report is intended to inform the development and ongoing adaptation of appropriate interventions to reduce the negative impacts of biological invasions on biodiversity and ecosystems, the economy, and people, while preserving any benefi ts. Status is addressed in terms of fi ve aspects: pathways of introduction and spread; the establishment, distribution, and impact of species; the level to which areas are invaded and the resulting overall impacts; the eff ectiveness of control measures; and the eff ectiveness of regulations. This report also fulfi ls the legal requirement for the South African National Biodiversity Institute to submit a report on the status of biological invasions, and the eff ectiveness of control measures and regulations, to the Minister of Environmental Aff airs. This fi rst report also provides a framework for future reports, with reports due every three years. This chapter briefl y describes the process followed to produce the report, which included the appointment of a Reference and Advisory Committee to provide guidance and advice, the gathering of information from a wide range of sources, and review by stakeholders and contributors. EFFECTIVENESS OF RESPONSES The current eff ectiveness of management interventions varies. In some cases, good progress has been made, but in others the interventions have been less eff ective. Undoubtedly, we would be worse off if no action had been taken, but eff ectiveness can be increased substantially by better planning and monitoring and the more widespread use of accepted best-practice control measures. Lythrum hyssopifolia (hyssop loosestrife) – Christian Fischer 2 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 1.1. THE IMPORTANCE OF BIOLOGICAL INVASIONS Biological invasion is the phenomenon of the transportation of organisms through intentional or accidental human activity to areas outside of their natural range, and the fate of such organisms in their new ranges, including their ability to survive, establish, reproduce, disperse, spread, proliferate, and infl uence invaded ecosystems (Richardson et al., 2011a). Biological invasions are a growing environmental problem worldwide, and South Africa in particular is home to a large and growing number of invasive species. Thousands of species have been introduced to South Africa over the years. Many of these alien species are benefi cial. Almost all agriculture and forestry production is based on alien species, and alien species are widely used in horticulture, aquaculture, and mariculture, or are kept as pets. Only a small proportion of alien species become invasive though this varies markedly between taxa (~0.1–10%). This subset of alien species can reduce the ability of ecosystems to deliver services, negatively aff ecting the economy of invaded areas, and ultimately impacting upon all South Africans. Invasive trees and shrubs reduce water runoff and groundwater recharge, reducing the water supplies to already-stressed farms, towns and cities; plants that invade rangelands reduce the capacity of the land to support livestock and threaten the livelihoods of people that depend on livestock production; and invasive plants and animals impact negatively on biodiversity and the services that South Africa’s diverse natural ecosystems provide (from ecotourism to harvesting food, cut fl owers, and medicinal products). In 1996, South Africa adopted a new Constitution (Constitution of the Republic of South Africa Act, Act 108 of 1996). The Bill of Rights (Chapter 2) is central to this Constitution as it enshrines the rights of all people in the country. Section 24 of the Bill of Rights guarantees the right to an environment that is not harmful to people’s health or wellbeing, and provides for environmental protection for the benefi t of future generations through reasonable legislative and other measures that prevent “ecological degradation, promote conservation, and secure ecologically sustainable development”. This imparts a responsibility both to control invasive species so as to reduce their negative impacts, and to try to preserve any benefi ts that such invasive species may provide. Crucially this is not only a matter of balancing ecological and economic imperatives, as in some situations invasive species are economically useful to some people but economically damaging to other people Van Wilgen & Richardson, 2014; Woodford et al., 2016). South Africa has been actively managing biological invasions for well over a century (e.g. Moran, Hoff mann & Zimmermann, 2013). While historically the focus was on limiting direct impacts to agricultural production, the ultimate goal of these measures is to prevent the erosion of ecosystem services and to protect people from the ongoing expansion of negative impacts. This is in line with the constitutional obligation. 1.2. PURPOSE OF THE STATUS REPORT ON BIOLOGICAL INVASIONS This status report is intended to inform the development and ongoing adaptation of appropriate policies and control measures, both to reduce the negative impacts of invasive species on ecosystems, the economy, and people, and to retain any benefi ts of invasive species where possible and desirable. Such control measures and policies ideally need to be based on an understanding of the dynamics of biological invasions, the magnitude and distribution of the impacts of biological invasions, an assessment of the implications of those impacts, and 3 CHAPTER 1 I INTRODUCTION on the prospects for containing or reducing them. Once management goals are set and implemented, their outcomes should be monitored and evaluated regularly, with observations feeding back to adjust priorities for basic inventory and ecological research. However, this process is rarely as straightforward as this (Figure 1.1). This status report synthesizes current understanding of the problem arising from inventories and ecological research, as well as on the outputs of exercises to monitor and evaluate the outcomes of control measures, in a form that is of value to policy makers and managers. The current requirement is to repeat this cycle every three years (see section 1.3 below). Basic inventory and ecological research Assess implications and formulate policy Set goals and implement management measures Monitoring and evaluation A Basic inventory and ecological research Assess implications and formulate policy Set goals and implement management measures Monitoring and evaluation B STATUS REPORT FIGURE 1.1 The National Status Report is a formal mechanism to increase the connectivity between research, policy and implementation. The top panel (A) shows an idealised process whereby research is conducted that is interpreted in terms of implications for management expressed in appropriate policy, which in turn is implemented. Implementation is monitored and evaluated and adjusted accordingly, i.e. management is adaptive. How and what is monitored and evaluated is informed by basic inventory and ecological research and vice versa. The bottom panel (B) shows the real situation. There are sometimes direct links between basic research and implementation, and many more feedbacks, but often the links are incomplete or broken. Diff erent people and organisations are involved in research, policy formulation, management, and evaluations, and their specifi c goals and interests are often not closely aligned, nor do they always have the time to interact. There is a variety of mechanisms to increase communication between diff erent role players. A national status report is one formal way of collating information from basic inventories and ecological research and from monitoring and evaluation, and providing it in a form that can assist with the processes of assessing implications and formulating appropriate policy, and setting goals and implementing management measures. FACT The National Status Report on Biological Invasions in South Africa is the fi rst such report anywhere in the world. Its purpose is to set a benchmark against which trends in this problem can be tracked over time. 4 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 1.3. L EGISLATIVE BACKGROUND Historically, South Africa has responded to the threat posed by invasive species by ad hoc, often piecemeal, legislation. Recently, there has been a more comprehensive sector-specifi c approach. In particular, regulations under the Conservation of Agricultural Resources Act (CARA) (Act 43 of 1983), were promulgated to govern the management of certain (listed) invasive plant species (“weeds”); while the Agricultural Pests Act, 1983 (Act 36 of 1983) provides for measures to combat agricultural pests and prevent their introduction. Despite the initial intent of the CARA (which was to control agricultural weeds), the species listed included plants whose impacts were primarily felt in untransformed natural ecosystems, i.e. environmental weeds. In 1998, the National Environment Management Act (NEMA) (Act 107 of 1998) was enacted to provide a framework for environmental management. In 2004, the National Environmental Management: Biodiversity Act (NEM:BA, Act 10 of 2004) was passed. NEM:BA is one of the laws built around the NEMA framework, and is intended to promote the protection and conservation of South Africa’s rich biodiversity. In 2014, a set of regulations was promulgated in terms of this Act, by which the management of biological invasions is to be governed. These regulations address the import of new alien species, place existing alien species into a number of categories, and specify how these species are to be controlled or managed. One of the specifi c requirements contained in these regulations is for the South African National Biodiversity Institute (SANBI) to produce regular status reports (Box 1.1). Section 2 of NEM:BA states that South Africa should “give eff ect to ratifi ed international agreements relating to biodiversity which are binding on the Republic”. The most important of these agreements is the Convention on Biological Diversity (CBD), which South Africa ratifi ed in November 1995. Article 8(h) of this convention requires each Contracting Party, as far as possible and as appropriate, to “prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species”. Article 19 also requires each contracting party to take legislative, administrative or policy measures to provide for eff ective participation in the convention. Other relevant conventions include the International Plant Protection Convention (IPPC), which requires that signatory countries meet requirements designed to reduce the risks of pests of plants from either leaving or entering the country (while pests originally referred to animals and fungi, the IPPC defi nition has recently been expanded to include plants as pests themselves). From a marine perspective, the UN Convention on the Law of the Sea obliges parties to prevent, reduce and control the intentional or accidental introduction of species to the marine environment where they may have signifi cant harmful eff ects. The International Convention for the Control and Management of Ship’s Ballast Water and Sediments imposes obligations to prevent, minimise, and ultimately eliminate the transfer of harmful aquatic organisms and pathogens through the control and management of ship’s ballast water and sediments. EFFECTIVENESS OF RESPONSES South Africa has comprehensive national regulations to deal with biological invasions. Many provisions are innovative, allowing for benefi ts to be derived from some invasive species while simultaneously requiring their control where it is required. The regulations have only been in force for three years, so it is too early to be able to assess the degree to which they have aff ected the status of biological invasions in the country. 5 CHAPTER 1 I INTRODUCTION BOX 1.1 REGULATORY REQUIREMENT FOR A NATIONAL STATUS REPORT In terms of section 11 of the Alien and Invasive Species Regulations promulgated under the National Environmental Biodiversity Act (NEM:BA) (Act 10 of 2004), the South African National Biodiversity Institute (SANBI) is required to draw up a status report on biological invasions. The wording of the relevant section of the regulations is as follows: 1. The Institute [i.e. SANBI] or a body designated by the Institute must, for the purpose of reporting as contemplated in section 11(1) (a) (iii) of the Act, submit a report on the status of listed invasive species to the Minister within three years of the date on which these regulations come into eff ect, and at least every three years thereafter [the regulations came into eff ect on 1 October 2014]. 2. A report contemplated in sub-regulation (1) must contain a summary and assessment of: a. the status of listed invasive species and other species that have been subjected to a risk assessment; and b. the eff ectiveness of these regulations and control measures based inter alia on information from: i. notifi cations received from owners of land regarding listed invasive species occurring on their land; ii. permits issued for listed invasive species; iii. Invasive Species Monitoring, Control and Eradication Plans received from organs of state and management authorities of protected areas; and iv. emergency interventions and enforcement actions involving listed invasive species issued by the Minister. 5. In preparing a report contemplated in sub-regulation (1), the Institute must carry out the research and monitoring necessary to identify the matters contemplated in sub-regulation (2). Note: the “Invasive Species Monitoring, Control and Eradication Plans” referred to in the regulations are intended to be drawn up for specifi c areas. For the purposes of this report these are referred to as area management plans. This is distinct from species management programmes which focus on controlling particular species often across the whole of South Africa. 1.4. ASPECTS OF BIOLOGICAL INVASIONS THAT ARE NOT COVERED Box 1.1 outlines what has to be covered in the report, but it is worth explicitly noting what is not considered. First, as the status report’s primary function is to report on environmental issues, this initial report has a limited focus on the socio-economic problems caused by biological invasions. The most damaging invasive species are human diseases. These are not included in this report. Similarly, pests and weeds that aff ect agricultural crops are a major threat to sustainable development, but are not within this report’s remit unless such taxa also impact upon, or threaten, natural ecosystems. Secondly, there is a suite of indigenous species that can have undesirable impacts that are similar to the impacts caused by alien species, but which are precipitated by changes in land use or other aspects of global change. Examples include bush encroachment by indigenous plants, and the spread of many indigenous bird species into urban areas. These can present particular problems, but their management needs to be in the context of them as indigenous to the region and as pests within their indigenous ranges. Finally, the social benefi ts associated with alien species control programmes that are implemented with the additional goals of employment creation and poverty relief are not covered in this report, as this is not required in terms of the regulations, as well as because there have been no attempts to date to quantify these benefi ts. However, these benefi ts should ideally be considered when returns on investment from control projects are calculated (Box 1.2). 6 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 See Chapter 8 for a more detailed discussion of gaps, challenges, and potential directions for future reports. BOX 1.2 SOCIAL BENEFITS ASSOCIATED WITH INVASIVE ALIEN PLANT CLEARING PROGRAMS This report assesses the status of biological invasions and the eff ectiveness of control and regulatory measures in South Africa, as required by section 11of the Alien and Invasive Species Regulations (Box 1.1). Most of the alien plant control projects across the country are funded by the Working for Water (WfW) Programme (Box 6.2), which is an Expanded Public Works programme of government and has the dual goals of providing employment and development opportunities to disadvantaged individuals in rural areas, as well as managing invasive alien species. The social goals, besides providing a direct income to tens of thousands of benefi ciaries, include attempts to develop entrepreneurial and other skills. WfW has adopted employment practices which ensure that previously disadvantaged individuals, women, the youth, and people living with disabilities are given priority. The magnitude and impact of these social benefi ts has not been formally quantifi ed, but it should be noted that these benefi ts need to be considered when determining the full extent of returns on investment arising from alien species control projects (see section 6.4.3 of the report). This has not been addressed in this status report as the issue falls outside of the mandate of this report, and also because there are no reliable estimates of the magnitude of the social benefi ts. Benefi ciaries employed by the Working for Water Programme in the Eastern Cape Province. Benefi ts reach over 30000 people across South Africa every year (Photograph: B. van Wilgen). 2 INDICATORS Lead authors: John Wilson, Brian van Wilgen Contributing authors: Katelyn Faulkner, David Richardson, Sebataolo Rahlao, Tsungai Zengeya Chapter summary This chapter outlines the development of a set of 21 indicators for assessing three main aspects of invasions (pathways, species, and areas), as well interventions (in terms of both the eff ectiveness of control measures, and the eff ectiveness of the regulations). For each indicator, a fact-sheet was developed, outlining how the indicators are to be measured and providing a method for ascribing a level of confi dence when assigning values to indicators. Indicators for pathways describe the opportunities available for introduction to and dispersal within South Africa, as well as the degree to which alien species are being introduced along these pathways. Indicators for species include the number and status of alien species in the country, the extent and abundance of these alien species, and the impacts caused. Indicators for invaded areas include the number of alien species in diff erent areas, the alien species richness relative to indigenous species richness, the abundance of invasive species relative to the abundance of indigenous species, and the impact of invasions on particular areas. Indicators for the interventions include an assessment of key inputs (the regulatory framework, the money spent and the planning coverage), outputs (the degree and quality of treatments applied to pathways, species and areas) and outcomes (the eff ectiveness of treatments of pathways, species and areas, as well as returns on investment). This chapter also proposes four high-level indicators: 1) the rate of introduction of new unregulated species; 2) the number of invasive species that have major impacts; 3) the extent of area that suff ers major impacts from invasions; and (4) the level of success in managing invasions. Acacia paradoxa (Kangaroo thorn) – John Wilson 14 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 2.1. INTRODUCTION A set of robust indicators is needed to provide a comprehensive picture of the state of biological invasions. While there has been some progress towards this goal at an international level (Hawkins et al., 2015, Latombe et al., 2017), much remains to be done. It was clear that South Africa’s fi rst national status report should build on these international initiatives, but it was also necessary to develop additional indicators to cover those aspects that were not yet catered for in the developing international framework. In addition, there is a specifi c need to include indicators that directly address the reporting requirements outlined in the regulations. Furthermore, there are no data available to accurately assign values to some indicators for South Africa, nor will it be feasible to collect such data in the medium-term. The process of indicator development in this area will need to continue both in terms of fundamental research, and as part of the development of a practical and informative monitoring framework for biological invasions in South Africa. As such, the indicators proposed here constitute a compromise, partly from international frameworks, partly from fi rst principles, partly simply in terms of a refl ection of which data are currently available, while ensuring that there is alignment with the requirements in the regulations. This chapter presents a set of indicators for use in establishing the status of biological invasions in South Africa based on basic inventory and ecological research and the monitoring and reporting of the eff ectiveness of regulations and control measures (Figure 2.1). This chapter also presents a methodology for ascribing a level of confi dence when assigning values to these indicators. 2.2. THE RATIONALE FOR THE APPROACH The phenomenon of biological invasions is caused by a combination of how taxa are moved around by humans (introduction dynamics), the traits of individual taxa (invasiveness), and the susceptibility of the environment to EFFECTIVENESS OF RESPONSES A set of four high-level indicators has been developed to track trends in: A the rate of introduction of new unregulated species to South Africa 7 PER YEAR B the number of invasive species that have major impacts 107 SPECIES C the extent of South Africa that suff ers major impacts from invasions 1.4% OF THE LAND AREA D the level of success in managing invasions 5.5% The values assigned to these indicators set a baseline against which trends in future can be measured, with the overall goal being to implement control and regulatory measures that will improve the situation as measured by these indicators. 15 CHAPTER 2 I INDICATORS invasions (invasibility). For example, the current distribution of invasive pines in South Africa is a result of how pines have historically been planted for forestry, which species have particular traits that predispose them to invade, and the fact that some areas of the country do not have any indigenous fi re-adapted tree species and so are susceptible to woody plant invasions (e.g. the Cape Floristic Region). The explicit consideration of biological invasions in terms of these three aspects [i.e. pathways, species (or more precisely taxa), and areas] is also crucially important for management. Focussing on pathways is important to reduce rates of introduction and spread, but does not address current invasions. Focussing on species can be highly eff ective in reducing densities of a single species, but can simply clear the way for other species to invade. Integrated and strategic approaches are needed to deal with suites of co-occurring species in any given area, but if management is to be eff ective in those areas, pathways of introduction need to be managed and in most cases best practice species-specifi c control measures will need to be implemented. The invasion process is commonly categorised in terms of an introduction-naturalisation-invasion continuum (Blackburn et al., 2011). There are four major invasion stages – pre-introduction, incursion, expansion, and dominance – that align with four management goals – prevention, eradication, containment, and impact reduction. The combination of the need to look at indicators for pathways, species and areas, as well as the need to look at pre-introduction, incursion, expansion and dominance, gives rise to the 3×4 framework. This framework was the basis of the draft National Strategy on Biological Invasions in South Africa, and is discussed in detail by Wilson, Panetta & Lindgren (2017). However, the development of indicators for all aspects of invasions at all invasion stages still requires some theoretical development. This report concentrates on indicators for the three aspects (pathways, species, and areas), and not on the four stages (pre-introduction, incursion, expansion, and dominance), although a future report may seek to develop the indicators needed to cover all components of the 3 × 4 framework. There are, of course, many other ways of conceptualising or categorising biological invasions. Taxonomic, disciplinary or functional lines could also be used, e.g. by considering freshwater fi sh invasions and riparian plant invasions as separate problems. Alternatively, a status report could be divided into specifi c biomes, environments or realms. South Africa’s National Biodiversity Assessment has, to date, taken this approach and is presented as a series of chapters based on ‘realms’ – freshwater, marine, and terrestrial. In terms of biological invasions, there is, however, no neat separation between aquatic and terrestrial environments, nor between fi sh, frogs, and ferns – the essence of the problem is the same. If propagule pressure can be reduced, will this reduce the likelihood of an invasion? What are the impacts? Is a species defi nitely alien? Management often needs to consider entire systems, e.g. simultaneously managing freshwater fi sh invasions and riparian plant invasions would lead to a more sustainable outcome than if either group was controlled on its own (Impson, Van Wilgen & Weyl 2013); and the same pathway (e.g. the pet-trade) can be responsible for introducing marine, terrestrial and freshwater organisms. So while it is important to be able to report along geographical or taxonomic lines, not least as this is frequently the level at which data are collected or management is implemented, it is important that such data can be aggregated to give higher level indicators. In this report, the indicators themselves are not split into geographical or taxonomic lines, but the report will consider groupings within each indicator as per the data sources themselves [e.g. the Southern African Plant Invaders Atlas (SAPIA) includes data on alien plants across all habitat types except marine and some coastal habitats]. 16 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 For the report to be of value it should provide information that can be used to determine how eff ective interventions have been in reducing the size of current problems. The approach taken in this report is to assess the eff ectiveness of interventions (which is composed of both the eff ectiveness of control measures and the eff ectiveness of regulations) in terms of how they infl uence aspects of pathways, species or areas. Specifi cally indicators are presented for inputs (e.g. the amount of money spent), outputs (i.e. control measures that are in place), and the outcomes (i.e. how eff ective the control measures are). In this report, indicators are not, however, developed for: 1) the underlying processes required for those interventions; or 2) the ultimate impact of the interventions. Interventions require a suite of enabling processes (specifi cally: accessibility of data and information; organisational and human capacity; research; and public awareness and engagement), but as these are not directly related to outputs that aff ect outcomes they are not considered here. Developing indicators for these enabling processes might be a priority for future reports. Secondly, if the implications of any intervention for the broader South African community are to be assessed, there must be a link made to general environmental and socio-economic indicators, i.e. the impact. In this report, this link is not made explicit nor is an attempt made to develop indicators specifi cally for this (as it is more appropriate to co-opt existing sector-specifi c indicators). It is anticipated that developing the link between what is done in this report (i.e. assessing impact in terms of specifi c outcome indicators and changes to the indicators of the state of biological invasions) and broader societal indicators for impact will be a major focus of future reports. In line with international proposals (GEO BON, 2015, Latombe et al., 2017), the status reported should be modular. If resources permit, high-level data can be collected without compromising the ability to compare with situations where fewer data or resources are available. For example, accurate distribution data are available for birds, but not for microbes (Chapter 4). Sniff er dogs are frequently used to detect illegal imports, including alien species 17 CHAPTER 2 I INDICATORS 2.3. CONFIDENCE LEVELS Indicators are, of course, abstractions of the real world and the real world does not always fi t neatly into these abstractions. There will be some uncertainty in any values presented whether because of how they were measured or that the subjects of measurement themselves are variable. This report follows broad guidelines used in related environmental assessments and classifi es confi dence level of any of the assessments into three broad categories (Table 2.1). TABLE 2.1 Guidance regarding the use of the confi dence rating [adapted from Hawkins et al., 2015, modifi ed from the EPPO pest risk assessment decision support scheme (Alan MacLeod 09/03/2011. revised 28/04/2011. copied from CAPRA, version 2.74; 2)]. Exact defi nitions are given for each indicator in Appendix 1. CONFIDENCE LEVEL DEFINITION HIGH There is direct relevant observational evidence to support the assessment; AND observations are at the relevant spatial or temporal scale; AND the data sources are reliable and of good quality; AND the interpretation of data and information is straightforward; AND data and information are not controversial or contradictory. MEDIUM There is some direct observational evidence to support the assessment, but some information is inferred; AND/OR observations are recorded at a spatial or temporal scale which may not be at the relevant scale but extrapolation or downscaling of the data is considered reliable, or to embrace little uncertainty; AND/OR the interpretation of the data is to some extent ambiguous or contradictory. LOW There is no direct observational evidence to support the assessment, e.g. only inferred data have been used as supporting evidence; AND/OR observations are recorded at a spatial or temporal scale which is unlikely to be relevant to the scale required, and extrapolation or downscaling of the data to relevant scales is considered unreliable or to embrace signifi cant uncertainties; AND/OR evidence is poor and diffi cult to interpret, e.g. because it is strongly ambiguous; AND/OR the information sources are considered to be of low quality or contain information that is unreliable. 18 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 2.4. INDICATORS USED IN THIS REPORT In this section, the indicators used in this report are defi ned in the context of the overall reporting framework (Figure 2.1). A complete set of indicators for pathways, species and areas, as well as interventions (eff ectiveness of control measures and eff ectiveness of regulations) are presented in the sections that follow. Further detail on each indicator is provided in Appendix 1, including the intended use and interpretation of the indicator, the implications of a change in the indicator, and the recommended format of presentation. In addition, Appendix 1 provides information on source data, specifi es the procedure to be followed when calculating the indicator’s value, and identifi es the units in which the indicator is expressed. Basic inventory and ecological research Assess implications and formulate appropriate policy Set goals and implement management measures Monitoring and evaluation Chapter 1: Introduction Chapter 8: Key Gaps Chapter 2: Indicators Chapter 9: Key messages Chapter 3: Pathways Chapter 4: Species Chapter 5: Areas INTERVENTIONS Chapter 6: Control measures Chapter 7: Regulations Outcomes Outputs Inputs FIGURE 2.1 The structure used in this report. Indicators are developed in this chapter for each of the fi ve subsequent chapters – pathways, species, areas, eff ectiveness of regulations, and eff ectiveness of control measures. The eff ectiveness of regulations and the eff ectiveness of control measures are considered jointly here as interventions, and are assessed in terms of indicators of inputs, outputs, and outcomes. In chapter 8 key gaps are identifi ed and, in chapter 9, based on the insights from the other chapters, recommendations for policy makers and managers are developed. The indicators do not, however, cover everything in the report. In particular, there are several additional factors that must be reported on in terms of the regulations, but do not directly infl uence the indicators for the outcomes of the interventions and in and of themselves do not provide information as to whether interventions are succeeding or not. There are also several enabling processes that are not discussed in this report (accessibility of data and information; organisational and human capacity; research; and public awareness and engagement). See section 8.3 for a discussion on how they might be incorporated into future reports. 2.4.1. Pathways This report considers four indicators for pathways (Table 2.2) that assess the prominence of the pathway and the rate at which taxa are introduced along the pathway, for both introduction into the country, and dispersal within the country: 1) introduction pathway prominence; 2) introduction rates; and the corresponding 3) within-country pathway prominence; and 4) within-country dispersal rates. 