LL2-20 — Ch20 Invasive alien species: a growing but neglected threat?#

Late lessons from early warnings: science, precaution, innovation (EEA Report No 1/2013). The chapter sits in Part C, “Emerging issues”. Report pages 486–508 (chapter text pp. 486–502; Table 20.1 p. 502; references pp. 503–508). PDF pages 488–510.

Reading record. I read the whole text extract in order, through the last page marker (PDF 510 / report p. 508). I rendered report pp. 486–502 from the PDF and read them visually. That covered the summary box (p. 486), Box 20.1 (p. 492), Box 20.2 (p. 495), Box 20.3 (p. 496), Box 20.4 (p. 501), Table 20.1 (p. 502) and the passages that looked garbled in the extract. The extract turned out to be faithful. Its only apparent garble, a dangling “invasive species 2011).” on p. 493, is an editing error in the printed original. For standpoint and context I also read, from the same PDF, the author biographies in Annex 1 (pp. 687, 689–693, 697). I also read the passages in other chapters that refer to this one: Introduction pp. 9–10; Ch. 25 p. 609; Ch. 27 pp. 644, 651, 656; Ch. 28 pp. 674–676.

The chapter has no panels or commentaries, from industry, regulators or anyone else. Anything marked [background, unverified] comes from my general knowledge, not from the chapter. It has not been checked in this pass and is kept apart from the record of what the chapter says.

Authors and standpoint#

Six authors. By the report’s own biographies they are senior insiders in the European and global science and policy community on invasive alien species (IAS). Several of them helped build the institutions and instruments the chapter describes.

• Sarah Brunel. Agronomist and scientific officer at the European and Mediterranean Plant Protection Organization (EPPO), Paris. She has “worked for 10 years in the field of biological invasions” with expertise in “pest risk analysis and risk modelling”. Member of the IUCN Invasive Species Specialist Group (ISSG) (p. 687). She co-authored the European Code of Conduct on Horticulture and Invasive Alien Plants (Heywood and Brunel, 2009), which the chapter cites as an example of voluntary codes (pp. 492, 498).
• Eladio Fernández-Galiano. Biologist, former ecology lecturer at the Universidad Autónoma de Madrid, Head of the Biodiversity Unit at the Council of Europe. “He has been in charge of the Bern Convention on Conservation of European Wildlife and Natural Habitats since 1985” (p. 689). The Bern Convention is an actor throughout the chapter. It asked Italy to eradicate grey squirrels in 1999 (p. 492), proposed the European ruddy duck eradication plan (p. 495), ran an IAS working group from 1993, and adopted the 2003 European Strategy on IAS and the codes of conduct (p. 492).
• Piero Genovesi. Senior conservation officer at ISPRA, Italy’s national environmental protection and research institute. Chairs the IUCN SSC Invasive Species Specialist Group (since 2009). Works with the Italian Ministry of Environment, the European Commission and the Convention on Biological Diversity (CBD) “to develop guidelines and policies on the management of alien species” (pp. 689–690). He co-authored the Bern Convention’s European Strategy on IAS (Genovesi and Shine, 2003), the EU cost assessment the chapter relies on (Kettunen et al., 2009) and the published account of the failed Italian grey squirrel eradication (Bertolino and Genovesi, 2003). The ISSG position statement (ISSG, 2011), which the chapter uses to answer critics (p. 494), came from the group he chairs.
• Vernon H. Heywood. Professor emeritus, University of Reading. “An authority on biodiversity, plant systematics and conservation and the conservation role of botanic gardens.” He coordinated the UNEP Global Biodiversity Assessment and now works on “the effects of global change in Europe and the Mediterranean and its impacts on biological invasions” (pp. 691–692). He co-authored the horticulture code and wrote the botanic gardens code (Heywood, 2011).
• Christoph Kueffer. Senior scientist at ETH Zürich. Research on “ecological change in the Anthropocene, with a focus on oceanic islands and mountains, and expertise in transdisciplinary research”. Coordinates the Mountain Invasion Research Network (pp. 692–693). Much of the chapter’s reflexive, social-science and transdisciplinary framing draws on his work: Kueffer and Hirsch Hadorn (2008), Kueffer (2010), Kueffer et al. (2010), McDougall et al. (2011).
• David M. Richardson. Deputy Director, Centre for Invasion Biology, Stellenbosch University. Editor-in-chief of Diversity and Distributions and editor of Fifty years of invasion ecology: the legacy of Charles Elton (2011). ISSG member (p. 697). His work supplies the chapter’s history of the discipline and its conceptual frameworks: Richardson et al. (2000, 2011), Richardson (2011a, b), Blackburn et al. (2011).

