2. iNdiCatorS

2.6. framework

The framework used in this report is shown in figure 2.2, with further details in appendix 1.

high level A Rate of introduction of new

unregulated species

2. introduction rates

3. Within-country pathway prominence 1. introduction pathway prominence

4. Within-country dispersal rates 5. number and status of alien species 6. extent of alien species

15. planning coverage

outputs B Number of invasive species

that have major impacts

high level C extent of area that suffers major impacts from invasions

Figure 2.2 The 21 indicators and four high-level indicators used in this report. Details of the indicators are provided in Tables 2.2–2.6, with factsheets for each indicator in Appendix 1.

Chapter summary

This chapter reports on the status of how alien taxa are introduced to south africa and how they are dispersing and spreading around the country. four indicators were used to evaluate the pathways of introduction and dispersal: (1) Introduction pathway prominence; (2) Introduction rates; (3) Within-country pathway prominence;

and (4) Within-country dispersal rates. an additional high-level indicator, the (a) Rate of introduction of new unregulated species, is also presented and discussed.

There are many different potential pathways of introduction to south africa and the prominence of some of these pathways has increased markedly over time, in particular with increasing trade. The goods, people and transport vessels that are related to these pathways can enter the country through 72 official ports of entry.

alien species are being introduced to south africa through a wide variety of pathways, and although most alien taxa have been intentionally imported into the country, many have been accidentally introduced as commodity contaminants or as stowaways on transport vectors. in addition, some taxa have entered the republic from neighbouring countries through natural spread over the 4862 km-long land borderline, but none have spread into the country through human-built corridors that connect previously unconnected regions (e.g. canals). most alien taxa were originally imported intentionally for the ornamental plant trade and some have subsequently escaped from cultivation.

overall the rate of introduction of new taxa appears to be increasing. for many pathways there has been an increase or no major change in introduction rate since the 1990s, and only a few pathways (e.g. introductions for fishing and aquaculture) are no longer responsible for the introduction of new alien taxa. notably, however, it was not possible to ascribe > 50% of alien taxa to an introduction pathway.

south africa’s extensive and well-functioning transport networks facilitate the transportation of a large, and increasing, amount of goods and people; and so once an alien taxon has been introduced to south africa, further dispersal or natural spread is highly likely. Taxa that are indigenous to the republic can also be dispersed to parts of the country where they are not indigenous. commodity contaminants or stowaways can be dispersed along the extensive transport networks, and there is also a thriving internal trade in species for a variety of purposes. alien taxa may also spread naturally within the country, and utilise human-made corridors like tunnels and canals that connect previously unconnected regions.

for most of the pathways of introduction for which forecasts could be made, an increase in prominence is expected in the future. for some of these pathways control measures are not in place, and unless this changes, further increases in the

PathWaYS of 3

iNtroduCtioN

Lead authors:

Katelyn T. faulkner, John R. Wilson

agriculTure foresTry horTiculTure

mariculTure peT Trade aQuaculTure Most alien species that have established populations outside of cultivation or captivity were introduced deliberately for:

as stowaways on ships and aircraft, others arrive accidentally,

Parthenium hysterophorus (famine weed) – yercaud elango

Tus of biological invasions and Their managemenT in souTh africa2017

3.1. iNtroduCtioN

The processes that lead to the introduction of alien species from one geographical location to another have been termed the ‘pathways of introduction’ (richardson et al., 2011a). These pathways are numerous and involve both the intentional and accidental introduction of alien organisms (hulme et al., 2008). for example, biological control agents are intentionally introduced to manage invasive species from their indigenous range (Zimmermann, moran & hoffmann, 2004), while plant pests are often accidentally introduced when plants are imported from other countries (Kenis et al., 2007; saccaggi & Pieterse, 2013; saccaggi et al., 2016). in this chapter, the term ‘pathways of introduction’ refers to the processes that lead to the introduction of an alien organism to the country, while ‘pathways of dispersal’ refers to the processes that lead to the movement of an alien organism within the country after introduction.

as managing alien species once they have been introduced is difficult and costly (hulme, 2006), it is often more efficient and cost-effective to prevent their introduction (leung et al., 2002; simberloff, 2006; simberloff et al., 2013). To achieve this, information on how and/or why alien species are introduced is used to identify the pathways of introduction and dispersal, and prioritise these pathways for management (hulme et al., 2008; essl et al., 2015a; saul et al., 2017). adequate pathway-specific policies and interventions that target priority pathways must then be developed, implemented and enforced, and their effectiveness monitored (hulme, 2006, 2015;

hulme et al., 2008; essl et al., 2015a; saul et al., 2017). for example, in south africa permits are required when intentionally importing biological control agents (Klein et al., 2011), while imported plant products are inspected at ports of entry for contaminants (saccaggi & Pieterse, 2013).