19 CHAPTER 2 I INDICATORS At a basic level, the indicators use the hierarchical scheme of pathway classifi cation adopted by the Convention on Biological Diversity (CBD), based on six broad categories and 44 sub-categories (Appendix 2; Scalera et al., 2016). If data are available, spatially explicit vectors can be used to facilitate precise response and management. Similarly at a basic level introduction rates are in terms of the number of alien species introduced, although ideally there would be estimates of colonisation and propagule pressure for each introduction event. TABLE 2.2 Indicators for reporting on the status of introduction and dispersal pathways (indicator values are estimated in Chapter 3). For full details of how to calculate the indicators, see Appendix 1. INDICATOR METRIC BASIC ADVANCED 1. Introduction pathway prominence 1.1. Five qualitative categories indicating the prominence of CBD pathway sub-categories (Not known; Pathway not present; Minor; Moderate; Major) 1.2. A ranked order of pathways in terms of their prominence 1.3. Spatially explicit vectors that detail the amount, number and value of goods or vessels moving into the country per pathway, with information on the sources, routes, destinations, and timings 2. Introduction rates 2.1. The total number of alien species introduced through each CBD pathway sub-category over all time 2.2. Five categories demonstrating changes over a recent period of time (e.g. since the 1980s or in the past decade) in the number of species introduced through each pathway (Not known; No introductions; Increase; Decrease; Minimal change) 2.3. Number of individuals of each species introduced through the pathways and place and date of introduction 3. Within-country pathway prominence 3.1.–3.3. As for 1. Introduction pathway prominence, for within-country dispersal rather than introductions 4. Within-country dispersal rates 4.1.–4.3. As for 2. Introduction rates, for within-country dispersal rather than introductions 2.4.2. Species This report uses species as the primary biological unit in line with the majority of the taxa listed under the National Environmental Management: Biodiversity Act, Alien and Invasive Species Regulations (the NEM:BA A&IS Regulations). However, several taxa are listed at levels other than species, invasions can occur at the gene level (e.g. resulting in the loss of indigenous species through hybridisation), and fundamentally biological invasions are a population level phenomenon. These issues might be a focus for future reports. The proposed system for global observation and monitoring of alien species identifi ed three essential variables for monitoring species – alien status, occurrence and impact (Latombe et al., 2017). In this report elements of determining alien status are combined with a very coarse categorisation for occurrence (5. Number and status of alien species). If a species is present and clearly alien, the next part of defi ning status is to determine where it is, and how common it is (indicators 6. Extent of alien species; and 7. Abundance of alien species). Finally, in direct alignment with the proposed global scheme is indicator 8. Impact of alien species (Table 2.3). 20 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 For the Number and status of alien species, at a basic level this is simply the number of invasive species (as these are the primary focus of most management eff orts). At a more advanced level all alien species should be listed and placed into relevant categories along the introduction-naturalisation-invasion continuum (Blackburn et al., 2011), but in all cases there are two decisions to be made: 1) is a species alien or indigenous?; and if it is alien, 2) is it present in the region? The fi rst part, i.e. determining nativity, is often fairly straight-forward, but in the case of cosmopolitan species it might be impossible to trace the indigenous range, and for other taxa, (microbes and fungi in particular) determining indigenous ranges requires extensive sampling and molecular analysis with little guarantee of success (Wood, 2017). Determining presence can be straightforward in many cases, but highly problematic in others. The minimum standards required for a species to be included on a list of alien species vary between lists, and in many cases no physical specimen is required. Similarly there is often, at least historically, no requirement or legal mechanism whereby deliberately introduced species needed to be recorded. Import permits alone are not suffi cient proof of presence as permits can be issued, but not actually used. Moreover alien species, even those that have established, do not always persist (Simberloff & Gibbons, 2004). For example, Tetrapygus niger (black sea urchin) was recorded in South Africa in 2007, but the area where it was present has been transformed. Based on a recent survey, the species is considered to no longer be present in the country (Mabin, Wilson & Robinson, 2015). This points to the need to document when, where, and on what basis, the presence of a taxon was noted. Similarly, the evidence for declaring that a species is absent needs to be made clear. Such information is important for policy, as it is a key determinant when evaluating applications to import species. By their nature, lists of alien species are dynamic as taxa are introduced, naturalise, become invasive, disappear from an area, or are eradicated. There are a few additional issues that mean lists change over time, e.g. cryptic taxa are identifi ed as aliens, or there are taxonomic changes (Jacobs et al., 2017, Pyšek et al., 2013). Consequently, lists need to be dynamic, and changes need to be clearly documented based on defi ned minimum standards (Murray et al., 2017). The level of confi dence that any particular species is still present should decline with time since the last specimen was collected or the last recorded fi eld sighting. In terms of alien species distributions, the Extent of alien species can be assessed using occupancy at broad spatial scales. At the broadest scale this will be occupancy at provincial, biome, primary catchment scale or marine ecoregion, but data are often available at a quarter-degree grid cell (~630–710 km2 at the latitude of South Africa) and so this is used here. The measure of the Abundance of alien species will vary depending on the type of organism. For mobile taxa this might be an estimate of numbers of individuals, while for sessile organisms it might be a measure of how much of the area is occupied at a fi ne scale (i.e. condensed canopy area). These data are, of course, not always available or the data are insuffi cient to provide reliable estimates. Therefore a categorical approach might be needed (e.g. rare, occasional, or abundant). Data for extent and abundance come from physical collections, mapping (atlas) projects and dedicated surveys. Each method has its own strengths and biases (Robinson, Cumming & Erasmus, 2010), and therefore aff ect the confi dence level with which estiamtes are given. Finally, the Impact of alien species needs to be measured both in environmental and socio-economic terms. Recently, there has been substantial progress in developing consistent metrics that can be used to score the impacts of particular alien taxa, in particular through the Environmental Impact Classifi cation for Alien Taxa (EICAT) scheme (Blackburn et al., 2014, Hawkins et al., 2015) that has recently been adopted by the IUCN and the more recent Socio-Economic Impact Classifi cation of Alien Taxa Scheme (SEICAT; Bacher et al., 2018). EICAT provides a consistent method for rating impact as minimal, minor, moderate, major or massive, with interpretations 21 CHAPTER 2 I INDICATORS provided for diff erent impact mechanisms (for example competition, predation or herbivory, or chemical, physical or structural features of the ecosystem). The accurate assessment of species within this system requires confi rmation that the species is alien, and the availability of adequate data to confi dently place the species into one of the rating categories. SEICAT is similar in structure, with impacts measured in terms of how alien species aff ect what people do. TABLE 2.3 Indicators used for reporting on the status of alien species (indicator values are estimated in Chapter 4). For full details of how to calculate the indicators, see Appendix 1. INDICATOR METRIC BASIC ADVANCED 5. Number and status of alien species 5.1. Number of invasive species 5.2. Number of alien species in one of three categories (alien but not naturalised, naturalised but not invasive, invasive) 5.3. Number of species in each of the 12 diff erent stages identifi ed in the Unifi ed Framework for Biological Invasions 6. Extent of alien species 6.1. Number of large-scale national subdivisions (provinces, primary catchments or bioregions as appropriate) occupied per species 6.2. Number of fi ner-scale national subdivisions (quarter-degree grid cells or hectads) occupied per species 6.3. Range size for each species (e.g. km2 or ha) 7. Abundance of alien species 7.1. Categorical measure of abundance per species in one of fi ve categories (absent, rare, occasional, abundant, not known) 7.2. Number of individuals for mobile organisms or condensed area occupied for sessile organisms 7.3. Abundance estimates divided into appropriate stage or age cohorts. At a basic level numbers of individuals which are reproductive or not 8. Impact of alien species 8.1. Categorical factor with eight levels. A single value is presented which is the maximum current recorded impact in South Africa in terms of either the Environmental Impact Classifi cation of Alien Taxa (EICAT) or Socio-economic Impact Classifi cation of Alien Taxa (SEICAT) schemes (Bacher et al., 2018, Blackburn et al., 2014) 8.2. The current and maximum ever recorded EICAT and SEICAT scores for each possible impact mechanism for each species in South Africa 2.4.3. Areas There are a variety of ways to categorise areas. While administrative regions are useful for management, they do not necessarily follow biogeographical zones. But even biogeographical zones, as defi ned by the presence of indigenous species, are not necessarily useful or appropriate as the processes that set biogeographic boundaries can diff er from those that determine spatial patterns for alien species (Rouget et al., 2015). As such, areas are often defi ned for practical planning reasons, e.g. municipalities or national parks, or a simple grid is used, e.g. quarter degree grid cells [QDGCs, often also (incorrectly) called quarter degree squares, QDSs]. In South Africa tertiary catchments are also frequently used (e.g. Roux et al., 2008), but while perhaps more ecologically relevant, this is not the scale at which data on biological invasions in the country has been collected. Therefore in this report two levels are considered: broad scale (provinces, biomes, marine regions, or primary catchments as appropriate) and QDGCs. These scales are largely dictated by the availability of data. 22 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 The fi rst indicator is simply the total number of alien species in a given area (9. Alien species richness, Table 2.4). At a basic level this is the number of invasive species (as data are mostly collected on invasive species rather than those in captivity or cultivation and the invasive species are usually those of most direct concern). At more advanced levels, the number of alien species at diff erent stages of the Unifi ed Framework is reported on. The assumption is generally made that if a species is invasive in one area and recorded in another it is also invasive there, but this would require some refi nement and ideally area-specifi c assessments of introduction status are required. While Alien species richness provides a useful measure of the invasions, it does not take into account overall diff erences in species richness in an area. Therefore, Catford et al. (2012) recommend additional relative measures, codifi ed here as 10. Relative alien species richness and 11. Relative invasive abundance (Table 2.4). The relationship between Relative alien species richness and Relative invasive abundance can indicate the presence of dominant invasive species and the trajectory of invasion over time (Catford et al., 2012). In this report, the distinction is made between Relative alien species richness and Relative invasive species abundance, as the former can give an indication of the potential size of future problems (taking all alien species into account), but the latter is a metric of the current status of invasions. At a basic level Relative invasive abundance is measured qualitatively (i.e. not known; invasive-free; minor; moderate; extensive; dominant), but where data allow a quantitative measure of the total abundance is preferred (e.g. percentage of cover, biomass, or numbers of individuals). The importance of the Impact of invasions within a certain area will diff er depending on the area-type. For example, in protected areas with high indigenous biodiversity, the degree of threat to indigenous biodiversity would be the main critical indicator, whereas in other areas reduction in ecosystem services (in terms of benefi t fl ows and fi nancial fl ows) or impacts on human livelihoods would be more important. There is no accepted, unifi ed system for the classifi cation of the impacts of all biological invasions on a particular area. Nonetheless, several studies have quantifi ed the impact of particular invasions on the overall biodiversity of an area (e.g. Van Wilgen et al., 2008); and reductions in particular ecosystem services, expressed both in terms of benefi t fl ows (e.g. the amount of water fl owing from a catchment, or the number of livestock supported on a rangeland, Van Wilgen et al., 2008) or fi nancial fl ows (the value of the benefi ts in monetary terms, De Lange & Van Wilgen 2010). Finally, the eff ects of invasive species can be assessed in terms of their impact on human livelihoods in a given area (Shackleton et al., 2007). In the absence of other indicators, we propose to measure the Impact of invasions for particular areas of South Africa in terms of the reduction in water resources, grazing capacity and biodiversity (Table 2.4). Similar to the categories under the EICAT scheme, we propose that reductions in the service of < 2% are minor; 2–10% will be moderate; 10–50% will be major; and > 50% will be massive. These cut-off s are somewhat arbitrary and, unlike EICAT, they do not take the permanence of the change into account. We propose that a national status report should assess these reductions for particular ecosystem services for which at least some estimates have been made, or where models exist to make them. Based on an EICAT assessment, it should also be possible to convert information on species-impact status into the appropriate area-impact status for a target region. This is, however, clearly a topic where more work is required. It would be desirable to develop advanced indicators that could express the eff ects of reductions in ecosystem services in economic or social terms (De Lange & Van Wilgen, 2010), ideally again linking conceptually with the EICAT scheme. 29 CHAPTER 3 I PATHWAYS OF INTRODUCTION The introduction and dispersal of alien species are infl uenced by a number of interacting variables (including the environment and species traits). In particular, trends in socio-economic factors (e.g. management interventions, fashions, economic conditions) play an important role in shaping the pathways of introduction and dispersal, and determining how they change over time (Hulme et al., 2008; Essl et al., 2011, 2015a; Ojaveer et al., 2017; Saul et al., 2017; Seebens et al., 2017; Zieritz et al., 2017). For example, changes to global energy markets might result in an increase in the number of marine species introduced to the USA through the release of ballast water (Holzer et al., 2017); and while acclimatisation societies facilitated the release of many alien species in New Zealand, Australia and the USA, a decrease in the public and scientifi c support for these societies during the twentieth century led to a decrease in these activities (Seebens et al., 2017). It is, therefore, important to understand the potential pathways of introduction and the role they play, as well as how important they might be for the introduction of alien organisms. The four indicators developed to track these factors are: (1) Introduction pathway prominence, (2) Introduction rates, (3) Within-country pathway prominence, and (4) Within-country dispersal rates (Table 2.2). Introduction and Within-country pathway prominence consider the size of the pathways of introduction and dispersal but do not take into account the importance of the pathways for the introduction or dispersal of alien organisms. Introduction rates and Within-country dispersal rates consider the importance of the pathways for the introduction and dispersal of new alien organisms. Information on how these indicators have changed over time and forecasts of future changes not only inform the development of policies and management strategies but are vital when evaluating the eff ectiveness of pathway-related control measures. The status of the pathways of introduction in South Africa and how they have changed over time has been recently assessed using historical introduction data (see Faulkner et al., 2016a). Building on this work, this report refi nes the analysis using the pathway categorisation scheme adopted by the CBD, and historical introduction and socio-economic data were obtained to populate the four indicators discussed above. These indicators were used to evaluate current pathway status and historical changes to the pathways, and where possible, socioeconomic forecasts were obtained to get an indication of how these pathways might change in future. Finally, the eff ectiveness of pathway related control measures is evaluated and sources of uncertainty addressed (including knowledge gaps). The eff ectiveness of pathway related control measures and regulations are discussed in Chapter 6 and 7 respectively. Facility for mass-rearing biological control agents – Kim Weaver 30 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 MECHANISM OF ENTRY PATHWAY CATEGORY PATHWAY SUBCATEGORY IR CHANGE IN IR IPP FORECAST CONTROL INCREASING HUMAN ROLE Biological control 111 Mod E Erosion control/dune stabilisation 68 NK NK NK NK Fishery in the wild 15 X Maj NK E Release in nature Hunting 30 Mod /N/I Landscape/fl ora/fauna “improvement” in the wild 8 X PNP – P Introduction for conservation purposes or wildlife management 0 X NK NK NK Release in nature for use other than above 8 NK NK NK NK Other intentional release 0 X NK NK NK Agriculture 91 NK Maj NK Aquaculture/mariculture 12 X Min E Botanical garden/zoo/aquaria 3 X Min NK E Pet/aquarium/terrarium species 22 – Min NK N/I Farmed animals 5 X Maj NK E COMMODITY Escape from confi nement Forestry 30 NK Maj NK NK Fur farms 1 X Min NK E Horticulture 237 NK Mod NK Ornamental purpose other than horticulture 1 X NK NK E Research and ex-situ breeding 4 NK Min NK NK Live food and live baits 5 X NK NK E Other escape from confi nement 72 NK NK NK NK Contaminant nursery material 3 NK Mod NK NK Contaminated bait 0 X NK NK NK Food contaminant 7 NK Maj NK NK Contaminant on animals 9 – Maj NK N/I Transport– Contaminant Parasites on animals 13 – Maj NK N/I Contaminant on plants 20 – Mod NK N/I Parasites on plants 2 – Mod NK N/I Seed contaminant 8 NK Mod NK NK Timber trade 10 NK Maj NK NK Transportation of habitat material 6 – NK NK N/I Angling/fi shing equipment 0 X Maj N/I Container/bulk 0 X Mod NK Hitchhikers in or on airplane 5 NK Mod NK Hitchhikers on ship/boat 21 – Mod N/I TRANSPORT VECTOR Transport– Stowaway Machinery/equipment 0 X NK NK N/I People and their luggage/equipment 0 X Maj NK Organic packing material, in particular wood packaging 1 NK NK NK NK Ship/boat ballast water 51 – Mod N/I Ship/boat hull fouling 68 Mod N/I Vehicles 1 NK Maj NK N/I Other means of transport 0 X NK NK N/I NATURAL SPREAD Corridor Interconnected waterways/basins/seas 0 X Min – N/I Tunnels and land bridges 0 X Min – N/I Unaided Natural dispersal across borders of invasive alien species that have been introduced through pathways 1 to 5 9 – Maj N/I F IGURE 3.1 The current and forecasted status of the pathways of introduction and the eff ectiveness of control measures. IR:rates of introduction for the pathways (i.e. number of taxa introduced over all time), Change in IR: changes to the rate of introduction in the last full decade in comparison to that of the previous decade (NK: not known;  increase;  decrease; – minimal change; X no introductions), IPP: introduction pathway prominence (NK: not known; PNP: pathway not present; Min: minimal; Mod:moderate; Maj:major), forecasted changes to introduction pathways (NK: not known;  increase;  decrease; – minimal change;  /  increase or decrease), and the eff ectiveness of control measures (NK: not known; N/I: none/ineff ective; E: Eff ective; P:Permanent). The pathways were categorised using the scheme adopted by the Convention on Biological Diversity (CBD, 2014). For details see section 3.5 and Table A2.1. 31 CHAPTER 3 I PATHWAYS OF INTRODUCTION 3.2. DATA SOURCES Intro duction and Within-country pathway prominence were assessed using socio-economic information collected from a wide range of sources. Information on the pathways of introduction, date of introduction and region of origin for taxa introduced to South Africa were obtained from the dataset presented in Faulk ner et al. (2015) and were used to assess Introduction rates. Information on the species dispersing through the pathways of dispersal was obtained from the literature and used to assess Within-country dispersal rates. Socio-economic data were obtained from a number of sources in order to forecast future changes to the pathways of introduction. All data sources are shown in Table 3.1. TABLE 3.1 Data sources used in the assessment of the status of the pathways of introduction and dispersal for South Africa. Sources with an asterisk (*) contributed to the dataset presented in Faulk ner et al. (2015). DATA SOURCE SCALE OF COVERAGE DESCRIPTION LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATOR INFORMED BY THESE DATA ACSA passenger and aircraft statistics (Airports Company South Africa, 2017) National Socio-economic information on air traffi c High 1. Introduction pathway prominence 3. Within-country pathway prominence Agricultural Research Council-Plant Protection Research Institute (2017) Continental Information on the introduction and spread of Spodoptera frugiperda in Africa (note: given its recent introduction this species is not included in the species lists in Appendix 3) Medium 2. Introduction rates Appleton (2003)* National Historical introduction data for freshwater molluscs Medium 2. Introduction rates Bromilow (2010)* National Historical introduction data for plants Medium 2. Introduction rates CITES trade database (UNEP World Conservation Monitoring Centre, 2017) Global Socio-economic information on the number of animals imported for personal use, botanical garden/zoo purposes and scientifi c purposes Low 1. Introduction pathway prominence Cock et al. (2016) Global Information on insects released to biologically control other insects High 2. Introduction rates DAFF Diagnostic Import Interception Database (Department of Agriculture, Forestry and Fisheries, 2017) National Interception data for imported plants, food, seed and habitat material Medium 2. Introduction rates De Moor & Bruton (1988)* Regional Historical introduction data for freshwater fi sh, Ciliophora, Cnidaria and Platyhelminthes Medium 2. Introduction rates Dean (2000)* Regional Historical introduction data for birds, as well as information on dispersal for Corvus splendens Medium 2. Introduction rates 4. Within-country dispersal rates Department of Agriculture, Forestry and Fisheries (2015) National Socio-economic information on seed imports and production High 1. Introduction pathway prominence Department of Agriculture, Forestry and Fisheries (2016a) Continental Information on the introduction and spread of Tuta absoluta in Africa Medium 2. Introduction rates Department of Agriculture, Forestry and Fisheries (2016b) Continental Information on the introduction and spread of Tuta absoluta in Africa Medium 2. Introduction rates 32 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 DATA SOURCE SCALE OF COVERAGE DESCRIPTION LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATOR INFORMED BY THESE DATA Department of Home Aff airs (2017) National Information for South African ports of entry High 1. Introduction pathway prominence Department of Transport (2016) National Socio-economic information on South African airports High 1. Introduction pathway prominence Dippenaar-Schoeman & Harvey (2000)* National Historical introduction data for Arachnida Medium 2. Introduction rates FAO (2016a) Global Socio-economic information on fi shing Medium 1. Introduction pathway prominence FAOSTAT database of the Food and Agriculture Organisation of the United Nations (FAO, 2017) Global Socio-economic information on food imports and on the agriculture, livestock farming and forestry sectors Medium 1. Introduction pathway prominence FishstatJ database of the Food and Agriculture Organisation of the United Nations (FAO, 2016b) Global Socio-economic information on the fi shing and aquaculture sectors Medium 1. Introduction pathway prominence Fur Free (2017) National Socio-economic information on fur farming Low 1. Introduction pathway prominence Germishuizen et al. (2006)* National Historical introduction data for plants Medium 2. Introduction rates Guimapi et al. (2016) Continental Information on the introduction and spread of Tuta absoluta in Africa Medium 2. Introduction rates Henderson (2001)* National Historical introduction data for plants Medium 2. Introduction rates Herbert (2010)* National Historical introduction data for terrestrial molluscs Medium 2. Introduction rates Hurley et al. (2012) National Information on the introduction and dispersal of Sirex noctilio within South Africa Medium 4. Within-country dispersal rates IMF trade forecast statistics (International Monetary Fund, 2016) Global Socio-economic information on the volume of imported goods Medium 1. Introduction pathway prominence Klein (2011)* National Historical introduction data for biological control agents released to control alien plant species High 2. Introduction rates Leibold & Van Zyl (2008) National Socio-economic information on fi shing Medium 1. Introduction pathway prominence Lever (2005) Global Information on the spread of bird species within South Africa Medium 4. Within-country dispersal rates Long (1981) Global Historical introduction data for birds Medium 2. Introduction rates Long (2003)* Global Historical introduction data for mammals Medium 2. Introduction rates Martin & Coetzee (2011) National Information on the spread of aquatic plant species within South Africa High 4. Within-country dispersal rates Mead et al. (2011)* National Historical introduction data for marine taxa Medium 2. Introduction rates Measey et al. (2017) Regional Information on the dispersal and spread of amphibian species within South Africa High 4. Within-country dispersal rates Middleton (2015) National Socio-economic information on horticulture High 1. Introduction pathway prominence Moran, Hoff mann & Zimmermann (2013) National Information on the within-country dispersal of biological control agents High 4. Within-country dispersal rates OpenStreetMap contributors (2017) Global Spatial data on South Africa’s road and rail networks High 3. Within-country pathway prominence Picker & Griffi ths (2011)* National Historical introduction data for a wide variety of animals, including fi sh, birds, crustaceans, molluscs, insects and mammals. Information on the dispersal and spread of species within the country Medium 2. Introduction rates 4. Within-country dispersal rates 33 CHAPTER 3 I PATHWAYS OF INTRODUCTION DATA SOURCE SCALE OF COVERAGE DESCRIPTION LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATOR INFORMED BY THESE DATA Plisko (2010)* National Historical introduction data for Annelida Medium 2. Introduction rates Richardson et al. (2003) National Socio-economic information on horticulture. Information on the spread of fi sh species High 1. Introduction pathway prominence 4. Within-country dispersal rates Seebens et al. (2017) Global Information on global trends in the introduction of alien species Medium 1. Introduction pathway prominence 2. Introduction rates South African Government (2017) National Socio-economic information on fi shing Medium 1. Introduction pathway prominence StatsSA tourism and migration statistics (Statistics South Africa, 2017) National Socio-economic information on the number of people arriving in South Africa Medium 1. Introduction pathway prominence Taylor, Lindsay & Davies-Mostert (2015) National Socio-economic information on the hunting sector Medium 1. Introduction pathway prominence 3. Within-country pathway prominence Transnet National Ports Authority (2014) National Socio-economic information on shipping Medium 1. Introduction pathway prominence Transnet National Ports Authority’s Port statistics (Transnet National Ports Authority, 2017) National Socio-economic information on shipping High 1. Introduction pathway prominence United Nations Comtrade database (UN-Comtrade, 2017) Global Socio-economic data on live plant and vehicle imports Medium 1. Introduction pathway prominence Van Rensburg et al. (2011)* National Historical introduction data for freshwater fi sh, amphibians, birds, mammals and reptiles. Information on the fi shing, hunting and aquaculture sectors and the within-country dispersal of fi sh Medium 1. Introduction pathway prominence 2. Introduction rates 3. Within-country pathway prominence 4. Within-country dispersal rates Van Wilgen et al. (2010) National Socio-economic information on the import of animals as pets Medium 1. Introduction pathway prominence Visser et al. (2017a) National Information on the introduction of Tuta absoluta to South Africa Medium 1. Introduction pathway prominence Visser et al. (2017b) National Information on the current and historical introduction pathways for grasses Medium 1. Introduction pathway prominence WTO trade statistics (World Trade Organisation, 2017) Global Socio-economic information on merchandise imports Medium 1. Introduction pathway prominence WTTC’s tourism and travel statistics (World Tourism and Travel Council, 2017) Global Socio-economic information on travel and tourism Medium 1. Introduction pathway prominence Zachariades et al. (2017) National Information on biological control agents released to control alien plants and future plans for these programs High 1. Introduction pathway prominence 4. Within-country dispersal rates Zimmermann, Moran & Hoff mann (2004) National Information on biological control agents and their within-country dispersal High 4. Within-country dispersal rates 34 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 3.3. STATUS OF THE PATHWAYS 3.3.1. Status of the pathways of introduction Based on socio-economic data, many of the pathways of introduction appear to be playing an important role in South Africa and in many cases the prominence of these pathways has increased over time (see Figure 3.1 and Table A2.1). There are 72 offi cial ports of entry through which people, goods and transport vessels can enter the Republic. Eight of these are maritime ports, ten are airports and 54 are land border posts (Figure 3.2). The number of people entering South Africa through these ports of entry has increased over time, and in 2016 over 21 million people entered the country (Figure 3.3). According to the World Tourism and Travel Council (2017), over 10 million of these were tourists. Tourism and travel is an important industry in South Africa and the contribution this sector has made to Gross Domestic Product (GDP) has increased over time (Figure 3.4). The quantity of food imported into South Africa through the ports of entry has also increased over time, and in 2013 over 7 million tonnes of food was imported (Figure 3.5). These pathways are examples of many that are playing a major and increasing role in South Africa, and as alien taxa could be transported into the country within the luggage of tourists, or as contaminants of imported food, these pathways, along with a number of others, might be playing an important and increasing role in the introduction of alien organisms. FIGURE 3.2 South African ports of entry. Any person, who wishes to enter into or depart from South Africa, can only legally do so through these ports. Information was obtained from the South African D epartment of Home Aff airs (2017). 35 CHAPTER 3 I PATHWAYS OF INTRODUCTION AIR TRANSPORT Year 20162006 0 1 2 3 4 5 6 Number of arrivals (millions) ROAD TRANSPORT Number of arrivals (millions) Year 20162006 0 2 4 6 8 10 12 14 16 18 SEA TRANSPORT Number of arrivals Year 20162006 0 10 000 20 000 30 000 40 000 50 000 60 000 70 000 FIGURE 3.3 The number people arriving in South Africa by air, road and sea transport in 2006 and 2016. Data were obtained from St atistics South Africa (2017). 2009 2011 2013 2015 2017 2019 2021 2023 2025 2027 2007 Year 45 Contribution to GDP (billions of US dollars at real prices) 40 35 30 25 20 15 10 5 0 1995 1997 1999 2001 2003 2005 FIGURE 3.4 The contribution of travel and tourism to South Africa’s Gross Domestic Product has increased over time and is expected to continue to increase in the future. Data were obtained from the Wor ld Tourism and Travel Council (2017). Year 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2011 2013 2005 2007 2009 Quantity of imported food (million tonnes) 7 8 6 5 4 3 2 1 0 FIGURE 3.5 The quantity of food imported into South Africa has increased, particularly since 2000. Data were obtained from the Food and Agricultural Organisation of the United Nations (FAO , 2017). 