Collective standpoint. These are participant-advocates: the regional plant-protection body, the Bern Convention secretariat, the global IAS specialist network and two leading academic invasion biologists. By my count, about 35 of the roughly 120 reference entries (about 30%) are authored or co-authored by one of the six, plus the ISSG (2011) statement. That gives the chapter authoritative inside knowledge, for example of what the pet and horticulture industries prefer (p. 499) and how the Italian eradication ended (p. 495). It also means the chapter is partly an account of the authors’ own institutions and campaigns. Their roles are not disclosed in the chapter text; they appear only in Annex 1. Examples: Genovesi co-wrote the published account of the grey squirrel eradication; the Bern Convention, which Fernández-Galiano has been “in charge of” since 1985 (p. 689), issued the 1999 request to Italy.

Evident stance. - Strongly pro-prevention and pro-early-eradication. The chapter treats “preventing biological invasions or tackling them at a very early stage” as “the most efficient and cost-effective approach” and says this is “widely agreed” (p. 487). - Critical of political neglect, especially in the EU. “the full range of problems associated with IAS still lacks political recognition” (p. 487). Box 20.4 accuses European governments of using the need for EU coordination as “an excuse for inaction” (p. 501). - Reflexive about its own field, more than most Late Lessons chapters. It admits terminological confusion (pp. 487–488, 493), poor data (p. 488), early research disconnected from management (p. 500), the assumption that “any detectable effect of an alien species on an ecosystem would be undesirable” (p. 500), and poor communication by scientists (p. 499). - Qualified on the precautionary principle. It invokes precaution as the basis for rapid response (p. 487) and notes it is the first CBD Guiding Principle (p. 498). But it concedes that “rigid application” is “problematic in the context of free-trade agreements” (p. 497), and that where to draw the line is “a value judgement” requiring “a societal debate” (p. 497). - Impatient with philosophical and definitional debate that it sees as blocking action (pp. 493, 502). At the same time it asks for expert disagreement to be made transparent (p. 499). This tension is discussed below.

Character of the chapter. This is not a single-agent case study like most Late Lessons chapters. It is a review of a whole class of hazard and of how science and governance around it have developed. The “technology” at issue is diffuse: global trade, travel and the deliberate movement of organisms for horticulture, pets, fisheries, crops, forestry and biological control. Table 20.1, “Early warnings and actions”, is mostly a history of the science and its institutions (Pliny, Darwin, Elton, SCOPE, CBD, databases). Apart from Pliny’s rabbits and the CBD’s legal duty, it does not record specific warnings and the responses to them. The main “late lesson” narrative is compressed into Box 20.4 (EU delay) and a handful of mini-cases.