The importance of such action has been recognised by the convention on biological diversity (cbd), and signatories, like south africa, are required to identify, prioritise and manage their pathways of introduction [see aichi biodiversity Target 9 (uneP, 2011)]. To help countries achieve this, the cbd has adopted a hierarchical pathway categorisation scheme (cbd, 2014; essl et al., 2015a). This scheme recognises six pathway categories (release in nature, escape from confinement, transport - contaminant, transport - stowaway, corridor and unaided), which are divided into 44 subcategories (cbd, 2014; also see figure 3.1). in the scheme a ‘release in nature’ refers to the intentional introduction of an alien organism into the natural environment for the purpose of human use (e.g. biological control agents for the control of alien plants, or trout for angling purposes). an

‘escape from confinement’ refers to the movement of an alien organism kept in confinement into the natural environment, and includes both the accidental and irresponsible release of live organisms (e.g. both escaped and unwanted pets). ‘Transport – contaminant’ involves the unintentional introduction of an alien organism with an intentionally imported commodity (e.g. pests on imported food, animals or plants); while ‘transport – stowaway’ refers to the introduction of an alien organism attached to transport vessels or their associated equipment and media (e.g. hull fouling marine species, hitchhikers in aeroplanes and marine organisms introduced with the release of ballast water by ships). ‘corridor’ involves the natural spread of alien organisms into a new region through human-constructed transport infrastructure that connects previously unconnected regions (e.g. the movement of species through international canals that connect previously unconnected seas);

while ‘unaided’ refers to the natural spread of an alien organism from a region where it was previously introduced, through the above mentioned pathways, to another region where it is not indigenous. The subcategories of the scheme (figure 3.1) enable tailored regulations and interventions to be developed and implemented (essl et al., 2015a; saul et al., 2017).

ChaPter 3IPaThWaYs of inTroduc

The introduction and dispersal of alien species are influenced 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 scientific 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 effectiveness 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 refines 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, socio-economic forecasts were obtained to get an indication of how these pathways might change in future. finally, the effectiveness of pathway related control measures is evaluated and sources of uncertainty addressed (including knowledge gaps). The effectiveness of pathway related control measures and regulations are discussed in chapter 6 and 7 respectively.

facility for mass-rearing biological control agents – Kim Weaver

Tus of biological invasions and Their managemenT in souTh africa2017

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/flora/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 confinement

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 confinement 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/fishing 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

Figure 3.1 The current and forecasted status of the pathways of introduction and the effectiveness 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; Xno 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 effectiveness of control measures (Nk: not known; N/I: none/ineffective; e: effective; 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.

ChaPter 3IPaThWaYs of inTroduc

3.2. data SourCeS

Introduction 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 faulkner 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 faulkner et al. (2015).

dAtA SourCe SCAle oF

national socio-economic information on air

traffic high 1. introduction pathway

prominence

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 scientific 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 fish, 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

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

Tus of biological invasions and Their managemenT in souTh africa2017

affairs (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 fishing 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

global socio-economic information on the

fishing 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 fishing 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, hoffmann &

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 & griffiths (2011)* national historical introduction data for a wide

variety of animals, including fish, 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

ChaPter 3IPaThWaYs of inTroduc 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 fish 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 fishing 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

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 fish, amphibians, birds, mammals and reptiles. information on the fishing, hunting and aquaculture sectors and the within-country dispersal of fish 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

hoffmann (2004) national information on biological control agents

and their within-country dispersal high 4. Within-country dispersal rates

Tus of biological invasions and Their managemenT in souTh africa2017

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

based on socio-economic data, many of the pathways of introduction appear to be playing an important role in

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