36 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 As many introduction pathways are prominent in South Africa, it is not surprising that alien taxa have been intentionally and accidentally introduced to the country through a wide variety of introduction pathways. Although most alien taxa have been intentionally imported for the ornamental plant trade and then have escaped from gardens (Figure 3.1, Figure 3.6 and Figure 3.7), many have also been released for biological control or have been introduced for agriculture (Figure 3.1 and Figure 3.7). Although most alien taxa have been intentionally imported into the country, a large number have also entered the country accidentally (Figure 3.6). For example, many alien taxa have been introduced as contaminants on imported plants, or as stowaways on visiting ships (Figure 3.1 and Figure 3.7). Organisms that have been introduced to South Africa’s neighbouring countries have also spread into the country; however, no alien taxa are known to have spread into South Africa through human-built transport infrastructure that connects previously unconnected regions (Figure 3.1 and Figure 3.6). Pathway of introduction Release in nature Escape from Confi nement Transport– Contaminant Transport– Stowaway Corridor Unaided Unknown 0 500 1000 1500 Number of introduced taxa FIGURE 3.6 Number of alien taxa introduced to South Africa through the pathways of introduction (following the categorisation scheme adopted by the Convention on Biological Diversity), and the number of taxa for which pathway of introduction was unknown. RELEASE IN NATURE Number of introduced taxa Biological control Erosion control/ dune stabilisation Fishery in the wild Hunting Landscape/fl ora/ fauna improvement Conservation purposes or wildlife management Release in nature for use Other intentional release Not enough detail 0 100 200 ESCAPE FROM CONFINEMENT Number of introduced taxa Agriculture Aquaculture/ mariculture Botanical garden/zoo/ aquaria Pet/aquarium/ terrarium species Farmed animals Forestry Fur farms Horticulture Ornamental purpose other than horticulture Research (in facilities) Live food and live baits Other escape from confi nement Not enough detail 0 100 200 TRANSPORT – CONTAMINANT Number of introduced taxa Contaminant nursery material Contaminated bait Food contaminant Contaminant on animals Parasites on animals Contaminant on plants Parasites on plants Seed contaminant Timber trade Transportation of habitat Not enough detail 0 100 200 TRANSPORT – STOWAWAY Number of introduced taxa Angling/Fishing equipment Container/bulk Hitchhikers in or on airplane Hitchhikers on ship/boat Machinery/ equipment People and their luggage Organic packing material Ship/boat ballast water Ship/boat hull fouling Vehicles Other means of transport Not enough detail 0 100 200 Pathway of introduction FIGURE 3.7 Number of alien taxa introduced to South Africa through the pathways of introduction, and the number for which designation at the pathway subcategory level was not possible due to insuffi cient information. The graphs show the results for the pathway subcategories of the (from top to bottom) ‘Release in nature’, ‘Escape from confi nement’, ‘Transport – Contaminant’ and ‘Transport – Stowaway’ pathway categories. Results for the unaided pathway are not shown (see Figure 3.6 for the results of this pathway). 37 CHAPTER 3 I PATHWAYS OF INTRODUCTION Although data were insuffi cient for many of the pathways of introduction, for some pathways data were suffi cient to evaluate recent changes to the rate of introduction, and to assess the eff ectiveness of control measures. For eleven pathways, between 2000 and 2009 there was either a minimal change or an increase to the rate of introduction in comparison to that of the previous decade (Figure 3.1). Therefore, although control measures were enacted for some pathways in the 1980s, for many pathways the rate of introduction has not declined (Figure 3.1, also see Box 3.1 for an example). The rate at which alien taxa have been introduced to South Africa has declined for only one pathway: biological control (Figure 3.1). Regulatory process complications caused a decline in the number of taxa introduced for the biological control of invasive plants (Klein , 2011; Klein et al., 2011), while the number of insects released to control insect pests has also declined since the 1980s (Cock et al., 2016). Overall the introduction of biological control agents was, therefore, lower in the 1990s and 2000s than in the 1980s (see Figure A2.4). As the complications in these regulatory processes have since been resolved, and as biological control research and implementation for alien plants has recently increased (Zacha riades et al., 2017), it is likely there will be an increase in the release of biological control agents in the future (Figure 3.1). There have been no new alien taxa introduced for fi shing or aquaculture since the 1980s (Figure 3.1; also see Figure A2.4 and Figure A2.5). While this d ecline might be due to the control measures that were implemented during this period [i.e. Animal Diseases Act (Act No. 35 of 1984)], changing fashions or other socio-economic factors could also have played a role. During the last full decade (2000–2009), the annual rate of introduction has fl uctuated, with an average of 7 taxa introduced per year (Figure 3.8). Overall, and despite the control measures that are in place, the rate of introduction appears to be increasing (Figure 3.9). Year Number of taxa introduced per year 2005 2006 2007 2008 2009200420012000 0 5 10 15 2002 2003 FIGURE 3.8 The number of taxa introduced to South Africa during each year in the last full decade. 38 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 Number of introduced taxa Time period 0 20 40 60 80 100 1950-19591960-1969 1970-1979 1980-1989 1990-1999 2000-2009 2010-2019 FIGURE 3.9 The number of taxa introduced to South Africa during each decade since the 1950s. Data for 2010 to 2019 were incomplete and are shaded in grey. 3.3.2. Status o f the pathways of dispersal Within-country pathway prominence is currently not known for all pathways of dispersal, in part as data are widely dispersed and owned by a number of diff erent entities. South Africa, however, has extensive transport networks (Figure 3.10) that facilitate the movement of goods and people around the country. In line with international trade patterns, the volume of goods and the number of people moving around the country is expected to increase. For instance, the number of domestic airline passengers has increased over time – such that in the 2015/2016 fi nancial year, there were over 13 million trips made on over 140000 fl ights (Figure 3.11). Importantly, not all of the species moving within the country are alien to the Republic, and species that are indigenous to one part of the country can also be transported and introduced to parts of the country where they are not indigenous (Measey et al., 2017). Alien and indigenous species that are sold at pet stores (Figure 3.12) are often traded (e.g. through private or public sales on web-sites like Ebay) and moved around the country by members of the public (Martin & Coetzee, 2011, Measey et al., 2017). Similarly alien and indigenous fi sh are often transported and introduced into new river systems by anglers (Picker & Griffi ths, 2011). Many alien taxa have also become widely dispersed through natural spread [e.g. Sturnus vulgaris (the common starling) was introduced to the Western Cape and spread north (Picker & Griffi ths, 2011)], but alien organisms are also transported as contaminants of commodities or as stowaways along the country’s extensive transport networks (Figure 3.10). For example, Sirex noctilio (sirex woodwasp) was probably imported and transported around the country in infested timber (Picker & Griffi ths, 2011; Hurley et al., 2012). Organisms are also known to have spread within the country through human made transport infrastructure that connects previously unconnected areas. For example, fi sh species have dispersed along canals and pipes used to transfer water between river basins (Richards on et al., 2003; Van Rensburg et al., 2011). 45 CHAPTER 3 I PATHWAYS OF INTRODUCTION INDICATOR VALUE BASIC ADVANCED LEVEL OF CONFIDENCE NOTES 2. Introduction rates 2.1. 0 taxa: 10 pathways 1 – 50 taxa: 27 pathways 51 – 100 taxa: 5 pathways > 100 taxa: 2 pathways 2.2. Increase: 2 pathways Decrease: 1 pathway Minimal change: 9 pathways No introductions: 18 pathways Not known: 14 pathways 2.3. Data not available 2.1. Low 2.2. Low Pathway and date of introduction data are not available or have not been collated for many alien taxa in South Africa 3. Within-country pathway prominence 3.1. Data not available 3.2. Data not available 3.3. Data not available N/A Data were only collected for a few pathways 4. Within-country dispersal rates 4.1. Data not available 4.2. Data not available 4.3. Data not available N/A Pathway and date of dispersal data have not been collated for alien taxa in South Africa A. Rate of introduction of new unregulated species A. 7 taxa per year A. Low Date of introduction data are not available for many alien taxa in South Africa BOX 3.1 THE LIVE PLANT TRADE AS A PATHWAY FOR INTRODUCING CONTAMINANTS. Live plants and their products are imported into South Africa for a number of uses. For example, as South African consumers in the ornamental plant sector show a desire for new varieties of plants, plants are often imported for this purpose (Middleton, 2015). Live plant imports to South Africa have increased over time and in 2016 these imports were valued at over 12million US dollars (UN-Comtrade, 2017). To meet the requirements of the International Plant Protection Convention, South African phytosanitary policies require that all plant imports must be inspected in the country of origin, treated with pesticides and declared free of any organisms before import (Saccaggi & Pieterse, 2013). Despite this, organisms are often found on imported plants and plant products when inspected at South African ports of entry (Saccaggi & Pieterse, 2013). Additionally, over 20 species have been introduced as contaminants or parasites of plants, and the rate at which these organisms have been introduced has remained consistent over time (Figure 3.1; also see Table A2.1). For example, Linepithema humile (Argentine ant) is believed to have been introduced to South Africa as a contaminant of imported horse fodder (Picker & Griffi ths, 2011). Once imported, plants are intentionally transported and sold throughout the country (Martin & Coetzee, 2011), and their contaminants are potentially transported with them. The live plant trade is, therefore, an important and potentially increasing pathway through which alien organisms are introduced to the country, but this trade also likely facilitates the dispersal of alien taxa within the country after introduction. 46 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 BOX 3.2 HULL FOULING AS A PATHWAY OF INTRODUCTION FOR MARINE ORGANISMS. Photographer: T. Robinson South Africa has eight major maritime ports (Richards Bay, Durban, East London, Ngqura, Port Elizabeth, Mossel Bay, Cape Town and Saldanha Bay), and in 2016 over 8000 ocean going vessels arrived at these ports (Transnet National Ports Authority, 2017). Ships can facilitate the introduction of alien taxa in a number of ways. Marine organisms can be transported within the ballast water carried by ships or can attach to ships’ hulls. Through these pathways ships have facilitated the introduction of many marine taxa to South Africa (Figure 3.1). In September 2017, the International Maritime Organisation’s (IMO) ‘International Convention for the Control and Management of Ships’ Ballast Water and Sediments’ entered into force (IMO, 2004). This convention aims to prevent the transportation of aquatic organisms between regions, and under the convention all ships are required to manage their ballast water and sediments to a certain standard. South Africa has also drafted ballast water legislation (Marine Draft Ballast Water Bill), but this legislation has not yet been passed. Although there are, therefore, plans to manage the introduction of marine organisms through the release of ballast water by ships, there are currently no plans or management in place to prevent introductions through hull fouling. Over 60 alien taxa are believed to have been introduced to South Africa attached to the hulls of visiting ships, and the rate at which these introductions have occurred has increased over time (Figure 3.1; also see Table A2.1). Furthermore, to deal with increasing demand, all of South Africa’s major ports, except Mossel Bay, will be upgraded and expanded in the future (Transnet National Ports Authority, 2014). This action could lead to an increase in the number of visiting ships, and unless additional biosecurity measures are put in place, the increased shipping intensity could result in an increase in the introduction of marine organisms through hull fouling. The threat posed by this pathway is, however, not simply in proportion to the number of visiting ships, and is higher for particular ports (Durban in particular) and for particular trade routes (routes from Asia) (Faulkner et al., 2017b). 4 THE STATUS OF ALIEN SPECIES Lead authors: Brian van Wilgen, Tendamudzimu Munyai, Zanele Mnikathi, John Wilson Contributing authors: Tumelo Morapi, Lee-Anne Botha, Therese Forsyth, Dai Herbert, Ian Rushworth, Llewellyn Foxcroft, Heather Terrapon, Andrew Turner, Rob Little, Michelle Greve, John Measey, Tammy Robinson, Charles Griffi ths, Pat Holmes, Siyasanga Miza Chapter summary This chapter provides an overview of the status of alien species in South Africa based on data from a wide range of sources (atlas projects, expert assessments, lists, and published papers and reports). Of the 2033 alien species recorded (or assumed to be present) outside of cultivation or captivity in South Africa, 775 are known to be invasive, 388 are known to be naturalised but not invasive, and 355 are present, but not naturalised. For the remainder (516 species), there is insuffi cient information to assign them to an introduction status category. Eight of the alien species recorded as present in the country are currently listed in the NEM:BA regulations as prohibited (i.e. species assumed to be absent from South Africa and which may not be imported). Large numbers of alien species have relatively restricted distributions. Only in the case of plants and birds are there widespread species [e.g. found in at least a quarter (i.e. > 500) of the quarter-degree grid cells (QDGCs) of South Africa]. At least one alien reptile and two terrestrial invertebrate species are relatively widespread (> 100 QDGCs), although the data coverage is poor, so there is a low level of confi dence in these estimates. The only data available to estimate the abundance of alien species are those for terrestrial and freshwater plants. These estimates are very crude or over 20 years out of date, so the level of confi dence in these estimates is very low. There are no comparable data for any other high-level taxa. A systematic evaluation of the impacts of individual invasive species as per the recently developed international standards has not yet been conducted. However, 25 species were assessed by experts as having a severe impact, and 82 as having a major impact. Of these 107 species, most (80) are terrestrial or freshwater plants, eight are mammals, fi ve each are freshwater fi sh, freshwater invertebrates and terrestrial invertebrates, two are amphibians, and there is one bird and one marine plant species. Alien plants are the most diverse, widespread and damaging group of invaders in South Africa. Furthermore, it is clear that South Africa has a major alien plant invasion debt. Well over 100 new taxa have been recorded as naturalised or escapes from cultivation over the past decade, and the recorded range of almost all plants has increased signifi cantly. This is a signifi cant cause for concern, as it clearly indicates that problems associated with alien species are set to increase. Tephrocactus articulates (pine cone cactus) – SANBI 48 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 4.1. INTRODUCTION This chapter provides an overview of the numbers, extent, abundance and impact of alien species in South Africa. The number of species was estimated using the list in the NEM:BA A&IS Regulations as a starting point, and adding other (unlisted) species that have been reported as naturalised in South Africa. The relevant indicators are the Number and status of alien species (i.e. whether they are known to be present in South Africa and their stage of introduction); the Extent of alien species (at national, provincial, biome or other scales); the Abundance of alien species status (in terms of their cover, biomass or population sizes); and the Impact of alien species (the degree to which the species has negative impacts). See Table 2.3 for further details. Data were obtained from a variety of sources (Table 4.1). These data were of varying quality, and this aff ected the level of confi dence placed in each indicator. In addition, the available data covered some, but not all, of the information needed to assign values to indicators, and for some indicators it is not yet possible to assign values due to a lack of data (Table 4.2). TABLE 4.1 Sources of data used to assign values to species indicators, with levels of confi dence based on the completeness and accuracy of data sets. Source Institutions for data: Animal Demography Unit (ADU); Centre for Invasion Biology (C•I•B ); KwaZulu-Natal Museum (KZN Museum); Plant Protection Research Institute of the Agricultural Research Council (ARC-PPRI); South African Institute of Aquatic Biodiversity (SAIAB); South African National Biodiversity Institute (SANBI); South African National Parks (SANParks); Stellenbosch University (SU); University of Cape Town (UCT); University of KwaZulu-Natal (UKZN); University of Pretoria (UP). The numbering of indicators is based on Chapter 2: 5. Number and status of alien species; 6. Extent of alien species; 7. Abundance of alien species; 8. Impact of alien species. TAXON SOURCE (SEE FOOTNOTE*) TOTAL NUMBER OF SPECIES DESCRIPTION LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATOR INFORMED BY THESE DATA All Cape Nature Totals provided for individual protected areas; no estimate of numbers across all protected areas Lists maintained for individual protected areas Moderate to low, depending on the protected area. Some protected areas have been poorly surveyed 5 All Dr Llewellyn Foxcroft, (C•I•B/ SANParks); Foxcroft et al. (2017)* 869 Lists maintained by SANParks High to low, depending on the park. Some are well-surveyed, others are data-poor 5, 6 All Dr Michelle Greve (UP) 47 Database of alien species occurring on the Prince Edward Islands. Moderate - conservative estimates as the invasion status of other alien species is unknown 5, 6, 8 All Ezemvelo KZN Wildlife Totals per protected area; no estimate of total across all protected areas Lists maintained for individual protected areas Moderate to low, depending on the protected area. Some protected areas have been poorly surveyed 5 species have major impacts according to experts 107 most (80) are terrestrial or freshwater plants 8 are mammals 1 marine invertebrate 5 each are freshwater fi sh, freshwater invertebrates & terrestrial invertebrates 1 is a bird species 2 are amphibians THE SITUATION 49 CHAPTER 4 I THE STATUS OF ALIEN SPECIES TAXON SOURCE (SEE FOOTNOTE*) TOTAL NUMBER OF SPECIES DESCRIPTION LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATOR INFORMED BY THESE DATA All NEM:BA A&IS species list 556 taxa are listed, but the number of species is larger as the regulations sometimes include genera with several species. Alien plant and animal species listed as invasive in the NEM:BA A&IS Regulations, or prohibited species found to be present in South Africa. Moderate – many listed species are not assigned to the correct categories, are not invasive, or have not been recently recorded in South Africa 5 All Zengeya et al. (2017)* 552 A simple scoring system was used to classify the alien species according to the relative degree of their benefi ts and negative impacts. Low 8 Amphibians; Reptiles Ditsong National Museum of Natural History Collection (Manamela, 2016) 49 Ditsong National Museum of Natural History Collection containing Herpetology, Mammal and Bird records from 1805 to 2008 Low – based on point data and does not include absence records 5, 6 Amphibians; Reptiles Dr John Measey (C•I•B, SU); Kumschick et al. (2017); Measey et al. (2017); Bates et al. (2014); Minter et al. (2004) 44 Spatial database (Frog and reptile atlases) housed at the ADU, UCT High for amphibians Moderate for reptiles 5, 6, 8 Animals Picker & Griffi ths (2017)* 571 Comprehensive listing of alien animal species in South Africa Low 5, 6 Birds Dr Rob Little (ADU/ UCT) 49 Spatial database (Bird atlas) housed at the ADU, UCT High – monitoring of distribution is frequent and the coverage is extensive 5, 6 Birds; Terrestrial invertebrates Faulkner et al. (2017a)* 274 Description of how alien species might have been introduced to the region and spread between South Africa and elsewhere in Africa Moderate 5, 6 Freshwater fi sh Marr et al. (2017)* 27 Freshwater fi sh species introduced into the water courses of South Africa Moderate 5, 8 Freshwater fi sh SAIAB Few Assessments of speciesspecifi c impacts published in the scientifi c literature, and in theses Low – very few species have been adequately studied 8 Freshwater invertebrates Albany Museum (De Moor, 2015). 3Specimen records held in the National Collection of Freshwater Invertebrates housed in the Albany Museum, Grahamstown, South Africa. 60344 records with approximately 57000 records georeferenced Low, occurrence is based on the genera and not species 5 50 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 TAXON SOURCE (SEE FOOTNOTE*) TOTAL NUMBER OF SPECIES DESCRIPTION LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATOR INFORMED BY THESE DATA Freshwater invertebrates; Terrestrial invertebrates Global Biodiversity Information Facility (www.gbif.org) 1017 Occurrence data of invertebrates Moderate – Data consistently updated on a regular bases 5, 6 Freshwater plants Hill & Coetzee (2017)* 8 A review of the current status of aquatic weeds in South Africa, their socio-economic and environmental impacts and the benefi ts of their control Moderate 5, 6, 8 Fungi; Terrestrial invertebrates Zachariades et al. (2017)*; Klein (2011) 95 Assessment of the status of biological control as a management tool for suppression of invasive alien plants in South Africa; and a published review of biological control agents High 5 Marine invertebrates Iziko SA Museum: Marine invertebrate collection 20 The collection comprises ~130000 lots of specimens (including un-accessioned material). Eleven handwritten catalogues exist for marine invertebrates dating back to 1871 and includes 76184 entries Low – database includes unaccessioned records 5, 6 Marine invertebrates; Marine plants Dr Tammy B. Robinson (C•I•B/SU); Prof. Charles L. Griffi ths (C•I•B/UCT); Ms S. Miza (SANBI) 93 List provided by experts Low – based only on preliminary surveys and many species probably remain undiscovered or unrecognised as alien 5, 6, 8 Microbial species Wood (2017)* 112 Preliminary listing of alien fungal species Very low 5 Reptiles Southern African Reptile Conservation Assessment (SARCA, Navarro 2015) 4 Distribution records for the reptiles of southern Africa, from literature and the SARCA Virtual Museum Low – few records of alien reptiles were included in the assessment 5, 6 Soil biota Janion-Scheepers et al. (2016) 103 Recently published review of soil biota Low 5, 6 Terrestrial and freshwater plants Bews Herbarium (UKZN) 168 Database of well-identifi ed and fairly extensive invasive alien and problem plant collection of the Bews Herbarium, UKZN High – based on published data 5, 6 Terrestrial and freshwater plants Botanical Database of Southern Africa, BODATSA (Ranwashe, 2015) 401 BODATSA is a database that contains the offi cial plant name data records. The data collected covers observational data, species checklists, specimen information, species description, literature and collector information from fi ve herbaria. This is to maintain the most current scientifi cally accurate assessments of southern African plants Moderate – based on regularly updated data 5, 6 51 CHAPTER 4 I THE STATUS OF ALIEN SPECIES TAXON SOURCE (SEE FOOTNOTE*) TOTAL NUMBER OF SPECIES DESCRIPTION LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATOR INFORMED BY THESE DATA Terrestrial and freshwater plants Southern African Plant Invaders Atlas (SAPIA); Henderson & Wilson (2017)*. 773 Atlas maintained by the PPRI-ARC Moderate – based on roadside surveys of varying coverage 5, 6 Terrestrial and freshwater plants (grasses) Visser et al. (2017b)* 256 Review of grasses as invasive alien plants in South Africa. Moderate 5, 8 Terrestrial invertebrates (insects) Albany Museum (Gess, 2015) 72 Database of the terrestrial insect collections of the Albany museum Moderate – based on published data, however has not been updated 6 Terrestrial invertebrates (insects) Dr Ruan Veldtman (SANBI) 9 List provided by expert Low 5 Terrestrial invertebrates (insects) Recently published comprehensive assessment of insect pests on crops and pastures in South Africa (Prinsloo & Uys 2015) 107 Prinsloo & Uys (2015) provided detailed accounts of 693 insect pests of cultivated plants and pastures in South Africa; of these, 107 (14.6%) were alien species Low – the focus of this dataset was on pests of agricultural crops and pastures only. Alien status of species not explicitly included 5 Terrestrial invertebrates (molluscs) David Kesner (SU) 16 Assessments of impacts as part of an ongoing study Moderate 8 Terrestrial invertebrates (molluscs) Prof Dai Herbert (KZN Museum) 39 Database and specimens curated by the KZN Museum Low – records are accurate, but sampling intensity is low 5, 6, 8 Terrestrial plants Clusella-Trullas & Garcia (2017) * 15 Impacts of invasive alien plants on abundance, richness and composition of several taxonomic groups of ectotherms Low 8 Terrestrial plants (cacti) Kaplan et al. (2017)* 31 An assessment of the status of cactus invasions in South Africa. Moderate 5, 6 * Papers were part of the journal special issue that was produced as part of the status report process, see Box 1.3. 52 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 TABLE 4.2 Estimated completeness and accuracy of data required to assign values to alien species indicators in South Africa for diff erent taxonomic groups. The taxonomic groupings are as per the NEM:BA A&IS Regulations. Levels of completeness are: High (information available for > 75% of species); Moderate (information available for 30–75% of species); Low (information available for < 30% of species). Levels of accuracy refer to available data, as follows: High (point distribution data available, or ecology and impacts well-documented); Moderate (quarter-degree grid cell distribution data available or superfi cial studies available on ecology and impacts); Low (no formal mapping or documented studies on ecology and impacts). N/A is not applicable. INDICATOR TAXON COMPLETENESS ACCURACY Number and status of alien species Amphibians High High Birds High High Freshwater fi sh High High Freshwater invertebrates Low Low Mammals High Moderate Marine fi sh N/A N/A Marine invertebrates Low Low Marine plants Low Low Microbes Low Low Reptiles Moderate Moderate Terrestrial and freshwater plants High Moderate Terrestrial invertebrates Low Low Extent of alien species Amphibians High Moderate Birds Moderate Moderate Freshwater fi sh High Low Freshwater invertebrates Low Low Mammals Moderate Moderate Marine fi sh N/A N/A Marine invertebrates Low Low Marine plants Low Low Microbes Low Low Reptiles High Moderate Terrestrial and freshwater plants High Moderate Terrestrial invertebrates Low Low Abundance of alien species Terrestrial and freshwater plants Low Low All other taxa No data No data Impact of alien species Amphibians Moderate Moderate Birds Low Low Freshwater fi sh Low Low Freshwater invertebrates Low Low Mammals Low Low Marine fi sh Low Low Marine invertebrates Low Low Marine plants Low Low Microbes Low Low Reptiles Moderate Moderate Terrestrial and freshwater plants Low Low Terrestrial invertebrates Low Low 53 CHAPTER 4 I THE STATUS OF ALIEN SPECIES 4.2. THE NUMBER AND STATUS OF ALIEN SPECIES IN SOUTH AFRICA The introduction status of alien species can be assessed at diff erent levels, depending on the availability of data (Table 4.3). For many species it was only possible to either determine whether or not it was present in South Africa, while for others it was possible to assess whether the species was absent, introduced but not naturalised, naturalised but not invasive, or invasive. There are very few studies on specifi c groups that provide data at the third and highest level of resolution, i.e. a breakdown of introduction status according to the unifi ed framework of Blackburn et al. (2011), as was done, for example, by Jacobs et al. (2017). Full details of all species are provided in Appendix 3. TABLE 4.3 The relationship between the three levels of resolution that can be used to describe introduction status. Species are placed as far along the introduction-naturalisation-invasion continuum as they can be with the available evidence (e.g. there has to be reported evidence that a species is invasive for it to be classed as such). PRESENCE BASIC INTRODUCTION STATUS STATUS ADAPTED FROM THE UNIFIED FRAMEWORK FOR BIOLOGICAL INVASIONS (BLACKBURN ET AL., 2011) ABSENT Not present A0 (Never introduced beyond limits of indigenous range to the region in question, i.e. South Africa) A1 (Has been introduced beyond limits of indigenous range to South Africa, but no longer present) PRESENT Introduced but not naturalised B1 (in captivity or quarantine) B2 (in cultivation but no measures in place to prevent escape) B3 (released outside of captivity or cultivation) C0 (some escape from captivity or cultivation, but survival limited) C1 (escape and survival outside of captivity or cultivation, but no reproduction) C2 (escape, survival, and reproduction outside of captivity or cultivation, but not clear whether the population is self-sustaining) Naturalised but not invasive C3 (escape, survival, and reproduction outside of captivity or cultivation; population self-sustaining but not spreading) Invasive D1 (escape, survival, reproduction and spread outside of captivity or cultivation; though no evidence of reproduction post-dispersal) D2 (escape, survival, reproduction, spread, and subsequent reproduction outside of captivity or cultivation; though spread as yet limited to a few localities) E (invasive at multiple localities) 4.2.1. Number of alien species in South Africa A total of 2033 alien species were found to be present in South Africa (Table 4.4). All of the species listed as prohibited in the A&IS Regulations were assumed to be absent from South Africa, except for eight prohibited species that are known to have been introduced. These include one bird, one reptile, two amphibians, one microbial species and three invertebrates. 