Section-by-section notes#

Summary box (p. 486)#

• Biological invasions are “one of the five major causes of biodiversity loss”. Travel and trade move “thousands of species between and across continents”. “Some species of alien origin have a high probability of unrestrained growth which can ultimately lead to environmental damage.” (The body text on p. 495 is more careful: “a higher probability”, i.e. relative to natives.)
• Definitions. An alien species is one introduced by human activity, accidentally or deliberately, “to an area it could not have reached on its own”. “A common definition of the term ‘invasive’ focuses on its (negative) impact, while other definitions consider only rate of spread and exclude considerations of impact.”
• Headline claim. “Despite the growing amount of legislation being adopted at the global scale, biological invasions continue to grow at a rapid rate, with no indication yet of any saturation effect.”
• Governance difficulty. Complexity, interdisciplinarity, scientific uncertainty and the number of stakeholders “together demand governance actions that are difficult to see emerging at the regional scale (as in the EU), let alone globally”.
• Prevention and early action are “widely agreed” to be most cost-effective. Misidentification works both ways: harmless species mistaken for harmful ones waste resources, and “harmful invaders can be mistaken for innocuous species — so-called ‘invaders in disguise’”.
• Even with good risk assessment, outbreaks will occur, so rapid early warning and eradication are needed. Where to draw the line between acceptable risk and new introductions “becomes a value judgement”.
• Management strategy is debated within science: there is “lively debate within the scientific community regarding the most appropriate strategies for managing invasive alien species”. Decision-makers have “considerable knowledge, but the lack of rules of interactions between multiple parties regularly thwarts effective decision-making”.

20.1 Introduction (p. 487)#

• Place among threats. Invasions are one of five major causes of biodiversity loss, with habitat destruction, over-exploitation, climate change and pollution (Millennium Ecosystem Assessment, 2005).
• Attrition across invasion stages. [My gloss, not the chapter’s: this resembles the “tens rule”, which the chapter does not name or quantify.] “Only a small proportion of alien species become established, some of these spread, and a small subset produce major ecological, economic or social effects.” Impacts include local extinction, lower native diversity, and ecosystem changes such as altered nutrient cycling or water quality.
• Extinction evidence. Of 680 recent animal extinctions, causes were compiled for about 25%. Of those, 91 (54%) included invasive species among the causes, and in 34 cases invasive species were the only known cause (Clavero and Garcia-Berthou, 2005). Feral cats on islands are responsible for “at least 14 % of global bird, mammal, and reptile extinctions in recent times” (Medina et al., 2011).
• Scope. All types of organism, “from micro-organisms … to mega-herbivores”, and all ecosystem types can be affected.
• National responses. Some countries have comprehensive legislation or strategies: Australia, Great Britain, Mexico, New Zealand, South Africa, USA (Pyšek and Richardson, 2010).
• Cost of delay. “the cost of eradicating weeds can increase at least 40 times if action is not taken promptly” (Harris and Timmins, 2009; [background, unverified: a New Zealand Department of Conservation study; the chapter does not say so]). “in most cases eradication quickly becomes unfeasible” (Genovesi, 2007).
• Precaution defined as speed. “Preventive management calls for a precautionary approach, because prompt response often does not permit full assessment of the risks connected to a newly detected invasion” (Genovesi et al., 2010). Precaution here means acting before a full risk assessment is possible, because the window for effective action closes fast.
• Neglect claim. Despite agreement on these principles, IAS “still lacks political recognition and too few government-coordinated actions are in place, or are effective, in most parts of the world, including in the European Union”.
• Framing. “This is more a human-driven environmental problem than a strictly biological one.” “Inherent uncertainties remain about what species will be introduced and which will become invasive. Consequently, making decisions is very challenging.”
• Learning across places. “Lessons already learnt in different parts of the world need to be considered when seeking to improve management regimes for IAS in different environments and at different scales” (p. 487). (Relevant to the Caulerpa France/California comparison, p. 498, where the chapter does not draw this lesson explicitly.)