54 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 4.2.2. Status of alien species in South Africa Of the 2033 alien species recorded (or assumed to be present) outside of cultivation or captivity in South Africa, 775 are known to be invasive, 388 are known to be naturalised but not invasive, and 355 are present, but not naturalised. There are a further 516 species where there is insuffi cient information on which to assign them to one of the basic introduction status categories. For terrestrial and freshwater plants, the assessment relied heavily on the SAPIA dataset [see Henderson & Wilson (2017) for a recent analysis of the database]. Unless explicitly stated elsewhere, the assumptions were made that all taxa recorded in SAPIA were naturalised and all taxa in two or more quarter degree grid cells (QDGCs) were invasive. This is not strictly correct, as for a species to be recorded in SAPIA there is no formal assessment of naturalisation, or whether a population is invasive or not, but the assumption will hold for the majority of records. For the other taxa, the determination of a species as invasive was based on expert opinion where available, otherwise the species was not classed as naturalised or invasive (recorded as NA – Not Assessed – in Appendix 3). About one third of the alien species found outside of captivity or cultivation in South Africa are known to have become invasive in South Africa. The proportion diff ered among taxa, with terrestrial, freshwater and marine plants having relatively high proportions (55 – 64%), while reptiles and microbes had no known invasive species (though in the case of microbes this is undoubtedly a classifi cation error). The proportion of all introduced species (for example of a genus or family) that are invasive will be lower than the above estimates, because the estimates express the proportion in terms of species that are already present outside of captivity or cultivation. Reliable estimates of the proportion of species within a genus are only available for some genera of plants, where the proportion of introduced species that becomes invasive ranges from 2% to 22%. At least 36 species in the genus Melaleuca (bottlebrushes) have been introduced to South Africa, and 10 of these have naturalised, including 5 (14%) that are invasive (Jacobs et al. 2017). More than 80 species of the genus Acacia (Australian wattles) have been introduced to South Africa, and 18 (22%) have been recorded as naturalised (Richardson, Le Roux & Wilson 2015). At least 68 species of the genus Pinus (pine trees) have been introduced to South Africa, where eight species have become invasive (12%), and a further 26 species are regarded as potentially invasive (Van Wilgen & Richardson, 2012). Such analyses have the potential to inform risk analyses by identifying high-risk groups (Diez, Hulme & Duncan 2012), but should be moderated by an assessment of whether introduced taxa had an opportunity to become invasive or not (Moodley et al., 2014). Facility for mass-rearing biological control agents – Kim WeaverFacility for mass-rearing biological control agents – Kim Weaver THE SITUATION alien species have established populations outside of cultivation or captivity in South Africa 2033 o f t h e s e a r e i n v a s i v e 775 61 CHAPTER 4 I THE STATUS OF ALIEN SPECIES Parthenium hysterophorus (famine weed): This annual herb is indigenous to tropical America, and has been present in South Africa for over 100 years. It has however only recently begun to spread rapidly, and it now occurs extensively in northern KwaZulu-Natal, Swaziland, and Mpumalanga. The species causes severe allergic reactions in many people who come into contact with it, as well as in livestock and wildlife. It has the potential to substantially reduce rangeland condition. It is placed in category 1(b) (must be controlled). Serious attempts to control this species have only recently begun. Indications are that mechanical control alone will not contain this species, but biological control options are being investigated, and they hold the potential to reduce spread rates and vigour. Photograph: SANBI. Map: L. Henderson Lantana camara (lantana): This shrub was originally introduced into South Africa from south and central America as a garden ornamental. It has extensively invaded the relatively humid parts of South Africa, where it can form dense thickets and transform ecosystems. The species presumably impacts negatively on biodiversity and is also poisonous. It is placed in category 1(b) (must be controlled). Much eff ort has been directed towards biological control of this species, where the level of control has been assessed as substantial. Photograph: SANBI. Map: L. Henderson Micropterus dolomieu (small-mouth bass): This species was imported from north America to provide freshwater angling opportunities. Anglers have introduced the species to several river systems, particularly in the Western and Eastern Cape Provinces. It preys on indigenous fi shes and invertebrates and can change the structure of freshwater species communities. Its regulation is complex. It is placed in category 1(b) (must be controlled) in protected areas, and in category 2 or 3 in dams and rivers where it already occurs. Once established, control is not feasible except in small streams or dams where it may be possible to extirpate populations. Photograph: R. Duane, U.S. Fish and Wildlife Service. Map: SAIAB. 62 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 Acridotheres tristis (common mynah): This species was brought to Durban from Asia in 1888, from where it has spread to most of northeast South Africa. It favours urban environments (where populations can reach hundreds of thousands), but probably has negligible impacts on natural and rural habitats. It is listed as category 3 (does not require control, but may not be moved or traded). Large-scale control would probably be impossible, but occasional removal of isolated individuals has been carried out, for example in Cape Town and the Kruger National Park. Photograph: R. Taylor. Map: ADU. Mytilus galloprovincialis (Mediterranean mussel): This species was accidentally introduced from Europe to South Africa’s west coast in about 1979, almost certainly by shipping. It spread rapidly to Namibia, and more slowly to the Eastern Cape. It now dominates most of the rocky shores of the west and south coasts, where it forms dense, multi-layered beds that monopolise space on intertidal rocks. It can be benefi cial as a food source to both humans and animals (for example the African oystercatcher, Haematopus ostralegus). Listed as category 2 (cultivation and trade allowed with a permit). Its control would probably be impossible, given the wide range, prolifi c reproductive habits, and widely-dispersing larvae. Photograph: S. Miza. Map drawn from data supplied by Dr T. Robinson. 4.4. ABUNDANCE OF ALIEN SPECIES Two sources of data were available to estimate the Abundance of alien species, both relating to plants. The fi rst is contained in the 1998 report of the Water Research Commission (Appendix 5 in Versfeld, Le Maitre & Chapman 1998). These estimates are very crude and 20 years out of date, so the level of confi dence in these estimates is very low. There are no comparable data for any other high-level taxa. The second is the National Alien Invasive Plant Survey of the Agricultural Research Council (Kotzé et al., 2010). This survey has a focus of those species targeted for control by the Working for Water programme (mainly trees and shrubs), and it excludes a very large proportion of arid South Africa. In addition, the methodology on which this survey is based has never been adequately documented, and therefore there can only be a low degree of confi dence in the estimates at this stage. In addition, because of diff erences in methodology and sampling coverage, the fi ndings of Versfeld, Le Maitre & Chapman (1998) and the National Alien Invasive Plant Survey are not comparable (Table 4.5). 63 CHAPTER 4 I THE STATUS OF ALIEN SPECIES TABLE 4.5 Invasive plant taxa listed as the most abundant in South Africa in terms of cover by Versfeld, Le Maitre & Chapman (1998), and by Kotzé et al. (2010). Species were ranked by condensed invaded area (mean % cover × area occupied). Condensed ha is the equivalent area occupied at a canopy cover of 100% (i.e. 50% cover on 10 ha = 5 condensed ha). Note that estimates from Kotzé et al. (2010) exclude almost all of the arid parts of South Africa. TAXON EXTENT ABUNDANCE ABUNDANCE (total invaded area in 1000s of ha as estimated by Versfeld, Le Maitre & Chapman 1998) (condensed invaded area in 1000s of ha as estimated by Versfeld, Le Maitre & Chapman 1998) (condensed invaded area in 1000s of ha as estimated by Kotzé et al., 2010) Acacia cyclops (rooikrans) 1900 339 55 Prosopis species (mesquite) 1800 173 Not estimated Acacia mearnsii (black wattle) 2500 131 474 Acacia saligna (Port Jackson) 1900 108 50 Solanum mauritianum (bugweed) 1800 89 40 Pinus species (pine trees) 3000 77 133 Opuntia species (cacti) 1800 75 95 Melia azedarach (syringa tree) 3000 73 Not estimated Lantana camara (lantana) 2200 69 32 Hakea species (hakea) 700 64 36 Eucalyptus species (gum trees) 2429 63 274 Chromolaena odorata (triffi d weed) 534 43 102 Populus species (poplar trees) 1305 15 58 Salix babylonica (weeping willow) 121 12 38 4.5. THE IMPACT OF ALIEN SPECIES The impact of alien species in South Africa has, as in other countries, rarely been investigated, and where it has been done, the estimates are often in units that are not directly comparable. To alleviate the problem of comparing diff erent types of impact measured in diff erent ways, the Environmental Impact Classifi cation for Alien Taxa (EICAT) Scheme (Blackburn et al., 2014) has recently been adopted by the IUCN. A Socio-Economic Classifi cation of Alien Taxa scheme (SECIAT, Bacher et al., 2018) has also recently been developed. However, at the time of writing this report, these schemes had not yet been implemented in South Africa. The impact of some species has been formally assessed at a global scale (for example Evans, Kumschick & Blackburn 2016 for birds and Kumschick et al., 2017 for amphibians). These assessments are not used here, as the specifi c impacts in South Africa would need to be assessed for a national-scale status report. Therefore, for indicator 8 - Impact of alien species, all species presently fall into the category of “not assessed”. Conducting South African specifi c EICAT and SEICAT assessments is a priority for future reports (Chapter 8). There was, however, a recent exercise in which experts were asked for their opinion on the impact of listed species (Zengeya et al., 2017). In this study, the 552 species listed in the NEM:BA A&IS Regulations were scored by taxon-specifi c experts according to their ecological and their socio-economic impacts (separately for negative 64 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 and positive impacts), on a scale from 1 to 10 using wording similar to the EICAT scheme. For the purposes of discussion, the scores in Zengeya et al. (2017) were grouped into fi ve categories that correspond in spirit to the fi ve categories of the EICAT and SEICAT schemes [1–2 is negligible impact ~ Minimal Concern (MC) under EICAT; 3–4 are a few impacts ~ Minor (MI); 5–6 is some impact ~ Moderate (MO); 7–8 are major impacts ~ Major (MR); and 9–10 are severe impacts ~ Massive (MV)], with each taxon assigned to a category according to the maximum impact scored (i.e. the higher of either the environmental or socio-economic impacts). Using the scheme of Zengeya et al. (2017), 25 species were assessed as having a severe impact, and 82 as having a major impact (Table 4.6). Of these 107 species, most (80) are terrestrial or freshwater plants, eight are mammals, fi ve each are freshwater fi sh, freshwater invertebrates and terrestrial invertebrates, two are amphibians, and there is one bird and one marine plant species. The greatest impacts associated with invasive species in terrestrial habitats are due to invading plants (Table 4.7). Depending on the species, they can reduce rangeland condition and carrying capacity, reduce surface water runoff and groundwater recharge, increase fi re hazards, and erode biodiversity. When introduced to off shore islands, they can imperil island fauna and fl ora (Box 5.3). In a review of the state of knowledge regarding the impacts of invasive plants in South Africa, Richardson & Van Wilgen (2004) concluded that, with the notable exception of the impacts of woody plants on water resources, very little was documented. Although there have subsequently been additional studies, the impacts of the vast majority of invasive species remains unstudied. One notable exception is provided by invasive trees in the genus Prosopis (mesquite trees), where at least ten separate studies have documented impacts on indigenous invertebrates, birds, mammals, trees and grasses, rangeland condition, groundwater recharge and human health in both biophysical and economic terms (Box 4.2). In some cases, indigenous knowledge systems provide valuable insights into impact. For example, Shackleton et al. (2017b) used semi-structured questionnaires to assess local perceptions associated with invasive cacti in Laikipia County, Kenya. This study was useful in identifying and ranking the main impacts associated with the species concerned, and this approach could be used more often in future to expand knowledge. Finally, some species can have both positive and negative impacts (Box 4.3), and these cases present special challenges when it comes to fi nding acceptable and sustainable approaches to their management. In freshwater ecosystems, invasive fi sh and crustaceans, as well as the diseases they carry, can have large impacts on indigenous freshwater biota. Again, well-documented cases are rare, but a small number of robust studies exist. For example, Shelton, Samways & Day (2014) documented the impacts of Oncorhynchus mykiss (rainbow trout) in the rivers and streams of the Cape Floristic Region (CFR). They found mean densities of indigenous Pseudobarbus burchelli (Breede River redfi n), Sandelia capensis (Cape kurper) and Galaxias zebratus (Cape galaxias), were 89–97% lower in invaded streams than in streams without trout. Furthermore, while indigenous fi sh were present at 100% of all sites without trout, they were not recorded at all at 58% of the invaded sites. The study concluded that alien trout have depleted the abundance of CFR-endemic fi shes through size-selective predation. Of the 93 alien marine species recorded, impact was assessed for only 12 species. As such, according to the scheme used here, 81 species are data defi cient, 2 have few impacts, 7 have negligible impacts, 5 have some impacts and 2 have major impacts (T. Robinson & C. Griffi ths unpublished data). Five species have economic or human health impacts, but these have not been formally assessed. Mytilus galloprovincialis (Mediterranean mussel) is believed to have the greatest impacts in South African marine environments. First recorded in the late 1970s, this species presently occupies more than 2000 km of coastline, occurring along the whole of the West Coast and as far east as East London (Robinson et al., 2005). Within its range, this mussel impacts on a variety of indigenous species and 65 CHAPTER 4 I THE STATUS OF ALIEN SPECIES ultimately has altered the structure of rocky shore communities. Along the West Coast M.galloprovincialis dominates primary rock surfaces at the expense of various competitively inferior indigenous mussel and limpet species (Branch & Steff ani, 2004; Robinson et al., 2007), while along the South Coast it co-exists with the indigenous mussel Perna perna (Linnaeus) (Bownes & McQuaid 2006). Interestingly, this mussel has also increased the diversity and abundance of indigenous fauna on invaded shores, as it forms complex mussel beds that increase habitat availability for indigenous biota (Robinson et al., 2007, Sadchatheeswaran, Branch & Robinson 2015). This change in habitat structure has signifi cantly altered rocky shore communities. The fi ve species that have some impacts are Sagartia ornata (brooding sea anemone), Ficopomatus enigmaticus (estuarine tube-worm), Balanus glandula (Pacifi c barnacle), Semimytilus algosus (pacifi c mussel) and Ciona intestinalis (sea vase). These invasions have resulted in population-level changes in indigenous species. The most recently arrived species, S. algosus is particularly concerning. This mussel was fi rst detected along the West Coast in 2009 (De Greef, Griffi ths & Zeeman 2013) but has recently crossed the biogeographic barrier of Cape Point and now occurs in False Bay (T. Robinson unpublished data). Laboratory studies have suggested that this mussel could survive along the South Coast (Alexander et al., 2015) and this raises concerns that the full extent of the impacts of this alien are yet to be realised. TABLE 4.6 The number of species known to occur in South Africa, assigned to various categories of impact status based on expert opinion of the impact in South Africa. The impact of biological control agents is positive, so they were not assigned to an impact status hence they were represented as NE (not evaluated). See text for defi nitions of impact status. TAXON IMPACT DATA DEFICIENT NEGLIGIBLE FEW SOME MAJOR SEVERE NOT EVALUATED TOTALS Amphibians 15 1 2 1 2 0 0 21 Birds 0 5 5 8 1 0 73 92 Freshwater fi sh 1 0 5 9 4 1 6 26 Freshwater invertebrates 0 7 9 4 1 4 4 29 Mammals 0 4 16 11 8 0 3 42 Marine invertebrates 73 2 1 4 1 0 4 85 Marine plants 8 0 0 0 0 0 0 8 Microbial species 0 6 0 1 0 0 103 110 Reptiles 18 11 11 8 0 0 80 128 Terrestrial and freshwater plants 2 48 116 133 63 17 514 893 Terrestrial invertebrates 5 94 16 20 2 3 460 600 Totals 122 178 181 199 82 25 1247 2034 Twenty-fi ve species were considered to have a severe impact (Table 4.7). Most of these (17 species) were plants, which included seven species of Australian trees and shrubs in the genus Acacia. The list also included some examples of severe impact by species in other high-level taxa, including one freshwater fi sh species, one amphibian species, three terrestrial mollusc species, and one terrestrial insect species. 66 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 TABLE 4.7 Invasive species assessed based on expert opinion to have severe impacts in South Africa. The regulatory category “context specifi c” applies to species that have been placed into various categories depending on their location. TAXON SPECIES REGULATORY CATEGORY EXTENT (QDGCs occupied) EXAMPLES OF IMPACTS TERRESTRIAL AND FRESHWATER PLANTS Acacia cyclops (rooikrans) 1b 115 Forms closed-canopy stands, excluding most other species; disrupts natural sand movement in coastal ecosystems; increases fi re intensity, leading to soil damage and erosion Acacia dealbata (silver wattle) 2 240 Forms closed-canopy stands, excluding most other species, especially in riparian areas; uses excessive amounts of water Acacia decurrens and hybrids (green wattle) 2 105 Forms closed-canopy stands, excluding most other species, especially in riparian areas; uses excessive amounts of water Acacia longifolia (long leaved wattle) 1b 53 Forms closed-canopy stands, excluding most other species; uses excessive amounts of water Acacia mearnsii and hybrids (black wattle) 2 369 Forms closed-canopy stands, excluding most other species, especially in riparian areas; uses excessive amounts of water Acacia melanoxylon (Australian blackwood) 2 124 Widespread invader in forests and forest ecotones. Excludes other species Acacia saligna (Port Jackson) 1b 126 Forms closed-canopy stands, excluding most other species Agrostis stolonifera (creeping bent grass) Context specifi c Off shore islands Forms extensive clonal patches by means of long stolons, impacting on indigenous plant species on off shore islands Chromolaena odorata (triffi d weed) 1b 110 Can dominate in grassland and savanna ecosystems, especially in disturbed areas, and reduces biodiversity and rangeland productivity Dolichandra unguis-cati (cat’s claw creeper) 1b 44 A climbing vine that invades forests, woodlands and forest margins, smothering and collapsing trees Echium plantagineum (Patterson’s curse) 1b 104 An invader of pastures and cultivated lands Eucalyptus camaldulensis (river red gum) Context specifi c 136 Forms closed-canopy stands in riparian areas, excluding most other species; uses excessive amounts of water Hakea sericea (silky hakea) 1b 39 Forms closed-canopy stands in fynbos mountain catchments, and displaces most other species. Increases fi re intensity, leading to soil damage and excessive erosion Lantana camara (lantana) 1b 312 Widespread invasive shrub that can dominate in savanna and grassland regions, and reduces biodiversity and rangeland productivity Prosopis glandulosa var. torreyana (honey mesquite) Context specifi c 112 Many well-documented impacts on biodiversity, groundwater supplies, rangeland productivity and human livelihoods and health (see Box 4.2) Prosopis velutina (velvet mesquite) Context specifi c 5Many well-documented impacts on biodiversity, groundwater supplies, rangeland productivity and human livelihoods TERRESTRIAL INVERTEBRATES Cornu aspersum (common garden snail) Unlisted 115 Pestiferous, documented for damage to commercial and ornamental crops, as well as domestic gardens Deroceras invadens (tramp slug) Unlisted 10 Pest of garden vegetables Linepithema humile (Argentine ant) 1b 36 Disrupts seed dispersal mechanisms in fynbos, potentially leading to collapse of plant reproduction systems FRESHWATER INVERTEBRATES Cherax quadricarinatus (redclaw crayfi sh) 1b 3 Negatively impacts indigenous freshwater species. It also carries parasites which could have further impacts on indigenous species Schyzocotyle acheilognathi (Asian tapeworm) Unlisted 5 A parasite introduced on alien fi sh that attacks indigenous fi sh species Pseudodactlogyrus anguillae (gill fl ukes) Unlisted 2 A parasite introduced on alien fi sh that attacks indigenous fi sh species Procambarus clarkii (red swamp crayfi sh) Prohibited 4 Physical damage to aquatic habitats; disrupts nutrient cycling; preys on indigenous species FRESHWATER FISH Micropterus dolomieu (smallmouth bass) Context specifi c 60 Predatory fi sh that negatively impacts indigenous fi sh and freshwater invertebrates 67 CHAPTER 4 I THE STATUS OF ALIEN SPECIES BOX 4.2 PROSOPIS TREES IN SOUTH AFRICA: AN INVASIVE SPECIES WHOSE IMPACTS HAVE BEEN WELL DOCUMENTED. Trees in the genus Prosopis (mesquite; Fabaceae) include several species and their hybrids that are among the world’s most damaging invasive plants. Mesquite trees were introduced to South Africa to provide fodder and shade for livestock, but as elsewhere in the world they have become invasive, generating negative impacts. Prosopis is one of the few invasive alien taxa whose ecological and economic impacts have been well studied and documented. Thicket of Prosopis – Arne Witt Ten individual studies were conducted in Africa between 1996 and 2016, in which impacts of Prosopis were quantifi ed. This knowledge was used to underpin an economic assessment of the net worth of the genus. The individual aspects studied, and the fi ndings, are summarised here. Dung beetle diversity: Invasion reduced the number of dung beetle species from 41 to 34, and reduced their density markedly. Large species, and rare species, showed the biggest declines. Bird diversity: Bird communities in invaded sites were found to be less species-rich and less diverse; raptors were eliminated, frugivores became sparse and the number of insectivore species was halved in invaded sites. Other bird feeding guilds (nectarivores, seedeaters) were less aff ected. Indigenous zebra species: In Ethiopia, invasion signifi cantly reduced the cover of perennial grasses from 68% to 2%, increased soil surface exposure from 30% to 80%, and lowered the number of grass species from seven to two. This has particularly negative implications for the survival of an isolated population of the endangered Grevy’s zebra (Equus grevyi). Grazing capacity: Invasion by Prosopis with only 15% cover reduced grazing capacity by 34%, but clearing improved grazing capacity by 110% within 6 years. Density and species richness of indigenous plants: Invasion reduced the density, richness and diversity of indigenous plants. For example, indigenous trees declined from eight to three species when invasions doubled in density, and the cover of indigenous perennial grasses and herbaceous plants declined from 15–20% to zero. Inter-specifi c competition with indigenous trees: Invasive Prosopis and indigenous Acacia erioloba were found to compete for groundwater, increasing the likelihood of mortality in A. erioloba in times of stress. Groundwater levels: Invasions by deep-rooted Prosopis trees reduced groundwater levels. Economic consequences of invasion: The value of benefi ts of Prosopis was found to marginally exceed the cost of impacts, but this was predicted to change within a few years as Prosopis continues to spread, resulting in net negative impacts that will grow over time. Health consequences: A study in Mali, West Africa, demonstrated that villages with Prosopis invasions supported three times more Anopheles mosquitoes, thus increasing the risk of contracting malaria. Key references: Muller et al. (2017); Shackleton et al. (2014); Wise, Van Wilgen & Le Maitre (2012). 68 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 BOX 4.3 EXAMPLES OF CONFLICT SPECIES THAT CAN BE SIMULTANEOUSLY BENEFICIAL AND HARMFUL Alien species can simultaneously bring many benefi ts and cause substantial environmental harm, very often leading to confl icts over their management. The impacts grow over time as invasions spread, and as societal perceptions of the value of alien species change as understanding grows and as values shift. The management of these “confl ict” species is particularly challenging, and requires trade-off s if benefi ts are to be maximised and harm minimised. Some of the prominent confl ict species in South Africa are described here. Pine trees (Pinus species) were planted extensively in South Africa after the 1930s to provide timber. Planted pines have invaded the adjacent fynbos in the Cape Floristic Region. Invasion by alien pine trees was recognized as a problem as early as the 1940s, and coordinated attempts to clear these invasions began in the 1970s, but despite this, invasions are growing. Both the need to prevent water and biodiversity loss and to stimulate economic growth are becoming more acute, leading to polarized views regarding the advantages and disadvantages of pines. To date, suitable compromises have not been found, nor do they seem possible. Photographer: B. van Wilgen Rainbow trout (Oncorhynchus mykiss) were deliberately introduced to South Africa to create self-sustaining populations outside of captivity or cultivation. Trout introductions support recreational and commercial fi sheries that contribute to the economy. These intentional Photographer: Cape Nature introductions continue to occur despite changing views on the stocking of non-indigenous species due to their demonstrated ecological impacts. A major problem with managing invasive trout is that once established, control is extremely diffi cult. Implementing management interventions is also complicated by the economic contributions of angling and aquaculture, and by resistance from anglers who actively support continued stocking. Attempts by government to add trout to the list of regulated species have failed to date, and a management impasse continues. Mallards (Anas platyrhynchos), have been widely introduced into South Africa, where feral mallards interbreed with the indigenous Yellow-billed Duck (Anas undulata). Attempts to remove mallards by the City of Cape Town were eff ectively halted because the arguments for the campaign (genetic contamination of a single indigenous species) were less convincing to the public than Photographer: S. Turner arguments for the widespread ecological impacts of more damaging invasive species. 69 CHAPTER 4 I THE STATUS OF ALIEN SPECIES 4.6. SYNTHESIS AND INDICATOR VALUES The analysis of the number of alien species and their introduction status in South Africa is based on the 2034 species listed in Appendix 3. Because introduction status is not recorded explicitly in databases, it was necessary to make several assumptions, and these need to be tested in future reports. For many taxa, it was not possible to assign species to a category of introduction status due to a lack of information. However it is clear that South Africa has a major invasion debt. Well over 100 new alien plant taxa have been recorded as escaped from cultivation in the past decade, and the recorded range of almost all invasive plants has increased signifi cantly (Henderson & Wilson 2017). This is a major cause for concern, as it clearly indicates that the problems associated with alien species are set to increase. Estimates of species extent were limited to 835 taxa for which reliable distribution data were available. Levels of confi dence in these estimates are moderate for terrestrial and freshwater plants and for birds, but low for other taxa. This can form the basis for tracking changes in range over time. There are no recent reliable estimates of alien species abundance. For alien plants, there are estimates made by Le Maitre, Versfeld & Chapman (2000), but these are crude and more than 20 years out of date. Estimates made by Kotzé et al. (2010) do not cover the whole country, are restricted to certain taxa, group some species by genus or family, and there is uncertainty regarding the methodology employed. It is therefore not possible at this stage to provide estimates of individual species abundance. Finally, the issue of quantifying the impacts of alien species remains a challenge. For the vast majority of species, no studies document impacts, and there have been almost no formal assessments of impact using either the EICAT or SEICAT schemes at the scale of South Africa. This assessment therefore had to rely on expert opinion to assign species to categories of impact. This, however, is not suitable for presenting as an indicator, as the methodology is not repeatable. Formal assessments are required for the next report if trends in impact are to be tracked. In the meantime, this report does not assign values to impact indicators in Table 4.8, although the estimate based on expert opinion is presented in the high-level indicators in Table 6.9. Cacti are among the most dominant invasive plant groups in South Africa, where they impact negatively on biodiversity, ecological functioning and agricultural productivity. Cacti are also important ornamental plants, and around 300 species of cacti are imported to South Africa annually, and the trade in these plants contributes to the economy. A management framework has been developed in which four strategic objectives were proposed: Photographer: SANBI (1) all invasive and potentially invasive cactus species should be prevented from entering the country, (2) new incursions of cactus species must be rapidly detected and eradicated, (3) the impacts of invasive cacti must be reduced and contained, and (4) useful cacti (both invasive and non-invasive species) must be utilised sustainably to minimise the risk of further negative impacts. 70 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 TABLE 4.8 Indicators used for reporting on the status of alien species. For full details of how to calculate the indicators, see Appendix 1. INDICATOR METRIC BASIC ADVANCED LEVEL OF CONFIDENCE NOTES 5. Number and status of alien species 5.1. Number of invasive species: 775 5.2. Number of alien species in categories Alien but not naturalised: 355 Naturalised but not invasive: 388 Invasive: 775 Not assessed: 516 Number of species in each of 12 stages No data Low Status not explicitly or consistently recorded in databases, so assumptions were used. These numbers focus on alien species outside of captivity or cultivation (this was not captured consistently). A census of all aliens is needed 6. Extent of alien species 6.1. Extent of species per province (based on 835 species of known extent). (see Figure 4.1) 6.2. At a quarterdegree grid cell scale, many species have a limited distribution, with some being relatively widespread (see Figure 4.1; and Figure 4.3). 6.3. Range size for each species No data Moderate for terrestrial and freshwater plants and birds; low for all other taxa Plants and birds are conspicuous and the relevant atlases are regularly updated 7. Abundance of alien species 7.1. Categorical measure of abundance No data 7.2. Number of individuals or area occupied No data 7.3. Abundance estimates by stages or age cohorts. No data N/A There are only abundance data for alien plants, but these are crude and 20 years out of date 8. Impact of alien species 8.1. Number of species in impact categories No data 8.2. Detailed impacts per species for a range of impact mechanisms No data N/A Species have been placed into impact categories based on expert opinion, and these are presented in the text , but no species have been formally assessed according to EICAT or SEICAT guidelines B. Number of species with major impacts 107 species Not applicable Based entirely on expert opinion, and so does not represent an appropriate base-line 77 CHAPTER 5 I THE STATUS OF INVADED AREAS 5.2.3. Alien species richness at diff erent stages of the Unifi ed Framework for Biological Invasions If the size of the future problems on biological invasions is to be estimated, then spatial data on the number of species at diff erent stages along the introduction-naturalisation-invasion continuum would be required (i.e. area-based invasion debt). However, the introduction status of all alien species is not known for any groups. 5.3. RELATIVE ALIEN SPECIES RICHNESS Estimates of Relative alien species richness at provincial scales could only be made for invasive taxa for which reliable distribution data were available (plants and birds). Relative invasive bird species richness per province ranged from 1.0% in Limpopo to 1.6% in the Free State. Relative invasive plant species richness per province ranged from 7% in the Northern Cape to 25% in the Northwest. Note that the number of indigenous plant species is based on BODATSA, which has incomplete records. This indicator will be of value to management when used in concert with Alien species richness and Relative invasive abundance at an appropriate scale, e.g. per protected area, or management zone, and as tracked over time. However, these data are not available at present. 5.4. RELATIVE INVASIVE ABUNDANCE There are no reliable estimates of invasive plant species cover or biomass per province (Box 5.1). Crude estimates made by Versfeld, Le Maitre & Chapman (1998) confi rmed what is generally accepted, namely that the Western Cape is the most invaded province, followed by Mpumalanga, Northern Cape and KwaZulu-Natal. Approximately 28% of the area of the Western Cape was invaded by alien plants at a range of cover classes, with the most important taxa being wattles (genus Acacia), pines (genus Pinus) and hakeas (genus Hakea). Approximately 16% of the area of the Mpumalanga was invaded by alien plants at a range of cover classes, with the most important taxa being wattles (genus Acacia), Lantana camara (lantana) and Solanum mauritianum (bugweed). Invasions in the Northern Cape Province were dominated by mesquite trees (genus Prosopis), which accounted for almost all of the invasions that covered 14% of the province at the time. In KwaZulu-Natal, where invasions covered 9% of the province, the most important contributing taxa were wattles (genus Acacia), Chromolaena odorata (triffi d weed), cacti (in particular the genus Opuntia) and Solanum mauritianum (bugweed). Other provinces were all estimated to have less than 3% cover by invasive alien plants (with the admission that the Eastern Cape Province was substantially under-sampled by Versfeld, Le Maitre & Chapman (1998). These estimates, besides being crude, are more than 20 years out of date, and both the extent of invasions and the relative dominance of species, have changed considerably since then (Henderson & Wilson, 2017). A more recent estimate by Kotzé et al. (2010) confi rmed Acacia mearnsii (black wattle) as the most abundant invasive alien plant species, followed by gum trees (Eucalyptus species), pine trees (Pinus species) and Chromolaena odorata (triffi d weed, see Table 4.5). However, the study by Kotzé et al. (2010) only targeted alien plant species of interest to the Working for Water programme (mainly trees and shrubs), excluded a very large proportion of arid South Africa, and is based on methodology that has not been adequately documented. As a result, there can only be a low degree of confi dence in the estimates at this stage. 78 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 5.5. IMPACT OF INVASIONS While the impacts of individual invasive species have been quantifi ed in a number of cases, i.e. Alien species impact, such studies are rare (Box 4.2). Fewer studies have attempted to quantify the combined impacts of cooccurring invasive species on a particular area, i.e. Impact of invasions. In South Africa, some work has been done to quantify the impacts of invasive plants on selected ecosystem services or ecosystem intactness, either at a biome scale (for water resources, livestock production from natural rangelands, and for biodiversity intactness, Van Wilgen et al., 2008), or at a catchment scale for water resources (Le Maitre et al., 2000; 2016). The fi ndings of these studies are summarised below. 5.5.1. Impacts on surface water runoff and groundwater by primary catchment The adverse impacts of alien plant invasions on water fl ows have provided a strong argument for the control of invasive plants (Le Maitre et al., 1996; Van Wilgen, Cowling & Burgers 1996). Le Maitre, Versfeld & Chapman (2000) estimated that the total reduction in runoff due to invading alien plants was about 3 300 million m3 per year, or about 7% of the country’s mean annual runoff . About a third of this estimated water use, by volume, was accounted for by invasive plants in the Western Cape, followed by KwaZulu-Natal (17%), the Eastern Cape (17%) and Mpumalanga (14%). This section summarises current estimates of the impacts on water fl ows for primary catchments and biomes and highlights the species with the greatest impacts. The reductions take the form of changes in runoff from invaded dryland areas due to increased evaporation, and evaporation of groundwater from invaded river fl oodplains (riparian invasions) and from invaded areas with groundwater in aquifers accessible to root systems (groundwater). The total reduction is expressed as a proportion of mean annual runoff because all these reductions ultimately result in a reduction in surface water runoff as measured in rivers. Le Maitre et al. (2016) subsequently used new information on the distribution of invasive alien plants, and improved fl ow reduction models, to put forward a revised estimate of 1 444 million m3 per year, or 2.9% of the naturalised mean annual runoff (less than half of the 3 300 million m3 per year estimated in 2000). Two main factors accounted for the diff erence between the estimates of Le Maitre, Versfeld & Chapman (2000) and those of Le Maitre et al. (2016). The fi rst was a decrease in the estimated unit-area fl ow reduction to 970 m3 per ha per year compared with 1 900 m3 per ha per year estimated in 1998, largely due to refi nements of the models. The second was the use of a smaller estimated invaded area (alien plants that covered 1 million ha compared to the 1.76 million ha used in the 2000 assessment). This was due to the use of a new alien plant distribution data set (Kotzé et al., 2010) that excluded South Africa’s arid interior and thus the entire Nama Karoo, almost all of the Succulent Karoo and Desert biomes, about a third of the Savanna, and half of the Grassland biome. This meant that the 2016 fi gure for water use by invasive plants was an under-estimate. In addition, the revised estimate was also considered to be an underestimate by Le Maitre et al. (2016) because the extent and impacts of riparian invasions had been underestimated. The estimate of Le Maitre et al. (2016) of 1 444 million m3 per year was based on the mapped data showing that only 4–6% of invasions of some of the major contributing taxa (Acacia mearnsii, black wattle, Eucalyptus, gum trees, Populus, poplar trees, and Salix, willows) were found in riparian zones (where water use is higher). However, the actual proportion of these taxa in riparian zones is probably much higher, and this could increase the estimate by as much as 70%, from 1444 to 2444 million m3 per year. 79 CHAPTER 5 I THE STATUS OF INVADED AREAS Impacts on surface water runoff by primary catchment: The largest reductions (over 5% of mean annual runoff ) were in the Western Cape (catchments G, H and K), the Eastern Cape (catchments K, M and R), and KwaZulu-Natal (catchment U) (Table 5.3). Only about 5% of the Orange River system (catchment D) was mapped, as was only about 33% of the Vaal River system, so the total reductions in these catchments were signifi cantly underestimated. The main diff erence from the 2000 estimate is the much greater estimated reductions in catchments in the Eastern Cape (where alien plant invasions were inadequately accounted for in the 2000 estimate). TABLE 5.3 The estimated extent of reductions in surface water runoff due to invasive alien plants in South Africa’s primary catchments. Table adapted from Le Maitre et al. (2016). Condensed ha is the equivalent area occupied at a canopy cover of 100% (i.e. 50% cover on 10 ha = 5 condensed ha). See Figure 5.3 for the location of primary catchments. PRIMARY CATCHMENT RIVER SYSTEMS ESTIMATED INVASION LEVEL (CONDENSED HA) ESTIMATED REDUCTION (MILLIONS OF m3) ESTIMATED REDUCTION (% OF MEAN ANNUAL RUNOFF) A Crocodile-Limpopo 86510 24.44 1.06 B Olifants-Letaba 123328 61.79 2.13 C Vaal 138557 64.25 1.53 D Orange 54383 31.57 0.46 E Olifants-Doring 4825 3.65 0.31 F Namaqualand coast 795 0.00 0.02 G Berg-Agulhas 92970 111.36 6.04 H Breede-Goukou 45164 126.21 6.11 J Gouritz 25438 11.69 1.86 K Hartenbos-Kromme 60951 102.51 8.43 L Gamtoos 24228 10.86 2.09 M Swartkops 23662 11.64 6.46 N Sundays 39906 0.89 0.34 P Bushmans 12432 3.31 1.99 Q Great Fish 30385 4.83 0.90 R Keiskamma-Nahoon 45414 42.92 7.41 S Great Kei 59130 46.58 4.49 T Umbashe-Umzimvubu 220942 321.96 4.51 U uMzimkulu-uMvoti 111698 154.35 5.03 V Thukela 81139 100.87 2.60 W uMfolozi-Pongola 154984 148.66 2.31 X Incomati 58025 59.19 1.90 Total 1494867 1443.56 2.88 80 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 FIGURE 5.3 Estimates of the reductions in mean annual runoff (MAR) due to invasive alien plants in the quaternary catchments of South Africa. Capital letters refer to primary catchments. The quaternary catchments that were completely excluded are shown in grey; many others were only partially mapped; the Kruger National Park was also excluded. Map: DLeMaitre unpublished data. Impacts on surface water runoff by biome: Although some biomes were excluded or only partially mapped by Kotzé et al. (2010), the data show that while the Grassland Biome and the wetter areas of the Savanna Biome (i.e. excluding the Kalahari) have the most extensive invasions, the most heavily invaded ones are the Indian Ocean Coastal Belt and Fynbos. The invasions and impacts for the Forest biome (Table 5.4) are overestimated, due to mapping scale mismatches. This means that the greatest percentage reductions are found in the Indian Ocean Coastal Belt and in the Fynbos biome. However, the volume of the reduction for the Grassland is of particular concern because the surface runoff from this biome is critical for water supplies to Gauteng, the EThikweni Region and Mangaung, as well as for power generation and much of the irrigated agriculture in South Africa. 81 CHAPTER 5 I THE STATUS OF INVADED AREAS TABLE 5.4 The estimated impacts on the annual surface water runoff of all invasions in the biomes included in the landscape mapping for the RSA by Kotzé et al. (2010). MAR = mean annual runoff . STATISTIC BIOME ALBANY THICKET FOREST FYNBOS GRASSLAND INDIAN OCEAN COASTAL BELT SAVANNA (wetter areas only) Total reduction (million m3/yr) 23 12 365 621 113 309 MAR (million m3/yr) 659 66 5213 16709 1509 7726 Reduction (% MAR) 3.48 18.36 6.99 3.72 7.52 4.00 The available estimates of the impact of invasive plants on surface water runoff from catchments therefore are underestimates and, at best, coarse approximations, due to the issues regarding the accuracy of the mapping and the number of assumptions and extrapolations that had to be made. Further research is needed to provide better estimates of the impacts. In the 2016 estimate, the taxon with the greatest estimated impact was wattles (Acacia mearnsii, black wattle, A.dealbata, silver wattle, and A. decurrens, green wattle) which accounted for 34% of the reductions, followed by Pinus species (pine trees) (19.3%) and Eucalyptus species (gum trees) (15.8%) (Table 5.5). Nearly 70% of the wattle invasions, 60% of gum trees, 40% of pines and most of the poplar and willow invasions are in the Grassland biome and explain why estimated reductions in this biome are so hig. Prosopis (mesquite) invasions in the Northern Cape were mapped in 2007 (Van den Berg 2010) and this information was used to estimate a reduction of about 9 million m3/yr, most of this being in the Orange River catchment (Le Maitre et al., 2013). TABLE 5.5 A comparison of the estimated extent and impact of invasions by diff erent taxa on the mean annual surface water runoff in South Africa (Middleton & Bailey 2008) based on the landscape mapping for the RSA by Kotzé et al. (2010). Condensed ha is the equivalent area at a canopy cover of 100% (i.e. 50% cover on 10 ha = 5 condensed ha) ESTIMATED CONDENSED AREA (HA) ESTIMATED REDUCTION (MILLION M3) ESTIMATED REDUCTION (MM RAINFALL EQUIVALENT) Acacia cyclops (rooikrans) 54679 28.95 53 Acacia mearnsii (black wattle) 474489 483.23 102 Acacia melanoxylon (Australian blackwood) 2796 18.07 646 Acacia saligna (Port Jackson willow) 50052 11.66 23 Agave spp. (Century plants) 11341 0.89 8 Arundo donax (giant reed) 3202 1.59 50 Atriplex nummularia (old man saltbush) 5862 0.94 16 Caesalpinia decapetala (Mauritius thorn) 8830 10.95 124 82 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 ESTIMATED CONDENSED AREA (HA) ESTIMATED REDUCTION (MILLION M3) ESTIMATED REDUCTION (MM RAINFALL EQUIVALENT) Cereus jamacaru (queen of the night) 10948 0.13 1 Cestrum spp. (cestrums) 7217 19.27 267 Chromolaena odorata (triffi d weed) 101992 100.29 98 Eucalyptus spp. (gum trees) 273573 217.37 79 Hakea spp. (hakeas) 36344 72.20 199 Jacaranda mimosifolia (jacaranda) 4200 1.76 42 Lantana camara (lantana) 32328 40.29 125 Melia azedarach (seringa) 14224 7.34 52 Opuntia spp. (cacti) 95010 7.70 8 Pinus spp. (pine trees) 132937 272.31 205 Populus spp. (poplars) 58082 26.89 46 Prosopis spp. (mesquite) 5232 1.95 37 Psidium guajava (guava) 6354 7.16 113 Rosa rubiginosa (eglantine) 11801 8.75 74 Salix babylonica (weeping willow) 37555 22.48 60 Senna didymobotrya (peanut butter cassia) 11586 13.84 119 Sesbania punicea (red sesbania) 1683 2.22 132 Solanum mauritianum (bugweed) 40413 58.20 144 Tamarix chinensis (Chinese tamarisk) 2137 7.13 334 Total 1494867 1443.56 97 Projected invasions: The initial estimates of the costs of control and the impacts of invasions were based on an increase of 5% per year (e.g. Le Maitre et al., 2002) but a synthesis of the information on spread suggests a rate closer to 10% (Van Wilgen & Le Maitre 2013). Projections of the impacts based on increases in invasions in the area of the catchments under natural vegetation show that the impacts are likely to become substantially greater. At an expansion rate of 5%, and densifi cation of 1%, the total reduction would increase to 2589 million m3/yr (5.2% of MAR) in 25 years (i.e. in about 2032). At 10% the projected reductions in 25 years will be about 3153 million m3/yr (6.3% of MAR). The increases in the percentage reductions occur throughout the mapped area but are greatest in the higher rainfall parts of the Eastern Cape, Kwa-Zulu-Natal and the Western Cape. The simple spread model did not allow invasions in a catchment to spread to adjacent ones that were not initially invaded so the estimated impacts probably are conservative. These fi ndings have signifi cant implications for water security within and downstream of these invaded areas, highlighting the need to focus investment in areas where it will yield the greatest long-term benefi ts. 83 CHAPTER 5 I THE STATUS OF INVADED AREAS FIGURE 5.4 Projected reductions in the mean annual runoff (MAR) in 2032, at diff erent rates of spread of invasive alien plants (assumed to be 5% in upper map and 10% in lower map). Map: D Le Maitre unpublished data. 84 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 5.5.2. Impacts on rangeland productivity by biome The impact of invasive alien plants on grazing potential was assessed for the Fynbos, Grassland, Succulent Karoo, Nama Karoo and combined Savanna and Thicket biomes by Van Wilgen et al. (2008). They used estimates of the mean livestock production to represent the potential of un-invaded vegetation to support livestock production, and maps of the extent of invasion by alien plant species to estimate reductions in livestock production in each biome. They estimated that current reductions in the potential of biomes to support grazing stock, as a result invasive alien plant infestations, amounted to between 200 (in the Nama Karoo) and 74500 (in the Fynbos) large stock units. This amounted to just over 1% of the potential number of livestock that could be supported by these ecosystems. However, they also estimated that these impacts could increase to 71% of the potential, if infestations of invasive alien plants were allowed to reach their full potential. They noted that “while the errors in these estimates could be large, the predicted impacts are of suffi cient magnitude to suggest that, even with signifi cant over-estimates, there is cause for serious concern; for example, even if the levels of impact are one tenth of those predicted, they would result in signifi cant losses of benefi t”. 5.5.3. Impacts on biodiversity intactness by biome The impact of invasive alien plants on biodiversity intactness was also assessed for the Fynbos, Grassland, Succulent Karoo, Nama Karoo and combined Savanna and Thicket biomes by Van Wilgen et al. (2008). Biodiversity intactness (Scholes & Biggs, 2005) estimates the impact of land-use changes (in this case invasion by alien plants) on populations of plants, mammals, birds, reptiles and frogs in a given area, and was designed to provide an easy-to-understand measure of the state of biodiversity for policy-makers and the public. A previous study by (Biggs, Reyers & Scholes 2006) had estimated that the biodiversity intactness index range from 71% to 89% for the fi ve biomes analysed. These estimates took the conversion of natural landscapes by means of agriculture, forestry or urban development, as well as land degradation into account, but they did not account for the impacts of invasive alien plants. When the additional impacts of invasive alien plants were considered, estimates of the current levels for the biodiversity intactness index only declined in the Fynbos biome (from 73% to 70%). It was concluded (Van Wilgen et al.. 2008) that this refl ected the fact that the fynbos biome had the highest levels of alien plant infestations, probably due to the considerably longer period of colonial settlement in the fynbos. Under a scenario where invasive alien plants are allowed to reach their full potential, however, the values were predicted to decline dramatically, to around 30% for the savanna, fynbos and grassland biomes, but to even lower values (13% and 4%) for the two karoo biomes, suggesting signifi cant potential declines in biodiversity of > 90% in places. 5.5.4. Impacts on fi re regimes Invasion of natural ecosystems by alien plants can change the structure and biomass of vegetation, adding fuel and supporting fi res of higher intensity. The productivity of rangelands is under serious threat from a large number of invasive plants that could potentially halve the production of livestock from natural rangeland areas. ½ 85 CHAPTER 5 I THE STATUS OF INVADED AREAS Increased fi re intensity can in turn increase the damage done by fi res, as well as the diffi culty of controlling fi res. Although the principles behind this phenomenon have been understood for some time (Brooks et al., 2004), there is very little in the way of documented impacts in South Africa. Van Wilgen & Richardson (1985) found that invasion of Fynbos shrublands by the shrubs Hakea sericea (silky hakea) and Acacia saligna (Port Jackson willow) increased fuel biomass by between 50 and 60%, but that this could not be shown to increase fi re intensity in an existing fi re behaviour prediction model. These authors concluded that shortcomings in the model prevented the accurate simulation of high intensity fi res which were known to occur in invaded stands under severe fi re weather conditions. Such fi res vigorously consume the increased biomass of shrub crowns, and are diffi cult to control. Later work demonstrated that physical damage to the soil can occur after fi re in invaded areas, resulting in increased erosion after fi re. For example, 6 tonnes of soil per hectare was lost following fi res in pine plantations compared to 0.1 tonnes per hectare following fi re in adjacent Fynbos in the Western Cape (Scott, Versfeld, Lesch 1998). While pine plantations are not strictly equivalent to invaded sites, the comparison is valid as plantations are normally established in Fynbos sites with almost no soil. A further study (Van Wilgen & Scott, 2001) compared soil damage following fi res in vegetation invaded to diff erent degrees on the Cape Peninsula. This study found a relationship between the degree of invasion and the physical damage to the soil, especially between sites that were uninvaded, or lightly invaded, compared to heavily invaded sites. Invasions of fi re-prone areas by large trees and shrubs can therefore be expected to result in severe soil damage and erosion. 5.5.5. Impacts on marine habitats As the most widespread and abundant marine invaders [Mytilus galloprovincialis (Mediterranean mussel), Semimytilus algosus (pacifi c mussel) and Balanus glandula (Pacifi c barnacle)] occur on rocky shores, this habitat is considered to be highly impacted. These impacts are focused on the west and south coasts where these species occur, and rocky shores along the east coast are not aff ected in the same way. Because of the impacts associated with Ficopomatus enigmaticus (estuarine tube-worm) in estuaries, this habitat is considered to be moderately impacted, while harbour environments experience low impacts. These results should be carefully considered because they represent the impacts of only 14% of marine alien species. These estimates might change once impacts of more species are understood. 5.6. SYNTHESIS AND INDICATOR VALUES There are relatively reliable data on species richness for invasive plants at national, provincial and biome scales. While some conservation agencies have provided information about the extent to which protected areas under their management have been invaded by alien species, there has not been any consistent monitoring of alien species within a standardised set of spatial units in South Africa, despite the existence of several attempts to map the extent of invasions (Box 5.1). It is still not possible to provide estimates of Relative invasive abundance for most areas (e.g. Van Wilgen et al., 2016). Estimating the level of invasion by alien species in particular areas could only be made with a low degree of certainty, given the relative lack of reliable and comprehensive data on invasive species. Even at the scale of protected areas, information on the level of invasions is at best scattered and incomplete. Only South African National Parks and two of the nine provincial conservation agencies (Cape Nature and Ezemvelo KwaZulu-Natal Wildlife) were able to provide lists of invasive species in protected areas under their jurisdiction, despite a longstanding legal requirement to develop such lists (Box 5.2). The level of completeness of these lists also varies. 86 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 There are few data on impacts. However, based on the existing studies, it appears that impacts are signifi cant (in particular on water resources), are set to grow rapidly as invasive species enter a phase of exponential growth, and the widespread negative impacts currently observed are a small fraction of what they will be if invasions were left unchecked. TABLE 5.6 Indicators used for reporting on the status of invaded areas. For full details of how to calculate the indicators, see Appendix 1. INDICATOR METRIC BASIC ADVANCED LEVEL OF CONFIDENCE NOTES 9. Alien species richness 9.1. Invasive species richness: Between 177 and 577 invasive species per province 9.2. Invasive animal species richness: 46–162 per half-degreegrid cell; Invasive bird species richness: 0–6 per QDGC; Invasive plant species richness: 0–165 per QDGC 9.3. Number of alien species at diff erent introduction stages per fi ner-degree national subdivision: Data not available 9.1. Moderate 9.2. Low for animals; moderate for birds and plants 10. Relative alien species richness 10.1. Relative invasive plant species richness per province ranged from 7% in the Northern Cape Province to 25% in the Northwest Province; no data for other taxa 10.2. Richness of alien species to indigenous species at diff erent introduction stages per fi ner-degree national subdivision: Data not available Low Distribution data for indigenous species are incomplete 11. Relative invasive abundance 11.1. Relative abundance in broad categories: No data 11.2. Proportion of abundance due to invasive species: No data N/A Abundance data are not available for either alien or indigenous taxa 12. Impact of invasions 12.1 Fynbos: major, massive and moderate impacts on water resources, rangeland productivity and biodiversity intactness respectively Grassland: moderate and minor impacts on water resources, and rangeland productivity respectively Savanna: Minor impacts on water resources 12.2. Surface water runoff reduced by between 1 and 321 million m3 per primary catchment Range productivity reductions are between 200 and 74500 large livestock units per year per terrestrial biome. Biodiversity intactness reduced by between 0 and 3% per biome 12.3. Estimated annual losses due to impacts on water resources, rangeland productivity and biodiversity amount to ZAR 5864, 337 and 428 million respectively. Low Estimates based on Van Wilgen et al. (2008) for 12.1 and 12.2, and on De Lange & Van Wilgen (2010) for 12.3 C. Percent of area experiencing major impacts C. 1.4% Low Based on the only available estimate of dense (“condensed”) cover invasive alien plants in South Africa 93 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES TABLE 6.1 Sources of data used to assign values to indicators of control eff ectiveness, with levels of confi dence based on the completeness and accuracy of data sets. The numbering of indicators is based on Chapter 2. Indicators are: 14. Money spent; 15. Planning coverage; 16. Pathways treated; 17. Species treated; 18. Area treated; 20. Eff ectiveness of species treatments; 21.Eff ectiveness of area treatments. DESCRIPTION SOURCE SCALE LEVEL OF CONFIDENCE BASED ON COMPLETENESS AND ACCURACY INDICATORS INFORMED BY THESE DATA Monitoring records from formal eradication projects South African National Biodiversity Institute National High 14,17 Estimates of the eff ectiveness of biological control agents in discrete categories (complete, substantial, negligible or not assessed) Regular reviews of invasive alien plant biological control (Moran, Hoff mann & Hill 2011) National High 17, 20 Descriptions of invasive species management programs Published scientifi c literature National Moderate 15 Spatial database of alien plant control projects, with information on species, area treated and costs (data used in most research projects assessing control eff ectiveness) Department of Environmental Aff airs, Working for Water Information Management System (WIMS) National Low 14, 17, 18 Records of eff ectiveness of alien freshwater fi sh control projects Cape Nature and South African Institute of Aquatic Biodiversity River system (only one to date, see Woodford et al., 2017). High 17, 20 Monitoring of feral pig control programme Cape Nature Localised Moderate 17, 20 Description of project to remove alien frog species (De Villiers et al., 2016) Published scientifi c literature Localised Moderate 17, 20 A range of studies assessing the eff ectiveness of alien plant control measures applied to particular areas Published scientifi c literature Studies were carried out at the scale of provinces, catchments, protected areas or privately-owned farms. Moderate 14, 17, 18, 20, 21 A range of studies assessing the returns on investment from alien plant control projects applied to particular areas or species Published scientifi c literature Limited to the range of the target species for biological control; Other studies at provincial or catchment scales Low 14, 20, 21 Interceptions at O.R. Tambo International Airport Records within the Department of Environmental Aff airs A single entry point Moderate 16 94 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 6.2. PATHWAY-RELATED CONTROL MEASURES Pathway-based control measures focus on reducing the risk of introducing damaging species (i.e. the actual mechanism by which species arrive, rather than specifi c species themselves). In invasion ecology, the term “dispersal pathways” is used broadly, and refers to the combination of processes and opportunities that result in the movement of alien species from one place to another. For example, organisms can be introduced by ships through a number of pathways (as stowaways in ballast water, in cargo containers, on the hull of the ship, or in the luggage of crew or passengers). In South Africa, intentional introductions are currently managed through a permitting system. Species require import permits that are based on a risk assessment conducted by a qualifi ed risk assessor. These assessments are then sent by the Department of Environmental Aff airs (DEA) to the Alien Species Risk Analysis Review Panel (ASRARP) for comment. ASRARP is a committee of experts set up in October 2016 to provide scientifi c oversight on decisions concerning biological invasions, and in particular to provide recommendations to DEA as to the quality and completeness of an invasive species risk assessment. DEA then makes a decision to approve or, should the risks be too high, reject an application for an import permit. The eff ectiveness of these permitting measures is covered in Chapter 7. For air traffi c, inspections by the DEA are currently only carried out at O.R. Tambo International Airport, where permit compliance is checked, illegal imports are intercepted and the luggage of tourists and cargo is searched for alien organisms that may have been unintentionally transported as stowaways. Occasional and infrequent joint operations are also carried out by DEA in conjunction with other departments at a limited number of other entry points. For shipping, the Marine Draft Ballast Water Bill aims to reduce the risk of the unintentional introduction of alien marine species through the release of ballast water by ships. This legislation has not yet been passed. While other control measures are in place to manage additional pathways of introduction, these focus on potential agricultural pests (e.g. phytosanitary inspections at border posts) or threats to human health (e.g. spraying the interior of aircrafts to kill insect disease vectors). In line with international obligations under the International Plant Protection Convention (IPPC) and its role as the National Plant Protection Organization (NPPO), the Department of Agriculture, Forestry and Fisheries (DAFF) regulates and monitors the importation of agricultural goods. Interceptions are often not recorded or are not entered into a database, and such databases often focus only on quarantine organisms. Due to a lack of baseline data, increases in global travel and trade, and changes in patterns of demand, it is extremely diffi cult to demonstrate a direct link between control measures and changes in rates of introduction and establishment of alien species (Essl et al., 2015a). Furthermore, most of the pathway-related control measures in South Africa have not been in place for long enough to properly assess their eff ectiveness. For example, inspections at O.R. Tambo by the Biosecurity Unit of the DEA only commenced in 2015, and currently only operate on weekdays during offi ce hours (7:30-16:30). There were 24735 DEA inspections between April 2015 and January 2017 (346 of commercial cargo, none at the mail centre and 24388 at the terminals), and ten illegal imports and luggage stowaways were intercepted. Illegal imports can however enter the country almost unhindered through the remaining 71 formal ports of entry or after working hours and over weekends at O.R. Tambo airport. However, other 95 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES departments like DAFF and SARS-Customs are present at other ports of entry and sometimes identify instances of non-compliance and alert DEA biosecurity. Finally, although many alien species have been accidentally introduced to South Africa (Faulkner et al., 2016a; see also Chapter 3), no management is in place or has been considered for many of the pathways through which these alien species could enter the country. For example, vehicles (e.g. cars and trains) entering South Africa are not inspected for organisms transported as stowaways, and no measures are yet in place to prevent the introduction of marine species attached to the hulls of visiting ships. 6.3. SPECIES-SPECIFIC CONTROL MEASURES 6.3.1. The status of attempts at eradication The term “eradicate” is defi ned as the removal of all individuals and propagules from a specifi ed area (for the purposes of this report either the whole South Africa or any one of the off shore islands) where the likelihood of re-colonisation is negligible, i.e. a successful eradication will remove the need for future control measures. The terms “eradicate” or “eradication” are often incorrectly used in policy documents, control plans and legislation as synonyms for “control” or “manage”. In this section, the eff ectiveness of eradication attempts, where the goal of eradication was explicitly stated, is assessed. Pluess et al. (2012) reviewed a global set of 136 eradication campaigns against 75 species (invasive alien invertebrates, plants and plant pathogens) and examined whether certain factors could explain success. They found that only the spatial extent of the infestation was signifi cantly related to the eradication outcome, and that local campaigns were more successful than regional or national campaigns; a range of other factors were all unrelated to eradication success. As a result of their fi ndings, they recommended that eradication measures should generally concentrate on incursions when infestations are still relatively small, and the variability in success is likely down to diff erence in the quality of the project management, including factors like monitoring and reporting. Release of captive-bred biological control agents – Kim Weaver 96 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 It is also becoming increasingly clear that eradication measures need to be considered carefully before they are attempted, and that once they are initiated it is equally important that progress should be monitored and implementation should not be subject to the vagaries of funding cycles. In 2008, the Working for Water Programme funded the establishment of South African National Biodiversity Institute’s Invasive Species Programme (SANBI ISP). SANBI ISP was designed to detect and document new invasions, and to provide the cross-institutional coordination needed to successfully implement national eradication plans (Wilson et al., 2013). The focus of the unit was on species listed as category 1a under the A&IS Regulations, as well as on selected non-listed species. Candidate non-listed species were designated as ‘Species Under Surveillance – Possible Eradication or Containment Targets’ (SUSPECT). The SUSPECT list has no legal status, but it includes species where there is suffi cient documented evidence to warrant in-depth investigation and incursion response. New additions to the SUSPECT list must be accompanied by: (1) an initial risk assessment, (2) a specimen lodged in a South African collection, (3) a short background dossier on life-form and invasive tendencies elsewhere in the world, lodged with SANBI and (4) a detailed project plan including information on current distribution in South Africa, local-scale distribution for one or more naturalised populations, an assessment of management options and an outline of proposed research. This approach has been followed since 2012, and as a result a number of SUSPECT species have been targeted for eradication (Table 6.2). To date, 42 eradication projects have been initiated, or are under consideration, in South Africa (Table 6.2). Most of these (32) are aimed at terrestrial or freshwater plants. Of these projects, 23 are under consideration, pending the outcome of a risk analysis or the development of a detailed plan, and 10 are ongoing [eight against plants, one targeting a bird species (Corvus splendens, the house crow), and one targeting a mammal (Hemitragus jemlahicus, the Himalayan tahr) Table 6.3]. Of the completed historical projects, three were successful (one being the eradication of Felis catus, the domestic cat, from Marion Island, and the other two against terrestrial invertebrates). Six projects were deemed to have failed, three against plants, one against an amphibian, one against a freshwater invertebrate and one against a terrestrial invertebrate. TABLE 6.2 The status of eradication projects in South Africa. For species listed as invasive under the NEM:BA A&IS Regulations 2016, relevant categories are shown; unlisted species are also shown. SUSPECT species are those identifi ed as ‘Species Under Surveillance – Possible Eradication or Containment Targets’ (see text). The status of projects is either “Under consideration” (where a decision to proceed with eradication would depend on the outcome of a risk analysis or the development of a detailed plan); “ongoing” (where eradication attempts are under way, but where eradication has not yet been confi rmed); “failed” (where the species has persisted despite eradication attempts, such that the eradication attempt was discontinued); or “successful” (where the species was eradicated). TAXON SPECIES AND CATEGORY PROJECT STATUS NOTES Terrestrial and freshwater plants Acacia fi mbriata (fringed wattle) 1a Under consideration Removal of individuals from small populations commenced in 2012 Terrestrial and freshwater plants Acacia implexa (screw pod wattle) 1a Under consideration Removal of individuals from small populations commenced in 2012 (Kaplan et al., 2012) Terrestrial and freshwater plants Acacia paradoxa (kangaroo thorn) 1a Ongoing Removal of population on Table Mountain commenced in 2008 (Zenni et al., 2009). Cost to date ZAR 400000 97 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES TAXON SPECIES AND CATEGORY PROJECT STATUS NOTES Terrestrial and freshwater plants Acacia retinodes (swamp wattle) (SUSPECT) Under consideration Removal of individuals from small populations commenced in 2012 Terrestrial and freshwater plants Acacia stricta (hop wattle) 1a Under consideration Removal of individuals from small populations commenced in 2012 (Kaplan et al., 2014) Terrestrial and freshwater plants Acacia viscidula (sticky wattle) (SUSPECT) Under consideration Removal of individuals from small populations commenced in 2012 Terrestrial and freshwater plants Alhagi maurorum (camel thorn bush) 1b Failed Attempted eradication of camel thorn from irrigation schemes in 1960s Terrestrial and freshwater plants Anigozanthos fl avidus (yellow kangaroo paw) (SUSPECT) Unlisted Under consideration Clearing has started but progress has not been assessed (Le Roux et al., 2010). Landowner has expressed further interest in continuation of this work. New populations found at separate site on Agulhas Plain Terrestrial and freshwater plants Anigozanthos rufus (red kangaroo paw) (SUSPECT) Unlisted Under consideration Clearing has started but progress has not been assessed (Le Roux et al., 2010). Should possibly deal with Anigozanthos fl avidus and A. rufus as a single eradication attempt as there is hybridisation. Activities have not separated the two species or hybrids but dealt with them as a single attempt Invertebrate Bactrocera invadens (Asian fruit fl y) 1a Failed Despite reports on the eradication of the Asian fruit fl y from Limpopo Province in 2011 (Manrakhan, Venter & Hattingh 2015) the species is now widespread in the country Terrestrial and freshwater plants Banksia ericifolia (heath banksia) (SUSPECT) Under consideration A few small populations in the Western Cape (Geerts et al., 2013b) Terrestrial and freshwater plants Berberis julianae (Chinese barberry) Unlisted Under consideration Small populations in Northwest, Free State, KwaZulu-Natal and Western Cape; possibly present in Lesotho (Keet, Cindi & Du Preez 2016) Bird Corvus splendens (house crow) 1a Ongoing The population has been reduced from 10000 birds in 2009 to less than 400 birds by end of January 2016 in Cape Town. The eThekwini population is currently (2016) estimated at less than 5 birds, and no birds have been recorded as seen in the last 9 months Terrestrial and freshwater plants Epipremnum aureum (devil’s ivy) (SUSPECT) Under consideration Small populations present in KwaZulu-Natal (Moodley, Procheş & Wilson 2017) Mammal Felis catus (domestic cat) 1a (on islands) Successful Eradication of cats from Marion Island between 1973 and 1992 (Bester et al., 2002) 98 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 TAXON SPECIES AND CATEGORY PROJECT STATUS NOTES Terrestrial and freshwater plants Furcraea foetida (Mauritian hemp) 1a Under consideration Scattered small populations in Western and Eastern Cape, and KwaZulu-Natal. Henderson and Wilson (2017) recommend reclassifi cation as 1b Terrestrial and freshwater plants Genista monspessulana (Montpellier broom) 1a Under consideration Small populations present on the Cape Peninsula (Geerts et al., 2013a) Mammal Hemitragus jemlahicus (Himalayan tahr) 1b Ongoing There was an attempted eradication of the Himalayan tahr from Table Mountain, but eradication unconfi rmed Terrestrial and freshwater plants Hydrilla verticillata (hydrilla) 1a Ongoing Occurs in Pongolapoort Dam, on the border between KwaZulu-Natal and Swaziland. Cost to date ZAR 800000.00 (including research on biological control) (Klein, 2011; Coetzee, Hill & Schlange 2008) Terrestrial and freshwater plants Hydrocleys nymphoides (water poppy) 1a Under consideration Occurs at two sites in KwaZulu-Natal (Nxumalo et al., 2016) Terrestrial and freshwater plants Hypericum pseudohenryi (Henry’s St. John’s Wort) Unlisted Under consideration Several populations in KwaZulu-Natal Terrestrial and freshwater plants Iris pseudacorus (yellow fl ag) 1a Under consideration Found at several sites in Gauteng and KwaZuluNatal (Jaca & Mkhize 2015). Cost of control to date ZAR 621000.00. Terrestrial and freshwater plants Lythrum salicaria (purple loosestrife) 1a Ongoing Occurs along the Liesbeeck River in the city of Cape Town. Cost of control to date ZAR 435000.00. Terrestrial and freshwater plants Melaleuca hypericifolia (red-fl owering tea tree) 1a Ongoing One population on the Cape Peninsula. Clearing commenced in 2012 (Hickley et al., 2017) Terrestrial and freshwater plants Melaleuca parvistaminea (rough-barked honey-myrtle) (SUSPECT) Under consideration Small populations in the Western Cape; feasibility of eradication under assessment (Jacobs, Richardson & Wilson 2014) Terrestrial and freshwater plants Mimosa albida (common name unknown) Unlisted Under consideration One small population in KwaZulu-Natal (Cheek 2015) Terrestrial and freshwater plants Opuntia aurantiaca (jointed cactus) 1b Failed Attempted eradication of jointed cactus in the 1930s and 1940s (Moran & Annecke, 1979) Terrestrial and freshwater plants Opuntia salmiana (bur cactus) 1a Ongoing Small population being managed towards eradication in the Northwest Province. 99 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES TAXON SPECIES AND CATEGORY PROJECT STATUS NOTES Invertebrate Otala punctata (freckled edible snail) Unlisted Successful Eradication of the Mediterranean snail in the Western Cape between 1987 and 1989 at a cost of ZAR 215000 (1988 prices) (Herbert & Sirgel 2001) Terrestrial and freshwater plants Petiveria alliacea (Guinea hen-weed) Unlisted Under consideration Less than 1000 plants in the city of Durban (Cheek 2013) Invertebrate Polistes dominula (European paper wasp) 1b Under consideration Distribution currently limited to the Western Cape Province, where control is ongoing (Benadé et al., 2014) Invertebrate Procambarus clarkii (red swamp crayfi sh) Prohibited Failed Eradication was attempted in the Crocodile River, Mpumalanga in 1994, but the species has survived (Nunes et al., 2017) Terrestrial and freshwater plants Pueraria montana var. lobata (kudzu vine) 1a Ongoing Earlier attempted eradication of kudzu vine in Mpumalanga in the 1960s and 1970s failed. New attempt is being implemented by SANBI (Geerts et al., 2016) Terrestrial and freshwater plants Sagittaria latifolia (common arrowhead) Unlisted Ongoing Nine of the known ten populations have been cleared in KZN. Terrestrial and freshwater plants Sagittaria platyphylla (delta arrowhead) 1a Under consideration Scattered populations in four provinces Amphibian Sclerophrys gutturalis (African common toad) Unlisted Failed Attempt to extirpate the guttural toad on the Cape Peninsula (Vimercati et al, 2017; Measey et al., 2017) Terrestrial and freshwater plants Solanum elaeagnifolium (silver-leaf bitter apple) 1b Failed Attempted eradication of satansbos in the Northwest Province between 1952 and 1972 Terrestrial and freshwater plants Spartina alternifl ora (smooth cord grass) 1a Ongoing Attempted eradication in the Groot Brak Estuary (Adams, Van Wyk & Riddin 2016; Riddin, Van Wyk & Adams 2016) Terrestrial and freshwater plants Tephrocactus articulatus (pine cone cactus) 1a Under consideration Populations in the Northern, Western and Eastern Cape Provinces Terrestrial and freshwater plants Triplaris americana (ant tree) 1a Under consideration Less than 1000 plants in the city of Durban (Lala & Ivey, 2011) Invertebrate Trogoderma granarium (khapra beetle) 1b Successful Eradication of khapra beetle at multiple sites, most recently near Upington in 1972 Invertebrate Vespula germanica (German wasp) Under consideration The geographical range of the German wasp is now well documented and destructive sampling has been carried out since 2014 100 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 TABLE 6.3 Number of eradication projects attempted per high-level taxon in South Africa, with assessment of status STATUS TAXON TOTAL TERRESTRIAL AND FRESHWATER PLANTS MAMMALS BIRDS AMPHIBIANS TERRESTRIAL AND FRESHWATER INVERTEBRATES Under consideration 21 2 23 Initiated and ongoing 8 1 1 10 Successfully eradicated 1 2 3 Failed 3 1 2 6 Totals 32 2 1 1 6 42 6.3.2. Biological control of invasive plants Overview of eff ectiveness of biological control of alien plants. Biological control of invasive plants using introduced natural enemies has contributed signifi cantly to sustained, cost-eff ective management of several invasive plant species in South Africa. Biological control programmes have been launched or are under investigation for 77 invasive plant species. Many of the most obvious successes have been against acacias, cacti (Figure 6.1) and invasive aquatic plants, although successes have certainly not been limited to these groups. Henderson & Wilson (2017), in a review based on records in the Southern African Plant Invaders Atlas, concluded that “some [invasive plant] species which have been the subjects of successful biological control programmes have shown very little expansion in their distribution” and “in general successful biological control seems to be associated with a reduction in the rate of spread”. This is in stark contrast to species that have not been subjected to any biological control, where spread has accelerated in many cases. FIGURE 6.1 Cylindropuntia fulgida (chain-fruit cholla) in the Northern Cape Province. The right-hand panel shows the population after the introduction of the biological control agent Dactylopius tomentosus (cholla biotype, cochineal cladode sucker). Invasive plant species that are under biological control. Biological control agents have been established on 60 invasive plant species in South Africa (Table 6.4). Of these, 15 species (eight succulent cacti, four aquatic plants, two herbs and one shrub species) are under complete control; 19 species (nine tree or shrub species, eight succulent cacti, one aquatic plant and one herb) are under a substantial degree of control; a negligible degree of control has been achieved on 15 species (11 tree or shrub species, two herbs and two climbers); while the degree of control has not been determined for the remainder (three tree and shrub species, four succulent cacti, two herbs and two climbers). 101 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES TABLE 6.4 Invasive plant species on which biological control agents have been successfully established in South Africa, and the degree of biological control achieved as per the following categories: Complete: no other control measures are needed to reduce the invasive plant species to acceptable levels, at least in areas where the agents are established; Substantial: other methods are needed to reduce the invasive plant species to acceptable levels, but less eff ort is required (e.g. less frequent herbicide applications or less herbicide needed per unit area); Negligible: in spite of damage infl icted by the agents, control of the invasive plant species remains entirely reliant on the implementation of other control measures; and Not determined: either the release of the agents has been too recent for meaningful evaluation or the programme has not been evaluated. INVASIVE PLANT SPECIES LIFE FORM REGION OF ORIGIN DEGREE OF BIOLOGICAL CONTROL Acacia baileyana (Bailey’s wattle) Tree Australia Negligible Acacia cyclops (rooikrans) Tall shrub or tree Australia Substantial Acacia dealbata (silver wattle) Tree Australia Negligible Acacia decurrens (green wattle) Tree Australia Negligible Acacia longifolia (long-leaved wattle) Tree Australia Substantial Acacia mearnsii (black wattle) Tree Australia Substantial Acacia melanoxylon (Australian blackwood) Tree Australia Substantial Acacia podalyriifolia (pearl acacia) Tree Australia Negligible Acacia pycnantha (golden wattle) Tree Australia Substantial Acacia saligna (Port Jackson) Tree Australia Substantial Ageratina adenophora (Crofton weed) Perennial herb Central America Negligible Ageratina riparia (mistfl ower) Perennial herb Central America Complete Austrocylindropuntia subulata (long spine cactus) Succulent shrub South America Not determined Azolla fi liculoides (Azolla) Free-fl oating aquatic plant South America Complete Caesalpinia decapetala (Mauritius thorn) Thorny evergreen shrub or climber Asia Negligible Campuloclinium macrocephalum (pompom weed) Shrub South America Not determined Cardiospermum grandifl orum (balloon vine) Perennial slightly woody climber South America Not determined Cereus hildmannianus (queen of the night) Spiny succulent tree South America Complete Cereus jamacaru (queen of the night) Spiny succulent tree South America Complete Chromolaena odorata (triffi d weed) Shrub North, Central & South America Not determined Cirsium vulgare (spear thistle) Spiny herbaceous biennial Europe Negligible Cylindropuntia fulgida (chain-fruit cholla) Compact spiny succulent shrub North & Central America Complete Cylindropuntia fulgida var. mamillata (boxing-glove cactus) Compact spiny succulent shrub South America Complete Cylindropuntia imbricata (imbricate cactus) Spiny succulent shrub North & Central America Substantial Cylindropuntia leptocaulis (pencil cactus) Compact spiny succulent shrub North & Central America Complete Dolichandra unguis-cati (cat’s claw creeper) Woody-stemmed climber Central & South America Negligible Eichhornia crassipes (water hyacinth) Free-fl oating aquatic herb South America Substantial Gleditsia triacanthos (honey locust) Spreading tree North America Not determined 102 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 INVASIVE PLANT SPECIES LIFE FORM REGION OF ORIGIN DEGREE OF BIOLOGICAL CONTROL Hakea gibbosa (rock hakea) Tall shrub Australia Negligible Hakea sericea (silky hakea) Tall shrub Australia Substantial Harrisia balansae (strangler prickly apple) Spiny succulent shrub South America Substantial Harrisia martinii (moon cactus) Spiny succulent shrub South America Complete Harrisia pomanensis (midnight lady) Spiny succulent shrub South America Substantial Harrisia tortuosa (spiny snake cactus) Spiny succulent shrub South America Substantial Hylocereus undatus (night-blooming cereus) Vine-like cactus Tropical America Not determined Hypericum perforatum (St John’s wort) Perennial herb Europe & Asia Complete Lantana camara (lantana) Shrub Central & South America Negligible (Highveld) to substantial (coastal & Lowveld) Leptospermum laevigatum (Australian myrtle) Tall shrub or tree Australia Negligible Leucaena leucocephala (leucaena) Shrub or small tree Tropical America Negligible Myriophyllum aquaticum (parrot’s feather) Rooted aquatic herb South America Complete Opuntia aurantiaca (jointed cactus) Spiny succulent shrublet South America Substantial Opuntia engelmannii (small round-leaved prickly pear) Succulent shrub North & Central America Negligible Opuntia fi cus-indica (mission prickly pear) Succulent tree or shrub Central America Substantial Opuntia humifusa (large-fl owered prickly pear) Succulent low shrublet North America Complete Opuntia monacantha (drooping prickly pear) Succulent shrub or tree South America Complete Opuntia salmiana (bur cactus) Succulent shrub South America Substantial Opuntia spinulifera (large round-leaved prickly pear) Succulent shrub Central America Not determined Opuntia stricta (Australian pest pear) Spiny succulent shrub North America & Caribbean Substantial Paraserianthes lophantha (stink bean) Tree Australia Substantial Parthenium hysterophorus (famine weed) Annual shrub Caribbean Not determined Peniocereus serpentinus (serpent cactus) Succulent shrub Mexico Not determined Pereskia aculeata (Barbados gooseberry) Spiny shrubby to clambering vine South America & Caribbean Not determined Pistia stratiotes (water lettuce) Free-fl oating aquatic herb South America Complete Prosopis species (mesquite) Tree North & Central America Negligible Salvinia molesta (water fern) Free-fl oating aquatic fern South America Complete Sesbania punicea (red sesbania) Shrub South America Complete Solanum elaeagnifolium (silverleaf bitter apple) Herbaceous shrublet North, Central & South America Substantial Solanum mauritianum (bugweed) Tree South America Negligible Solanum sysimbriifolium (wild tomato) Spiny low shrub South America Substantial Tecoma stans (yellow bells) Tree North & Central America Not determined 109 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES 6.4.2. Assessments of control eff ectiveness at fi ner scales where information is available The eff ectiveness of control measures in a particular area (for example a protected area, a catchment area, a farm, or a stretch of river) would need to be assessed against the intended goals of the measure. In addition, the assessment should be based on regular monitoring of outcomes. Almost all area-based control measures are aimed at alien plant species, and most have the goal of reaching a “maintenance level”, although this goal is seldom explicitly stated (Van Wilgen et al., 2016a; Fill et al., 2017). The concept of a maintenance level recognises that, for many invasions, eradication is infeasible, but that they can be reduced to a level where the negative impacts are negligible and control costs are relatively low in perpetuity. This was defi ned by Goodall & Naude (1998) as “the systematic reduction of the major invasive alien plant species in defi ned tracts of land to a level where they no longer present a problem”. In South Africa, as in many other parts of the world, the intended goals of control measures are predominantly not explicit. In the vast majority of South Africa’s government-funded alien plant control projects, the indicators used to monitor progress and set targets include the amounts of money to be spent, the number of people to be employed, and the areas to be treated. These are input or output indicators, rather than outcomes in terms of changes in the levels of plant invasions. In the absence of a monitoring programme that is focussed on outcomes, it is diffi cult to assess eff ectiveness objectively. However, several studies have been conducted, particularly over the past decade, in which the eff ectiveness of management has been assessed, and these are presented and summarised here in chronological order. These studies provide a limited basis from which to derive broad conclusions about the eff ectiveness of control measures. Alien plant control in the Cape of Good Hope Nature Reserve, Western Cape Province, 1941-1987 (Macdonald, Clark & Taylor 1989). The Cape of Good Hope Nature Reserve is a fynbos shrubland area now incorporated into the Table Mountain National Park. It was historically heavily invaded by alien trees and shrubs, and control operations started in 1943. These proved to be almost totally ineff ective for at least the fi rst 35 years; no systematic control strategy was implemented, follow-up and control was inadequate to prevent re-establishment of felled thickets and the supervision of control teams was defi cient. Linkage of control operations to fi rewood production was a signifi cant factor in this failure. In 1974 a 10-year control strategy was drawn up and later began to be eff ectively implemented. Surveys of 40 plots in the centre of the reserve in 1966, 1976–1980 and 1986 showed increasing densities of species other than the easily controlled P. pinaster up to 1976–1980. Since then almost all individual alien plants taller than 1.8 m in height were eliminated and indications from smaller height classes are that seed banks were depleted. This study provided an early indication of the value of a strategic approach to alien plant control. Management of Prosopis species (mesquite) in the Northern Cape Province (Van den Berg, 2010; Wise, Van Wilgen &Le Maitre, 2012; Van Wilgen et al., 2012). Trees in the genus Prosopis (mesquite) were introduced to provide a source of fodder for livestock in the arid areas of South Africa. They later became invasive, spreading over large areas and causing many negative impacts. Historical estimates for the rate of spread of Prosopis trees in South Africa ranged from 3.5 to 18% per year, which implied that the invaded area could double every 5 to 8 years. In the Northern Cape, the estimated total invaded area increased by almost a million hectares between 2002 and 2007, which is equivalent to 27.5% per year, and this occurred at a time during which ZAR 390 million (2012 values) was spent on control. Overall, it was concluded that estimated control costs would exceed the fi nancial capabilities of Public Works programmes, and that more eff ective control methods, such as biological control, would be needed to prevent substantial INPUTS TO CONTROL The amount spent by the DEA per year on control operations is at least R1.5 BILLION 110 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 economic losses. A more recent update (R.T. Shackleton unpublished data) found that the public works clearing projects had treated 203000 ha of the area invaded by Prosopis between 2000 and 2015 (clearing consisted of an initial clearing and three follow-up clearings, on average, to remove seedlings). The cost of these measures amounted to ZAR 1.8 billion (R 4.2 billion expressed in 2016-value ZAR, or over ZAR 2000/ha treated) over the same period. The project started in 1995, but cost estimates prior to the year 2000 are not available. These fi gures also excluded the cost of researching and introducing the three biological control agents, as well as private landowner control costs which averages around ZAR 21000 per farm per year (Shackleton, Le Maitre & Richardson 2015). Between 2000 and 2016, Prosopis glandulosa, and Prosopis hybrids increased their range from 40 to 112, and 390 to 481 quarter-degree grid cells, increases of 50 and 180% respectively (Henderson & Wilson, 2017), suggesting that substantial control measures were doing little to stop the spread of this damaging species. Cost-eff ectiveness of alien plant clearing in the Krom and Kouga River catchments, Eastern Cape Province (McConnachie et al., 2012). This assessment was carried out in the Krom (1556 km2) and Kouga (2426 km2) catchments in the Eastern Cape Province. It concluded that the cost to clear invaded land was 2.4 times higher than the highest equivalent estimate made elsewhere in South Africa. At rates of clearing at the time of the study, it would have taken between 54 and 695 years to clear the catchments, in the Krom and Kouga, respectively, assuming no further spread. By taking ongoing spread into account, it was apparent that current control measures would be inadequate, and invasions would most likely continue to spread in the catchments. The study also found signifi cant ineffi ciencies in the form of inaccurate records, where 25% of the areas recorded as having been cleared had in fact not been cleared. Historical costs and future scenarios for alien plant control in protected areas in the Cape Floristic Region (Van Wilgen et al., 2016). This study sought to document the extent and costs of substantial control eff orts in the Cape Floristic Region (CFR) over the past two decades, and to estimate the resources that would be needed to reduce the problem to a “maintenance level” at which it could be sustainably contained in perpetuity. Historical costs for control in CFR protected areas between 1996 and 2015 amounted to ZAR 564 million (2015 values). Predicting future control eff ectiveness required a number of assumptions to be made about the future funding levels, rates of spread, and the eff ort that would be required to bring alien plants down to a maintenance level. The study concluded that, for scenarios in which control measures continued against all invasive plant species, the estimated required funding to achieve the goal of reducing invasions to a manageable level was up to 4.6 times greater than the amount spent over the past 20 years. Under many plausible future scenarios (for example 8% spread and current or reduced funding) the invaded area would continue to grow, despite signifi cant ongoing spending. Eff ectiveness of alien plant clearing in the Berg River catchment in the Western Cape Province (Fill et al., 2017). This study assessed alien plant (mainly Pinus and Acacia) control activities in the Berg River catchment in the Western Cape Province. Control operations took place over 13 years, at a cost of ZAR 50 million (net present value in 2015 ZAR), and succeeded in greatly reducing the cover of alien plants, but not to a maintenance level. At the time of assessment, over 1000 ha still supported dense or medium invasions (> 25% cover), and the area occupied by scattered Pinus plants had increased by over 3000 ha to >5700 ha (Figure 6.2). While the project is ongoing, it was concluded that the entire area would revert to a more densely-invaded state in the event of a reduction of funding, given that a signifi cant population of invasive plants of all species remained present in fairly large numbers. The study pointed to several factors that had contributed to ineffi ciencies, including the lack of a plan, a failure to integrate prescribed burning and mechanical clearing, a failure to co-ordinate high-altitude clearing with other operations, and the use of (relatively ineffi cient) hand tools instead of power tools. 111 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES Pinus Dense Medium Low Scattered 2001 2014 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 Area (ha) Acacia Dense Medium Low Scattered 2001 2014 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 Area (ha) FIGURE 6.2 Area occupied by alien Pinus and Acacia trees at diff erent levels of cover in the upper Berg River catchment at the initiation of a control project in 2001, and after 13 years of treatments in 2014. Cover levels are dense (> 50% cover), medium (26–50% cover), low (6–25% cover) and scattered (0.5–5.0% cover). Figure redrawn from Fill et al. (2017). Alien plant control projects in the Hawequas Mountain complex in the Western Cape Province (McConnachie et al., 2016). This study took place in the Hawequas Mountain Fynbos complex, an area covering 1451 km2 in the south-western part of the Western Cape Province. The area had been subjected to alien plant control operations over several years, including the removal of abandoned pine plantations. Control reduced cover – it was estimated that the proportion of the area covered by invasive trees would have been almost 50% higher had there been no control. However, the costs were three to fi ve times higher than the predictions made when the programme was initiated. It was concluded that control might have prevented a larger area from being invaded, if it had focussed all of its eff ort on untransformed land and not on abandoned plantations. Effi ciency of invasive alien plant management in the Garden Route National Park (GRNP), Western and Eastern Cape Province (Kraaij et al., 2017). The GRNP is situated along the southern Cape coast of South Africa between the Indian Ocean in the south and the watershed of the Outeniqua and Tsitsikamma Mountains in the north, extending over 152500 ha of which ~78 000 ha comprises fi re-prone fynbos shrublands and ~41500 ha comprises Afrotemperate forest. The fynbos areas were substantially invaded by trees and shrubs in the genera Acacia, Hakea and Pinus. Invasive alien plant control operations had been active in the park since 1995. The study set out to assess the effi ciency of alien plant management practices in the fi eld. Parts of the GRNP have a long history of alien plant control operations, but comprehensive strategic planning, prioritisation and improved monitoring had only recently been initiated. The study sought to investigate the alignment of implementation with management plans, and the eff ectiveness of alien plant clearing practices in the fi eld. The study found that, although detailed management plans were developed, implementation was poorly aligned with plans. The quality of many treatments was found to be inadequate, with work done to standard in only 23% of the assessed area. Problems encountered included a complete absence of treatment application despite payment of contractors (33% of assessed area); partial treatment of areas (38%), species (11%) or age classes (8%), leaving 112 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 others untreated; use of inappropriate treatment methods (9%); and failure to adhere to treatment standards (7%). Accordingly, successive follow-up treatments largely did not reduce the cover of invasive plants. Field surveys and clearing records suggested that inaccurate (or lack of) infi eld estimation of cover prior to contract generation resulted in an erroneous estimation of eff ort required, and expenditure disparate with required norms. This study points to substantial ineffi ciencies in the application of control methods, and identifi ed the need for rigorous, compulsory, infi eld assessment of invasive plant cover prior to contract allocation and assessment of the quality of treatments applied prior to payment of contractors. Managing invasive plants on Vergelegen Wine Estates in the Western Cape Province (Van Rensburg, Richardson & Van Wilgen 2017). This study took place on the privately-owned Vergelegen Estate (5332 ha) in the Hottentots Holland Mountain Range Basin near the town of Somerset West in the Western Cape. The area had become substantially invaded by trees and shrubs in the genera Acacia, Hakea and Pinus. Invasive plant control operations commenced in 2004, and the study assessed their cost and eff ectiveness over more than a decade. The assessment showed that the cover of dense invasive plants declined by 70% over the 10 years since management operations began (Table 6.3), but that operations cost 3.6 times more than was originally estimated (ZAR 43.6 vs 12.19 million respectively). The challenges associated with managing invasive plants on private land were very similar to those faced on state-owned land, with the effi ciency of management being constrained by multiple interacting environmental and socio-economic factors. However, some success in managing the invasions was achieved by adhering to best practice approaches, including careful planning with clear achievable goals in mind, a commitment to stable long-term funding, and regular monitoring. Closed Dense Medium Scattered Very Scattered Occasional Area (ha) 2004 2015 00 500 1000 1500 2000 2500 3000 3500 FIGURE 6.3 Area occupied by invasive plants in six cover classes at Vergelegen Wine Estates in 2004 and 2015. The classes are occasional (< 1% cover); very scattered (1–5% cover); scattered (5–25% cover); medium (25–50% cover); dense (50–75% cover); and closed (> 75% cover). Figure redrawn from Van Rensburg, Richardson & Van Wilgen (2017). 113 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES Alien plant control and ecosystem recovery along the Rondegat River in the Western Cape Province “(Fill, KritzingerKlopper & Van Wilgen 2017). The study took place along the Rondegat River, which fl ows in a north-westerly direction for 28 km from its source in the Cederberg Wilderness Area to its confl uence with the Olifants River at the Clanwilliam Dam. The river was invaded by dense stands of alien trees, mainly black wattle (Acacia mearnsii), blackwood (Acacia melanoxylon) and gum trees (Eucalyptus grandis). A project to clear these invasive species was initiated in 2013. The study aimed to review the land-use practices both on the project site and on adjacent areas, and examine how they could aff ect the project’s success over the long term. The assessment revealed recovery of indigenous riparian shrubs after clearing of dense stands of Acacia mearnsii, but also that grasses became dominant on cleared sites and in pastures. This study concluded that secondary invasions, especially by grasses, can have strong eff ects on ecosystem dynamics and that achieving the goals of restoration may therefore require additional active management. Invasive plant control in the Kruger National Park (KNP), Mpumalanga and Limpopo Provinces (Van Wilgen et al., 2017). The KNP is one of few protected areas in South Africa that has had a long history of controlling invasive species, particularly plants. Attempts to control alien plants in the KNP began in the mid-1950s, and expanded substantially in the late 1990s. The study sought to document the goals of alien plant management and the plans for achieving them; to identify the species targeted for control and the historical costs of their management; and to document and assess the eff ectiveness of the management interventions. This assessment reported that over ZAR 300 million had been spent on control interventions between 1997 and 2016. There was evidence of good progress with the control of several species, notably Opuntia stricta (Australian pest pear), Sesbania punicea (red sesbania), Lantana camara (lantana) and several invasive aquatic plant species, mainly because of eff ective biological control. On the other hand, over one third (38%) of the funding was spent on species that have subsequently been recognised as being of lower priority, most of which were alien annuals. The allocation of funds to non-priority species was sometimes driven by the need to meet additional objectives (such as employment creation), or by perceptions about relative impact in the absence of documented evidence. Management goals were also limited to inputs (funds disbursed, employment created) or outputs (area treated) rather than ecological outcomes, and progress was consequently not adequately monitored. The study recommended that funds should be re-directed to those species that clearly pose greater threats, and for which other solutions (such as biological control) are not an option. Control of invasive Chromolaena odorata (triffi d weed) in the Hluhluwe-iMfolozi Park, KwaZulu-Natal Province (Dew et al., 2017; Te Beest et al., 2017). This study took place in the 90000 ha Hluhluwe-iMfolozi Park (HiP) in KwaZuluNatal, South Africa. Infestations of Chromolaena odorata were fi rst noticed in 1978, and increased to cover almost half of the HiP (40000 ha) in 2003. After a substantial investment in control (ZAR 103 million in funding and 2000 person-years of eff ort), invasions were reduced to acceptably low levels by 2011 (Figure 6.4). A number of clear factors contributed to this success. They included ongoing direction from a diverse project steering committee (including managers, researchers, the private sector and community representatives), a rapid response team, a focus on areas of low infestation, a very fl exible management approach, regular monitoring and generous funding. In addition, Te Beest et al. (2017) reported that “the team was only paid following completion of a contract and after a thorough inspection of the quality of the work by the Project Manager”. These features of the HiP project are often in marked contrast to those associated with most other studies outlined above, and in all likelihood account for the diff erences in success. This work was, however, essentially a species management programme applied to a specifi c area, and the control of other invasive taxa was not documented. 114 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 Area (ha) Initial ha cleared Invaded Follow-up ha cleared 60 000 50 000 40 000 30 000 20 000 10 000 0 1978 1980 1981 1982 1983 1987 1988 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 FIGURE 6.4 Area invaded by Chromolaena odorata in Hluhluwe-iMfolozi Park, and areas cleared and followed up between 2000 and 2013. Figure redrawn from Te Beest et al. (2017). Control of invasive Chromolaena odorata (triffi d weed) in the Paradise Valley and Roosfontein Nature Reserves, KwaZulu-Natal Province (Adam, Ngetara & Ramdhani 2017). This remote sensing study took place in the Paradise Valley and Roosfontein Nature Reserves in KwaZulu-Natal, each approximately 300 ha. It was estimated that control operations reduced the extent of invasions from 154 to 3 ha between 2010 and 2015. No further information was given, so the methods employed in control, and the cost of the operations is not known. Again this work was essentially a species management programme applied to a specifi c area, and the control of other invasive taxa was not documented. 6.4.3. Returns on investment from control measures The economic costs of plant invasions, and the economic benefi ts of control, have also been the subject of a small number of studies in South Africa. The level of understanding of impacts and their economic costs is low, but estimates indicate that the cost of some impacts (lost water, grazing and biodiversity) is currently about ZAR 6.5 billion per annum, but could become much higher as invasions grow (De Lange & Van Wilgen, 2010). In the case of biological control of invasive plants, all studies have estimated very high returns on investment. By comparing the costs of biological control research and implementation to the benefi ts of restored ecosystem services, or avoided ecosystem degradation, and avoided ongoing control costs, biological control was shown to be extremely benefi cial in economic terms, with estimated benefi t:cost ratios ranging from 8:1 up to 3726:1 (Van Wilgen & De Lange, 2011). In order to estimate a return on investment from past mechanical and chemical alien plant control measures at a national scale, it would be necessary to know both the historic cost of control, and the value of impacts avoided due to control. De Lange & Van Wilgen (2010) provided a crude estimate of the area that remained free of invasions due to all historic control eff orts in South Africa, but because there were large assumptions in making this estimate, the level of certainty regarding the estimate is very low. The estimated value of potential ecosystem services (water, grazing and biodiversity) amounted to ZAR 152 billion annually (2008 ZAR values, De Lange & 115 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES Van Wilgen, 2010). Although an estimated ZAR 6.5 billion was lost every year due to invading alien plants, this would have been an estimated additional ZAR 41.7 billion per year had no control been carried out (as invasions would have been far more widespread). This indicates a saving of ZAR 35.2 billion every year due to the eff ects of historic control eff orts, but little confi dence can be placed in this estimate due to large and untested assumptions used in making the estimate. It does however suggest that, potentially, returns on investment into invasive species control projects could be very large. At a fi ner scale, some studies have estimated returns on investment from catchment-scale alien plant control projects. Hosking & Du Preez (2004) conducted cost-benefi t analyses at six sites (Tsitsikamma, Kouga, Port Elizabeth Driftsands, Albany, Kat River and Pott River), and concluded that “catchment management on all the sites carried out by the Working for Water Programme is ineffi cient”, with benefi t:cost ratios ranging between 0.03 and 0.75, which indicates a negative return on investment (though the benefi ts of job creation were not included). Van Wilgen et al. (1997) modelled the spread and eff ects of alien plants on streamfl ow in the 8000 ha Berg River catchment (Western Cape), and concluded that such management would be “eff ective and effi cient”. They estimated that water could be delivered at a cost of 57 and 59 c/kl respectively, with and without the management of alien plants, indicating that such management would be cost-eff ective. The estimate was based on projected clearing costs of around ZAR 180000 per year for initial clearing over ten years, and about ZAR 25000 per year for maintenance thereafter (1997 values). Fill et al. (2017) subsequently reviewed the actual costs and eff ectiveness of control operations over the past 20 years in the catchment of the Berg River. Their study found that the cost of control had amounted to almost ZAR 50 million by 2015 (2015 values, 7.2 times greater than the net present value of costs estimated in 1997), and that although the cover of alien plants was greatly reduced, over 1000 ha still supported dense or medium invasions (> 25% cover), and the area occupied by scattered Pinus plants had increased by over 3000 ha to > 5700 ha. It appears therefore that the projected effi ciencies were not realised, both because the control costs were underestimated, and because control methods were not eff ectively applied (Fill et al., 2017). Finally, there have been several recent studies on the potential returns on investment from invasive plant control operations (Vundla et al., 2016; Mudavanhu, Blignaut & Nkambule 2016; Morokong et al., 2016; Nkambule et al., 2017). These studies were conducted by ASSET Research, an African-initiated and led research and development platform (http://www.assetresearch.org.za/). The studies took place in the northern KwaZulu-Natal, Mpumalanga, Western Cape and Eastern Cape Provinces, where the economic viability of a range of management scenarios was modelled into the future. The scenarios included a range of rates at which invasive plants could spread in the future, as well as scenarios with and without the inclusion of value-added products derived from the processing of biomass from invasive plants, and with or without co-funding from the private sector. The results typically suggested that the inclusion of value-added products, and of co-funding, delivered higher, and positive, returns on investment, and that a “do nothing” scenario would deliver negative net present values. These studies suggest that the operations could be fi nancially viable in future, if the underlying assumptions behind the models are valid. These assumptions included: 1. That clearing will continue into the future, and will be carried out eff ectively and professionally; 2. That co-fi nancing will be available; 3. That there will be due compensation for the services rendered and the value-added products produced; 4. That the estimates of invaded area (derived from mapping exercises) are accurate; and, 5. That the resources required to complete the projects have been accurately estimated. 116 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 It is unlikely, however, that most or even all of the above assumptions hold. There is a low level of confi dence in the mapping of plant invasions (see Box 5.1); the costs of control eff ort required are routinely under-estimated by 3–7 times (see above); alien plant control work is often characterised by low levels of effi ciency; and the inclusion of value-added products could lead to unintended consequences (Box 6.3). There is consequently a low level of confi dence in these predictions. 6.4.4. Negative impacts of control The use of control measures are not without potential negative non-target impacts. These eff ects have not been assessed in this report, but should be a key component of future reports (Chapter 8). 6.5. SYNTHESIS AND INDICATOR VALUES 6.5.1. Overall eff ectiveness of control measures This assessment of the eff ectiveness of control measures has highlighted a number of points. It would clearly be benefi cial to gain control of invasive species because of the substantial economic costs that would accompany widespread, rampant invasions (Box 6.1). In recent years, the overriding source of funding for control measures was from the Working for Water programme within the Department of Environmental Aff airs (Box 6.2). This public works programme has spent ZAR 12 billion (unadjusted for infl ation) on invasive plant control projects between 1995 and 2012. However, this amount has only been enough for control teams to reach somewhere between 2% and 5% of the estimated extent of the most important invasive species, and consequently invasions continue to spread (Van Wilgen et al., 2012; Henderson & Wilson, 2017). Nonetheless, the fact that the Working for Water (WfW) programme exists, and is well-funded, is remarkable, especially for a developing country. There are signifi cant opportunities for improvements to WfW (Box 6.2), some of these are summarised in the points below. This assessment has highlighted that the biological control of invasive plants has been notably successful. The South African government, through the WfW programme, has continued to fund biological control research and implementation, with very encouraging results. Of the 60 invasive plant species or taxa targeted for biological control thus far in South Africa, 15 species are now under complete control, with a further 19 species under a substantial degree of control (Zachariades et al., 2017). By combining biological and mechanical and chemical control, it has been possible to eff ectively reduce the populations of some of the most damaging invasive species, as appears to have been the case for Hakea and Acacia species in the Western Cape (Esler et al., 2010; Moran & Hoff mann, 2012), and for Lantana and Opuntia species in the Kruger National Park (Van Wilgen et al., 2017). The economic benefi ts of these interventions have been substantial, with estimated cost to benefi t ratios indicating that, for every one ZAR invested into biological control, economic losses due to invasive alien plant invasions of between ZAR 8 and over ZAR 3000 have been avoided. A few eradication projects have been successful, and more are likely to follow in the near future. The number of species targeted for eradication is increasing, with several other assessments of eradication feasibility underway. 117 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES Several studies have also shown that control interventions have succeeded in reducing the extent of invasions in some areas. An early example of this was provided by Macdonald, Clark & Taylor (1989), who demonstrated that a properly planned and executed approach was able to substantially reduce populations of invasive alien trees and shrubs in the Table Mountain National Park. Concerted eff orts to remove invasive pine trees (and other species) from fynbos ecosystems have resulted in marked declines in the density of these species in the Berg River Catchment (funded by WfW; Fill et al. 2017), and on the Vergelegen Estate (privately funded; (Van Rensburg, Richardson & Van Wilgen 2017). McConnachie et al. (2016) were similarly able to demonstrate that the invaded area in the Hawequas Mountains would have been almost 50% higher if there had been no control intervention. In savanna ecosystems, ongoing control has reduced the degree of invasion by a number of species (including Opuntia stricta, Australian pest pear, and Lantana camara, lantana, in the Kruger National Park (Van Wilgen et al., 2017) and Chromolaena odorata, triffi d weed, in the Hluhluwe-iMfolozi Park (Dew et al. 2017; Te Beest et al. 2017). Thus, at a local scale, some control measures have demonstrably been eff ective. However, despite the expenditure of at least ZAR 12 billion (over 20 years, unadjusted for infl ation), and the localised successes outlined above, plant invasions have nonetheless generally continued to grow, some substantially (see Henderson & Wilson, 2017; and the discussion in Chapter 4). One of biggest problems impacting on the eff ectiveness of alien plant control measures in South Africa is the lack of adequate goal-setting and planning, accompanied by the monitoring of inputs rather than outcomes. A lack of clear strategic planning and goal-setting arguably leads to too many projects that are ineff ective, rather than having fewer but more eff ective projects in agreed priority areas. Successive reviews of the Working for Water programme (in 1997, 2003, 2012 and 2014) have explicitly raised the concern of a lack of strategic planning (see Van Wilgen & Wannenburgh, 2016, for a review). Most alien plant control projects in South Africa have been given goals for the amounts to be spent, the number of people to be employed, and the areas to be treated. Monitoring of progress has a focus on these goals, and there are typically no goals that describe desired outcomes in terms of reducing plant invasions to manageable levels, what those manageable levels would be, and how long it would take to achieve them. In the absence of monitoring programmes that are focussed on these ecological outcomes, it is not possible to objectively assess management eff ectiveness. The absence of adequate planning and monitoring could be attributed to the requirement to minimise the costs per person-day (and thus maximise the number of people employed), which is a key target on which continued funding depends. This reduces the programme’s ability to adequately invest in planning and monitoring, which would be relatively expensive and would increase the overall costs per person-day. The existence of dual goals (ecological restoration and the creation of employment) is a double-edged sword. On the one hand, it is absolutely essential for the retention of the political support that ensures funding, but on the other it restricts the ability to focus funds where they are most needed for ecosystem restoration purposes. The achievement of employment and spending targets are relatively easy to understand, as is the target to treat a particular area. The target of an area to treat is not useful, however, as it provides no guidance on the purpose of treatment (for example to prevent erosion of, or to restore, vital ecological services), nor does it require the quality or eff ectiveness of the treatment to be recorded. The formulation of meaningful targets for ecosystem restoration, and a formal requirement to meet them, could alleviate this problem, but given the current set of measures it is all too easy for managers to meet their targets by simply creating employment and working anywhere to any standard. 118 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 Several studies have shown that the actual costs of alien plant control operations (be they publically or privately funded) are much larger than the estimated costs. Actual costs should be 100% of the estimated costs, but in a range of studies they were found to be 150–860% (McConnachie et al., 2012); 300–500% (McConnachie et al., 2016); 360% (Van Rensburg, Richardson & Van Wilgen 2017); and 720% (Van Wilgen et al., 1997; Fill et al., 2017, with the project still ongoing). These fi ndings point to the complexity of eff ectively managing invasive plants, and the eff ort needed to address the issue, as well as to ineffi ciencies in the implementation of management. Eff ective control of invasive species would require adherence to best practice methods where these are available. This has not always been the case, and has led to ineffi ciencies. For example, Macdonald, Clark & Taylor (1989) noted that the practice of linking alien plant clearing projects to the supply of fi rewood led to substantial ineffi ciencies. Fill et al. (2017) found that alien plant clearing operations in the Berg River catchment, Western Cape, failed to make adequate use of power tools, did not make any use of prescribed burning, and ran uncoordinated, separate projects to control plants in accessible and inaccessible areas, resulting in ineffi ciencies. The frequent failure to integrate biological control with mechanical and chemical control in many cases was outlined by Zachariades et al. (2017), with, in one case, millions of rands spent mechanically clearing Cereus jamacaru, a cactus species that is under complete biological control (Van Wilgen et al. 2012a). McConnachie etal. (2016) also noted that control success in the Hawequas Mountains would have prevented a larger area from being invaded if it had focussed all of its clearing eff ort on scattered plants in untransformed land, rather than on dense invasions and abandoned plantations. Some of these issues could be addressed by aligning plans with best practice, but others would require improved training of workers to higher levels of competency. For example, both the use of power tools and the setting of prescribed burns can be risky, and are currently avoided due to concerns for the safety of inadequately-trained workers and others. The employment model currently used by public works programs can lead to substantial ineffi ciencies. The practice of issuing short-term contracts for clearing and follow-up (instituted as a developmental opportunity for disadvantaged contractors) requires cumbersome procedures to approve and implement, and results in delays to work schedules and late payments to intended benefi ciaries, substantially diluting the intended social benefi ts (Ashton, 2012; Coetzer & Louw, 2012; Hough & Prozesky, 2012). It would arguably be better to employ fewer, better-trained, better-equipped personnel on a more permanent basis. The current model also does not allow for capacity to be built within the conservation authorities who are ultimately mandated to manage protected areas, and a scenario in which this funding is phased out, or channelled elsewhere, would leave the conservation agencies without embedded capacity and experience to manage invasions. However, other employment models are used. For example, Working on Fire, another in the suite of public works programs, requires benefi ciaries that meet fi tness standards, provides training to ensure adherence to work standards, and employs people on an annual contract basis, where they receive a regular, dependable wage. Overall, there is a general concern among many stakeholders regarding the effi ciency of government-sponsored alien plant control projects, but this is diffi cult to substantiate due to the scarcity of documented evidence. The fi ndings of McConnachie et al. (2012), and Kraaij et al. (2017) that point to ineffi ciencies in the application of treatments, including non-treatment of areas, provides some evidence. Shackleton et al. (2016), in a survey of perceptions of managers, landowners, offi cials and academics, found that most landowners (>80%) regarded 125 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES The input indicator values for money spent are given in Table 6.5 across all activities (pathways, species and areas). The other indicator values for control eff ectiveness for area management are given in Table 6.10. TABLE 6.10 Indicators for control eff ectiveness of areas INDICATOR VALUE BASIC ADVANCED LEVEL OF CONFIDENCE NOTES 15. Planning coverage (input) 15.1. Areas that have management plans in place. 4% of areas have plans 15.2. Areas that have management plans in place, with assessment of quality of management plans 2% of plans are adequate 42% are partially adequate 56% are inadequate 15.3. As for 15.2, with priority rankings No data 15.1. Medium 15.2. Medium 15.3. N/A Based only on plans submitted in terms of the alien and invasive species regulations, but the absence of adequate plans is a welldocumented phenomenon. 18. Area treated (output) 18.1. Proportion of area that needs to be managed and is being managed. 0.36% 18.2. As for 18.1, with interventions assessed for adequacy. No data 18.1. Low 18.2. N/A 18.1. is based on the area of untransformed land in South Africa (973643 km2), assuming that 8% (Versfeld, Le Maitre & Chapman, 1998) (i.e. 77900 km2) is invaded and needs to be managed. The area that has been treated (282 km2) includes all land parcels that have been worked on by public works alien plant control teams over 20 years. 21. Eff ectiveness of area treatments (outcome) 21.1. Proportion of areas in control eff ectiveness categories AND an assessment of any negative impacts of control Not known: 99.6% Counterproductive: 0% None/Ineff ective: 0.1% Partially eff ective: 0.2% Eff ective: 0.1% Permanent: 0% An assessment of the negative impacts of control has not been made. 21.2. Quantitative measure of control on Relative invasive abundance or Invasive species richness AND a formal environmental and social assessment of non-target eff ects of the interventions No data 21.3. Return on investment expressed as a ratio of the amount spent on control to the value of avoided cost of impact. AND non-target impacts as costs Benefi t:cost ratios between 0.03 and 0.75 Non-target impacts not assessed 21.1. Low 21.2. N/A 21.3. Low For 21.1., it was assumed that 77900 km2 is invaded and needs to be managed, and that 282km2 is known to be being managed (see above). Proportion in eff ectiveness categories based on 12 available studies (section 6.4.2) where the outcomes of management were documented (8% were eff ective, 58% were partially eff ective, and 34% were ineff ective). Benefi t:cost ratios are from a single study involving six projects (Hosking & Du Preez, 2004) 126 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 6.6.5. Estimation of high-level indicators for overall management eff ectiveness High-level indicators are provided in Table 6.11 (see Table 6.12 for the calculation). The high-level indicator for the Rate of introduction of new unregulated species was estimated based on the average for the decade 2000–2009 (see Figure 3.8). The Number of species that have major impacts was the sum of species considered by experts to have either major or severe impacts (Table 4.7). However, as explained earlier, there have been almost no formal assessments of species impacts, and thus the indicator should not be used as a basis for estimating trends in future. A formal re-assessment of all alien species using the EICAT and SEICAT methods every three years is required. Obtaining an accurate estimate of the Area experiencing major impacts would be dependent on: (1) a formal assessment of the impact of individual species, and (2) a reliable estimate of the distribution of those species. Currently, both components do not exist. The estimate of 1.4% is simply illustrative. It assumes that the area estimated to be densely covered by alien plants will experience major impacts, and is based on a mapping exercise that is both crude and 20 years out of date (Le Maitre, Versfeld & Chapman 2000). The indicator for overall Level of success in managing invasions (Table 6.11) is calculated as the mean of estimates of level of success for pathways, species and areas. Each was obtained by multiplying the proportion that are treated (from indicators 16.1, 17.1 and 18.1 for pathways, species and areas respectively) by the weighted outcome indicators (indicators 19.1, 20.1 and 21.1) as described for high-level indicator D in Appendix 1. See Table 6.12 for the values at each step of the calculation. TABLE 6.11 High-level indicators of the status of biological invasions and their management in South Africa in 2017. HIGH-LEVEL INDICATOR VALUE LEVEL OF CONFIDENCE NOTES A. Rate of introduction of new unregulated species 7 species per year Low Based on the average for the decade 2000–2009 (see Figure 3.8) B. Number of species with major impacts 107 species Not applicable Based entirely on expert opinion, and so does not represent an appropriate base-line. For future reports, formal assessments of impact will need to be conducted (see Table 4.7) C. Percent of area experiencing major impacts 1.4% Low Based on the only available estimate of dense (“condensed”) cover of invasive alien plants in South Africa (1.7 million ha, (Le Maitre, Versfeld & Chapman, 2000)) D. Level of success in managing invasions 5.5% Low Average of pathway success (15.8%), species success (0.65%) and area success (0.0005%) The returns on investment from selected biological control projects aimed at invasive alien plants are between 8:1 & 3726:1 THE SITUATION 127 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES TABLE 6.12 Values used to calculate the high-level indicator D. Level of success in managing invasions. The proportion managed is based on the output indicators: 16. Pathways treated, 17. Species treated and 18. Areas treated. The proportion with partially eff ective/eff ective or permanent management is based on the outcome indicators: 19. Eff ectiveness of pathway treatments, 20. Eff ectiveness of species treatments and 21. Eff ectiveness of area treatments. The management eff ectiveness score is calculated by determining the sum of the weighted proportion with partially eff ective management (multiplied by 0.2) and the weighted proportion with eff ective management (multiplied by 1). The level of success is the product of the proportion managed and the management eff ectiveness score. PROPORTION MANAGED PROPORTION WITH PARTIALLY EFFECTIVE MANAGEMENT PROPORTION WITH EFFECTIVE OR PERMANENT MANAGEMENT MANAGEMENT EFFECTIVENESS SCORE LEVEL OF SUCCESS (PROPORTION) Pathways 0.773 0 0.205 0.205 0.158465 Species 0.243 0.049 0.017 0.027 0.0065124 Areas 0.004 0.002 0.001 0.001 0.00000504 BOX 6.1 THE POTENTIAL ECONOMIC BENEFITS OF EFFECTIVE CONTROL MEASURES Estimates of the monetary value of impacts generated by invasive species in South Africa indicate substantial negative eff ects in economic terms. For example, one study estimated that, at levels of infestation in 2010, invasive alien plants caused economic losses amounting to over ZAR 6 500 million every year, mostly for losses of water runoff , but also for loss of livestock production from invaded rangelands, and income from biodiversity-related goods and services. Three points should be noted with regard to these estimates: • Because of the lack of accurate data, it was necessary to make a number of assumptions when making these estimates. The estimates are therefore crude, but are large enough to indicate that the real economic impacts could be substantial. • The estimates only include water runoff , production of livestock from rangelands, and limited biodiversity goods and services. There are many other impacts associated with invasive species that were not included because of a lack of data. These estimates are therefore conservative, and will almost certainly be greater. • The impacts will grow as invasive species continue to spread, and as additional species become invasive. Given the large and growing impacts of invasive species, attempts to contain or reduce these impacts would be economically justifi able if the control measures were eff ective and effi cient. The best available evidence for this comes from the fi eld of biological control. By comparing the costs of biological control research and implementation to the benefi ts of restored ecosystem services, or avoided costs, and avoided ongoing control costs, biological control has been shown to be extremely benefi cial in economic terms: estimated benefi t: cost ratios ranged from 8:1 up to 3726:1. This essentially means that for every one rand invested into control, losses of between ZAR 8–3700 were prevented. Key references: Le Maitre et al. (2011); Van Wilgen & De Lange (2011a). 128 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 BOX 6.2 THE WORKING FOR WATER PROGRAMME: ACHIEVEMENTS AND CHALLENGES The Working for Water Programme (WfW) is South Africa’s largest funder of invasive species control measures. Established within the Department of Water Aff airs in 1995 with an initial annual budget of ZAR 25 million, its original purpose was to implement invasive plant control operations to reduce their impacts on water resources, and to create much-needed employment amongst the rural poor. It has subsequently been moved to the Department of Environmental Aff airs, where it remains the largest of a suite of programmes in the Department’s Natural Resource Management Programmes. Currently, it has an annual budget of ZAR 1.5 billion, and employs 39500 people in 358 clearing projects across the country. WfW has achieved a great deal. The fact that a programme of this size exists at all, especially in a developing country, is a remarkable achievement, and it bears testimony to the hard work of those responsible for its establishment and growth. The programme has secured ZAR 10 billion (unadjusted for infl ation) for invasive species management over the past 20 years, and has provided conservation agencies, water and irrigation boards, municipalities and private landowners with funding for the management of invasive alien plants, that they would otherwise not have had. However, the programme faces signifi cant challenges. Despite the generous budget, it is patently inadequate to achieve eff ective control everywhere, and it is forced to make choices about where, and on which species, to spend money. The vital political support that is needed to sustain this programme arises from its demonstrated ability to create employment, but this can be a double-edged sword as the employment goal is often given higher priority than the goal of achieving ecological restoration (and all of the benefi ts that go with ecological restoration). The need to maximise employment also reduces the programme’s ability to invest adequately in planning and monitoring, which would be expensive and would increase the overall costs per person-day. Minimising the costs per person-day (and thus maximising the number of people employed) is a key target on which continued funding depends. Consequently, the programme’s achievements are arguably far less than they could have been under diff erent operating rules. Key reference: Van Wilgen & Wannenburgh (2016). 129 CHAPTER 6 I THE EFFECTIVENESS OF CONTROL MEASURES BOX 6.3 THE POTENTIAL CONTRIBUTION OF BIOMASS UTILISATION TO THE EFFECTIVE CONTROL OF INVASIVE SPECIES. Photographer: B. van Wilgen Example of a prototype low-cost housing unit that utilises chip-board manufactured from invasive alien plant biomass. Given that the clearing of invasive species (especially woody species) can generate a large amount of potentially useful biomass, it seems logical that the opportunity should be taken to make use of this biomass. Currently, South Africa’s National Strategy on Biological Invasions calls for clear recommendations to be made on this approach based on “an assessment of the feasibility, viability and eff ectiveness of projects aimed at producing energy [and other products] from plant biomass”. Such an assessment has not yet been carried out. South Africa has nevertheless already established several factories that manufacture furniture from alien plant wood, and is seriously investigating the potential to mass-produce low-cost housing from alien plant biomass. Despite the apparent substantial potential for biomass utilisation to contribute to invasive plant control eff orts, it would be prudent to investigate this thoroughly before making any decision to implement utilisation on a large scale. A number of points need to be explicitly considered: • Developing the infrastructure to process biomass could create a large dependency on a resource that is targeted for reduction to very low levels. This would be problematic as it could create a substantial confl ict in future. • Utilisation does not necessarily contribute to eff ective control. Utilisation targets usable biomass, and does not address smaller trees, regeneration or re-sprouting, or seed banks. Site disturbance and transport could also actually exacerbate rather than reduce the problem. • Utilisation may only be economically feasible in certain areas, but not in remote or inaccessible sites, or in cases where there are scattered populations that should receive priority as targets for clearing. • Utilisation projects can, and often have, generated unintended consequences, including using infrastructure to process non-target or indigenous species, or encourage spreading of the target invasive species by people who want to benefi t from utilisation projects where the species does not yet occur. Three studies of the potential eff ectiveness of utilisation have been carried out in South Africa to date. Mugido et al. (2014) investigated the feasibility of using harvested invasive plant biomass in the Port Elizabeth area. The study showed that the project proved to be “fi nancially viable”, but only when the energy entrepreneur obtained biomass generated by government-funded clearing projects at no cost, and then only under specifi c conditions. The potential use of Acacia cyclops from the De Hoop Nature Reserve (Western Cape) to generate electricity was investigated by Mudavanhu, Blignaut & Nkambule 2016. They concluded that this would be favourable when compared to electricity generation using diesel generators. Finally, Vundla et al. (2016) estimated the contribution of value-added products to the viability of woody plant control projects in the Kouga, Krom and Baviaans catchments (Eastern Cape). They concluded that value addition would increase the returns on investment from these projects. All of these studies are predictions, based on assumptions, including that control operations will be eff ective and effi cient, and will be completed within budget. More studies are needed to establish whether this is the case. Key references: Mugido et al. (2014); Vundla et al. (2016); Mudavanhu, Blignaut & Nkambule (2016) . 7 EFFECTIVENESS OF REGULATIONS Lead authors: Tsungai Zengeya, Brian van Wilgen, John Wilson Contributing authors: Tumelo Morapi, Happiness Mnikathi, Tendamudzimu Munyai, Karabo Malakalaka, Stiaan Kotzé, Khathutshelo Nelukalo, Oupa Chauke, Bernard Ndou Chapter summary This chapter reports on the current regulatory framework in South Africa for dealing with biological invasions, and specifi cally the eff ectiveness of the Alien and Invasive Species Regulations (A&IS Regulations) under the National Environmental Management: Biodiversity Act (NEM:BA). Eff ectiveness is discussed here in terms of managing pathways of introduction and dispersal, individual species and specifi c areas, as well as on other aspects that are required to be reported on under the A&IS Regulations (e.g. state-funded research). South Africa is one of the few countries that has comprehensive regulations in place to manage biological invasions, and many parts of the regulations are innovative. The regulations deal with most aspects of biological invasions (pathways, species, and areas) and most mechanisms to implement, update, review, and appeal the regulations are clear, and as such were rated as “substantial”. However, although there are some sections of the legislation that are relevant to the management of some specifi c pathways (e.g. the intentional import of alien species for the pet trade), the NEM:BA A&IS Regulations do not specifi cally regulate pathways. In addition, there are several factors, such as the lack of a national strategy to manage biological invasions, as well as organisational and human capacity constraints, that limit the implementation of the regulations. The evidence base for listing species was not presented in a standard, transparent manner prior to the promulgation of the regulations, although some species have subsequently been assessed. While these assessments are consistent with the regulations, they do not meet international best practice for risk analyses. A risk analysis framework has been developed but is still to be implemented. Applications were made for the import of 6 unlisted species and on the basis of risk assessments for these species, 21 import permits were issued for fi ve species. A total of 647 permits were issued for restricted activities involving 50 listed alien taxa, including permits for multiple species that are listed in various categories. Permits were for restricted activities related to the trade (44%), conveyance (26%), possession (21%), and import (8%) of alien species, as well as for research (2%) on these species. For listed invasive alien plants, notices have been served to the owners of 85 properties across South Africa (59 to private landowners and 26 to plant traders), with an overall compliance of 95%. For listed invasive alien animals, notices have been served to the owners of 119 properties (78 to pet shops, 19 to game farms, 12 to private holdings and 10 to sanctuaries or zoological gardens) with an overall compliance of 82%). CHAPTER 7 I EFFECTIVENESS OF REGULATIONS CHAPTER 7 I EFFECTIVENESS OF REGULATIONS Species management programmes (as catered for in the A&IS Regulations) have only been developed for Parthenium hysterophorus (parthenium) and Campuloclinium macrocephalum (pompom weed), as well as for the genera Acacia (Australian wattles) and Prosopis (mesquite) and the family Cactaceae. None have yet been formally implemented, so their potential eff ectiveness cannot yet be assessed. Landowners are required to notify government of the listed invasive species on their land, but only 59 notifi cations were received, constituting less than 0.001% of the total number of land parcels in the country. Although required, it is not possible to assess whether, or to what degree, the sellers of immovable property have notifi ed the purchaser of that property of the presence of listed invasive species on that property, as there is no legal requirement for any person other than the purchaser to be notifi ed. Only 29 area management plans (termed “Invasive Species Monitoring, Control and Eradication Plans” in the regulations), covering about 4% of the land-surface of the country, were submitted to the Department of Environmental Aff airs (DEA) and the South African National Biodiversity Institute (SANBI). Only one of these plans was of adequate quality when assessed against the guidelines for the preparation of such plans. Therefore, a lack of adequate planning remains an obstacle to the control of biological invasions in specifi c areas. Organisations that conduct state-funded research on invasive species must lodge research proposals and fi ndings with SANBI. As of March 2017, no such proposals or fi ndings had been lodged with SANBI, despite a substantial amount of research being funded by the state. A person who fails to comply with the provisions of the A&IS Regulations would be liable, on conviction, to a fi ne or imprisonment, or both. To date, no cases have been brought to trial. The regulations have been in place for less than three years, and it is probably premature to expect that their eff ectiveness could be assessed at this early stage. However, a number of important points emerge, including: high levels of non-compliance with some regulations; a shortage of capacity within the DEA to ensure compliance (although the magnitude of the shortage has not been assessed); the apparent absence of a strategic approach to implement the regulations in a capacity-constrained environment; and contestation of the desirability of regulations for particular species. Finally, where there has been activity and data are available for this report, the data only focussed on outputs (e.g. number of permits issued). Linking these data to outcomes in terms of the state of biological invasions in South Africa will require the development of agreed methodologies. Limonium sinuatum (statice) – Sofi a Turner 132 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 7.1 INTRODUCTION In 2014 the government published the Alien and Invasive Species Regulations (A&IS Regulations) in terms of the National Environmental Management: Biodiversity Act (NEM:BA, Act 10 of 2004). These regulations specify the way in which alien species are to be managed. In addition, the regulations prescribe the process to be followed if a new alien species is to be imported into the country, and they also list species that are prohibited from importation. The intent of the regulations is to reduce the risk of importing alien species that could become invasive and harmful, reduce the number of alien species becoming invasive, limit the extent of invasions, and reduce the impacts caused by these invasions. This is to be achieved, in particular, by assigning responsibilities for the control of listed invasive species, and where appropriate to prescribe the conditions under which species that are both invasive and benefi cial can be owned, cultivated, transported and traded, as well as assign the responsibility to owners to prevent the spread of such species. The regulations also require that research proposals, and research fi ndings should be submitted to the South African National Biodiversity Institute (SANBI). This includes any “research and biological control relating to any aspect of the invasiveness or potential invasiveness of an alien species or a listed invasive species or the prevention, eradication or control of such invasive or potentially invasive species” that is wholly or partly funded by the state, or conducted in terms of a permit to carry out research on a listed invasive species. The regulations further require SANBI to report, within three years of the promulgation of the regulations and every three years thereafter, on the eff ectiveness of the regulations, based inter alia on notifi cations from land owners, permits issued, cancelled or refused, and management plans submitted (see Table 7.1 for details). This chapter considers the eff ectiveness of the NEM:BA A&IS Regulations in terms of managing pathways of introduction and within-country dispersal, individual species and specifi c areas, and assessing alien species-related research. There are also several additional Acts in South Africa that are relevant to the management of biological invasions. The most important of these (Box 7.1) are under the jurisdiction of the Department of Agriculture, Forestry and Fisheries (DAFF), and are not covered in this report. TABLE 7.1. Aspects of the National Environmental Management: Biodiversity Act (NEM:BA) and the Alien and Invasive Species (A&IS) Regulations relevant to the management of species, areas and research. CATEGORY ASPECT THAT REQUIRES REGULATION RELEVANT SECTION OF THE A&IS REGULATIONS (AND OF NEM:BA AS SPECIFIED) Regulations relevant to managing individual invasive species Permits issued for the import of new species that previously were not in South Africa Section 17 Permits issued for taxa in Category 2 and other categories that are already in the country; permits refused or cancelled Section 9.1 (a); Section 12(1); Section 21 (2) (b) Invasive Species Management Programmes Section 9(1) I Emergency interventions and enforcement actions involving listed invasive species issued by the Minister. Section 11 (2) (b) (iv) Prosecution of off enders Section 35 Regulations relevant to managing specifi c areas Notifi cations received from owners of land regarding the listed invasive species occurring on their land Section 11(2)(b)(i) of the regulations, with reference to Section 73(2)(a) of the NEM:BA Act Notifi cations and directives issued to landowners Section 13(1)(a); Section 31 Level of compliance with property transfer notifi cations Section 29 (3) Invasive Species Monitoring, Control and Eradication Plans (i.e. area management plans) received from organs of state and management authorities of protected areas Section 8 (2) (b); Section 9(1)(b) Invasive species status reports for protected areas, submitted since 2004 Section 77 (1) and (2) of NEM:BA Prosecution of off enders Section 35 Regulations relevant to research on biological invasions Research proposals, and biological control proposals, submitted Section 10 (1) Research reports or publications submitted Section 10(4) 133 CHAPTER 7 I EFFECTIVENESS OF REGULATIONS BOX 7.1 ADDITIONAL LEGISLATION IN SOUTH AFRICA THAT IS RELEVANT TO THE REGULATION AND MANAGEMENT OF BIOLOGICAL INVASIONS THOUGH NOT SPECIFICALLY DEALT WITH IN THIS REPORT There are several Acts in South Africa, in addition to the National Environmental Management: Biodiversity Act, that are relevant to the management of biological invasions. This box lists examples of these acts, along with the relevant reporting requirements. ACT ADMINISTERED BY REPORTING REQUIREMENTS Agricultural Pests Act, 1983 (Act No. 36 of 1983) Department of Agriculture, Forestry and Fisheries • Compulsory notifi cations of certain pests from land users • Control measures prescribed for diff erent taxa, or in respect of diff erent areas, diff erent circumstances, or in other respects as the Minister may think fi t • Permits that have been issued for controlled goods showing the reason for the permit • Off enses and successful prosecutions Animal Diseases Act, 1984 (Act No. 35 of 1984) Department of Agriculture, Forestry and Fisheries • Permits for imported controlled animals or other items • Control measures for controlled animals or other items • Reports of controlled animal disease • Off enses and successful prosecutions Animal Health Act, 2002 (Act No. 7 of 2002) Department of Agriculture, Forestry and Fisheries • Reports of controlled animal disease • Permits and health certifi cates for animals, parasites, contaminated or infectious items that have been imported into the country • Off enses and successful prosecutions National Environmental Management: Protected Areas Act (Act 57 of 2003) The Department of Environmental Aff airs • Register of alien species in protected areas • Performance monitoring indicators • Off enses and successful prosecutions Conservation of Agricultural Resources Act (Act 43 of 1983) Department of Agriculture, Forestry and Fisheries • Declared weed and invader list • Weed control schemes and progress reports • Weeds on any seed, grain, hay or other agricultural product • Weeds on any animal which is driven on a public road, conveyed in a vehicle or off ered for sale at a livestock auction • Orders issued for weed destruction, removal or return of the above-mentioned weeds. • Control plans for invaders and weeds • Directives for complying with control measures 134 THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 7.2. THE STATE OF THE CURRENT REGULATORY FRAMEWORK The status of the current regulatory framework was assessed using the indicator Quality of regulatory framework (see Appendix 1 for more details). The indicator is an input indicator that helps to address three questions: 1) what regulatory framework is in place to manage biological invasions; 2) what is its level of completeness (does it cover all aspects of pathways, species, and areas); and 3) what mechanisms are in place to enable its implementation, update, review, and appeal? At a basic level the indicator is meant to provide a country-level assessment of the degree to which authorities are able to regulate the utilisation, movement, and trade of alien species and citizens are able to take steps to control problematic invasive species. At a more advanced level, the indicator can be used to assess the quality of the regulatory framework at lower administrative entities (e.g. provinces), and also to assess the level of inter-agency co-operation. The quality of the regulations is evaluated as either: none, partial, substantial or complete based on their completeness and the presence of enabling mechanisms for implementation, update, review, and appeal. In this report the NEM:BA A&IS regulations (2014) were assessed as “substantial” because they deal with most aspects of biological invasions and most mechanisms for implementation, update, review, and appeal are clear. However, pathway specifi c actions are partly addressed and there are several factors such as the lack of a national strategy to manage biological invasions, organisational and human capacity constraints that may limit the implementation of the regulations (Table 7.2). TABLE 7.2 A breakdown of coverage of the National Environmental Management: Biodiversity Act’s Alien and Invasive Species Regulations (2014) across all aspects of biological invasions. This is with reference to indicator 13. Quality of regulatory framework. ASPECT OF REGULATIONS ASPECT OF BIOLOGICAL INVASIONS PATHWAYS (incl. subcategories) SPECIES (incl. all taxa) AREAS (incl. diff erent spatial scales and ownership) Is there a mandate for management interventions? Partial Substantial Substantial Is there provision for enforcement of non-compliance? Partial Substantial Substantial Is there a requirement for regular assessment of performance, and review? Partial Substantial Substantial 7.2.1. What is required to improve the eff ectiveness of the regulations? Need for pathway-specifi c management measures. The NEM:BA A&IS Regulations do not specifi cally regulate pathways but several sections or aspects of the regulations are relevant to the management of some pathways. For example, the regulations require permits for the import of new species. However, these measures are actually species-specifi c measures and not pathway management actions. There is therefore a need for the regulations to have pathway specifi c-management measures, for example the proposed Ballast Water Act that is specifi cally meant to prevent the transfer of alien and invasive species into South African waters through the release of ballast water by ships. Which alien species should be regulated? Currently, the NEM:BA A&IS regulations list 556 taxa as invasive. However, not all of these species are necessarily harmful to the extent that would justify the expenditure of time and eff ort on their management, given that capacity to manage and to regulate is limited. Regulations should therefore arguably focus APPENDIX 1 – INDICATOR FACTSHEETS 237 Limits to usefulness and accuracy This indicator requires detailed mapping. It is thus most likely to be used at smaller spatial scales. It will nevertheless be useful for assessing the levels of invasion in particular types of areas, for example protected areas. It requires information on indigenous abundances as well, and when dealing with coverage data, the total coverage might either be much greater than 100% (i.e. overlapping canopies), or less than 100% (i.e. bare rock). The impact of diff erent levels of relative abundance will also vary. So an understory shrub at 50% coverage might have much lower impacts than a vine that overtops and smothers vegetation which is also at 50% coverage. Updating the indicator This indicator would be assessed at the scale for which management plans are available, and where goals are set to achieve reductions in the relative abundance of alien species. Monitoring and updating of the database on which this indicator is based should be continuous, as management is ongoing, likely as part of annual planning updates. In South Africa it is proposed to update indicators every three years. Closely related indicators DEPENDS UPON LINKS WITH REQUIRED FOR 5. Number and status of alien species 6. Extent of alien species 7. Abundance of alien species None 8. Impact of alien species 12. Impact of invasions 15. Planning coverage 19. Eff ectiveness of pathway treatments 20. Eff ectiveness of species treatments 21. Eff ectiveness of area treatments B. Number of invasive species that have major impacts C. Extent of area that suff ers major impacts from invasions D. Level of success in managing invasions Additional information and comments The data can be linked to other GIS layers to look at possible interactions, e.g. with human footprint. Rather than broad taxonomic groups, it can be important to consider functional groups, or function itself, e.g. what proportion of photosynthesis in a given region is due to alien species (and how has this changed post-invasion). THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 238 12 IMPACT OF INVASIONS Use and interpretation This indicator assesses the combined impact of all invasive species within a particular area on the delivery of selected ecosystem services, or on biodiversity. It should have a focus on those ecosystem services that are important in the context of the area concerned (for example on water resources in dry regions, livestock production in rangelands, or biodiversity in protected areas) and can be used to prioritise areas for management interventions. At a more advanced level, the value of impacts can be expressed in monetary terms and so used for calculations of costs and benefi ts of control. Potential for aggregation Impacts on ecosystem services that are made at fi ner scales can be aggregated upwards at larger scales. Possible reasons for upward or downward trends Increases in impact (decreases in ecosystem service delivery) can be associated with the physiological or competitive consequences of invasions. For example, displacement of plants that are able to conserve water with species that are less effi cient water users can reduce streamfl ow and deplete groundwater resources; and unpalatable or thicket-forming species can displace palatable grass species in rangelands, reducing the livestock carrying capacity. Upward trends can also be the result of increases in the spread of alien species; shifts in which alien species are invasive towards more damaging species; or due to the accrual of impact over time, as even if extent or abundance of invasions do not change over time, biophysical thresholds can be crossed leading to ecosystem level impacts (Suding & Hobbs, 2009). Implications for biodiversity management of change in the indicator The size and value of impacts would be important factors to consider when allocating scarce management resources to address and hopefully reduce, or slow the growth of, harmful impacts. Management resources should be directed to those areas where attractive returns on management interventions could be realised (potentially, but not necessarily) including areas where the impacts are greatest. Units in which it is expressed (from basic to advanced) 12.1 Factor with fi ve levels of impact: • Not known • Minor • Moderate • Major • Massive 12.2 The reduction caused by the invasions expressed quantitatively in the units in which the ecosystem service is measured (for example, water yield expressed in m3 per ha, and rangeland carrying capacity in livestock units per ha). 12.3 Net present monetary values of the reduction in the relevant ecosystem service or biodiversity indicators. APPENDIX 1 – INDICATOR FACTSHEETS 239 Description of source data The use of this indicator requires data on the spatial distribution and magnitude of ecosystem services, and on the impact of invasions on that service. While the magnitude of a wide range of ecosystem services can be assessed, good information on the impacts of invasions on those services are scarce, as relatively few studies have been conducted. Calculation procedure 12.1 Ecosystem services should be mapped at appropriate scales, and this is more easily achieved for some services (for example water or timber extraction, or livestock or fi sh production) than for others (for example aesthetic or cultural values). The impact of invasions on these services should be modelled based on research results where they are available, and extrapolated. • Not known: there has been no estimate of whether there has been a reduction in the relevant ecosystem service or biodiversity indicators attributable to the invasions. • Minor: there has been a < 2% reduction in the relevant ecosystem service or biodiversity indicators attributable to invasions. • Moderate: 2–10% reduction. • Major: 10–50% reduction. • Massive: > 50% reduction. 12.2 As for 12.1 but where the data are of suffi cient resolution and models of suffi cient reliability that a quantitative percentage can be obtained. 12.3 Conversion of ecosystem services to monetary values would require further research in which the value of sustainable yields (of water, livestock, or harvested products) would have to be estimated for the scale concerned. Guide for applying confi dence levels 12.1 HIGH Based on well-documented impacts of particular alien species combined with quantitative information on relative invasive species abundance with a medium or high level of confi dence (see 11.2) MEDIUM Based on well-documented impacts of particular alien species combined with qualitative information on Relative invasive abundance (see 11.1) LOW Based on expert opinion 12.2 HIGH Based on levels of ecosystem services that have been measured and quantifi ed across the region; and on robust studies that quantify the impact of invasions on these services MEDIUM Based on levels of ecosystem services that have been measured for representative parts of the region, with well-tested spatial models used to extrapolate to the whole region. LOW Based on estimates of ecosystem services derived from spatial modelling, and/or on modelled estimates of the impact of alien species on these services. 12.3 HIGH Based on direct valuation of measured and quantifi ed ecosystem goods and services in the area concerned. MEDIUM Based on indirect estimations of the market value of modelled levels of ecosystem services (for example, by comparison to values for similar services estimated elsewhere). LOW Based on market values of ecosystem services derived from expert opinion. Most eff ective forms of presentation 12.1 Spatially (on maps) or graphically by means of bar graphs showing trends over time or under diff erent scenarios of invasion. 12.2 As for 12.1 12.3 Tables THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 240 A B Biodiversity intactness % Fynbos Grassland Succulent karoo Nama karoo Savanna and thicket 0 10 20 30 40 50 60 70 80 90 100 Without alien plants With current levels of infestation With future levels of infestation FIGURE A1.10 (Indicator 12.2) Estimates of the Impact of invasions on water resources in South Africa. In panel a) are estimates of the reductions in mean annual runoff (MAR) due to invasive alien plants in the quaternary catchments of South Africa. The quaternary catchments where data were not available to estimate impact are shown in grey; in panel b) are estimates of the current and potential impacts of invasive alien plants on surface water runoff in fi ve terrestrial biomes in South Africa (Le Maitre et al., 2016; Van Wilgen et al., 2012). Limits to usefulness and accuracy The extent to which this indicator can be used is constrained by limited spatial information on a wide range of ecosystem services (although information on some of the more important services are available at a range of scales), accurate distribution maps for biological invasions, and studies that have accurately quantifi ed impacts, and on which models can be based. However, as better information becomes available, this could become an infl uential indicator for informing policy-makers of the consequences of invasion. Updating the indicator This indicator should be updated at the same frequency at which levels of invasion are assessed. Closely related indicators DEPENDS UPON LINKS WITH REQUIRED FOR 5. Number and status of alien species 6. Extent of alien species 7. Abundance of alien species 8. Impact of alien species 9. Alien species richness 10. Relative alien species richness 11. Relative invasive abundance 13. Quality of regulatory framework 14. Money spent 15. Planning coverage 15. Planning coverage 20. Eff ectiveness of species treatments 21. Eff ectiveness of area treatments B. Number of invasive species that have major impacts C. Extent of area that suff ers major impacts from invasions D. Level of success in managing invasions Additional information and comments The choice of what to measure in terms of the impact of invasions will be infl uential and the importance of diff erent impacts will be context dependent. A “minor” reduction in biodiversity in a biodiversity hotspot might be much more important than a “massive” reduction elsewhere; similarly providing the cost of an invasion in absolute terms might hide major and profound societal inequities. APPENDIX 1 – INDICATOR FACTSHEETS 241 13 QUALITY OF REGULATORY FRAMEWORK Use and interpretation This is an input indicator that helps address three key questions: • What regulatory framework is in place to manage biological invasions? • What is the level of completeness of this regulatory framework?; and, • What mechanisms are in place to enable implementation, update, review, and appeal? At a country level, this indicator provides an assessment of the degree to which authorities are able to regulate the cultivation or use of alien species, their transport or trade, and to what extent citizens are required to take steps to control problematic invasive species. Voluntary agreements should also be considered as relevant here. Potential for aggregation This indicator would assess the quality of the regulatory framework at a national level, and there would be no need for aggregation. Can be assessed at lower spatial administrative levels. Possible reasons for upward or downward trends The indicator would change if new regulations are enacted or agreements reached. Implications for biodiversity management of change in the indicator Increases or decreases in the quality of the regulatory framework would aff ect the ability of managers to address the negative eff ects of invasive species. Units in which it is expressed (from basic to advanced) 13.1 Factor with four levels at a national level: • None [there are no regulations (or voluntary agreements) on biological invasions]; and • Partial (regulations are enacted and have clear mechanisms for implementation and enforcement, but only cover some of the aspects of the problem); and • Substantial (regulations are enacted dealing with most aspects of the problem and/or responsibilities are mostly clearly assigned/most mechanisms for implementation, update, review, and appeal are clear); and • Complete (comprehensive legislation governs biological invasions in a holistic way, with responsibilities clearly assigned and clear mechanisms for implementation, update, review, and appeal). 13.2 As for 13.1 but for a range of diff erent administrative entities, and incorporating an evaluation of inter-agency co-operation Description of source data Gazetted legislation applicable to biological invasions; and published codes of conduct. THE STATUS OF BIOLOGICAL INVASIONS AND THEIR MANAGEMENT IN SOUTH AFRICA 2017 242 Calculation procedure 13.1 Assessments by experts on the quality of legislation based on completeness (covers all aspects of pathways, species and areas); mechanisms for implementation; update; and review; and appeal processes 13.2 As for 13.1 at diff erent administrative levels and incorporating an evaluation of inter-agency co-operation Guide for applying confi dence levels 13.1 HIGH Assessment of regulation quality provided by an independent team of experts that includes both invasion scientists and members of the legal profession MEDIUM Assessment of regulation quality provided by either an independent or semi-independent team. The team includes invasion scientists or members of the legal profession but not both LOW Assessment provided by a team who either come from the institution responsible for developing or enforcing the regulations and/or do not contain assessors qualifi ed in invasion science or law 13.2 HIGH As for 13.1 MEDIUM As for 13.1 LOW As for 13.1 Most eff ective forms of presentation 13.1 Table providing a breakdown of coverage of the regulatory framework across all aspects of the problem, on which the assignment to one of the levels is based 13.2 As for 13.1 TABLE A1.3 A table proposed for assessing the quality of regulations pertaining to biological invasions. ASPECT OF REGULATIONS ASPECT OF BIOLOGICAL INVASIONS PATHWAYS (incl. subcategories) SPECIES (incl. diff erent taxonomic groups) AREAS (incl. diff erent spatial scales and ownership) Is there a mandate for management interventions? Detailed /Partial/None Is there provision for enforcement of non-compliance? Is there a requirement for regular assessment of performance, and review? [Document text truncated for crawler view.]