20.2 The difficulty of defining invasive alien species (pp. 487–488)#

• No universally accepted definition, and “all this has serious practical consequences” (p. 487).
• “Alien” needs a reference area, which may be a continent, island, bioregion or political unit (Lambdon et al., 2008). “The terms alien and invasive both have political overtones” (p. 487).
• CBD Article 8(h) requires Parties to “prevent the introduction of, control or eradicate those alien species which threaten ecosystems, habitats and species”. The CBD defines IAS as “alien species whose introduction and/or spread threaten biological diversity”, an impact-based definition (p. 487).
• The biogeographic alternative defines invasive species as aliens that “sustain self-replacing populations, often in very large numbers at considerable distances from the site of introduction”, and “explicitly exclude considerations of impact”. Other definitions add economic and social or health impacts (p. 488).
• The split between academia and policy. “the biogeographical concept is more widely used in the academic world, whereas the impact concept is widely used by decision makers” (Ricciardi and Cohen, 2006). “Such terminological and conceptual problems have contributed to difficulties in developing a coherent and effective political response” (p. 488).
• Information growth and its limits. Information has grown over 20 years; the Global Invasive Species Database dates from 2000 and was “the first web-based, freely accessible database on invasive species”. But “accurate and comprehensive information on global or regional numbers of invasive alien species is still difficult to obtain”. “Even taxonomic reference works such as Floras and Faunas are notoriously bad at distinguishing between native and alien species” (p. 488).
• Misidentification. Harmless species are confused with harmful ones, and harmful invaders pass as innocuous: “invaders in disguise” (Verloove, 2010) (p. 488).
• Europe, relative to elsewhere, has “generally good information”, and many countries have lists, but “under-recording remains a problem” (p. 488). The DAISIE database has gaps. Examples of confusion:
• Heracleum mantegazzianum and Fallopia japonica are “frequently confused with related species”;
• invasive hybrids called Rhododendron ponticum have been renamed R. × superponticum;
• experts disagree whether Opuntia maxima and O. ficus-indica are separate species (p. 488).
• Outside Europe few countries have updated lists. McGeoch et al. (2010), reviewing 57 countries, found IAS counts ranging from 9 to 222, “reflecting as much a lack of information as real differences of incidence” (p. 488).
• A misleading statistic. Pimentel et al. (2005) estimated that 50,000 alien species have entered the US. “This figure is, however, misleading unless broken down”: the 25,000 alien plants (against a native flora of about 17,500) “includes agricultural and horticultural crops, timber and ornamental trees, garden plants, and weeds!” (p. 488). The chapter later uses cost figures from the same Pimentel paper without caveat (p. 494); see the bias check.
• Lists don’t combine. Lists compiled by the late 1990s lacked “coordination and harmonisation”. Aggregating lists built on different criteria “makes the interpretation of data and the planning of common action difficult and laborious” (p. 488).

20.3 Emergence of awareness of an old problem (pp. 488–490)#

• Ancient awareness. Pliny the Elder (77 AD) described rabbits in the Balearic Islands as “a very severe problem requiring effective control” (p. 488).
• Darwin noted invasive behaviour on the Beagle voyage. The chapter says this “contributed to the development of his theory of the ‘survival of the fittest’ (Darwin, 1859)” (p. 489). Table 20.1 (p. 502) more accurately says “natural selection”. [Background, unverified: “survival of the fittest” is Herbert Spencer’s phrase (1864), which Darwin adopted in later editions of the Origin.]
• Curiosities, not threats. “In most cases, however, alien species at that time were regarded as curiosities, rather than a significant threat” (p. 489).
• Nineteenth-century concern about impacts on native vegetation, especially on islands. J. D. Hooker (1864) wrote of how some introduced species “rapidly displace the aborigines and replace them” (p. 489).
• Elton (1958), The Ecology of Invasions by Animals and Plants, is widely seen as the founding text of invasion biology (Richardson and Pyšek, 2008). Kueffer and Hirsch Hadorn (2008) note an older European tradition rooted in 19th- and early 20th-century floristic studies of adventive species, which “already considered the role of humans as agents” (p. 489).
• Europe was slow. “In Europe, in particular, these concepts were slow to manifest themselves widely; for many biologists and conservationists, biological invasions were still perceived as happening ‘somewhere else’ (rabbits in Australia, water hyacinth in African lakes and waterways, etc).” Wide acknowledgement came only “in the last two decades of the 20th century” (p. 489).
• SCOPE I (1980s), the international programme on the Ecology of Biological Invasions, had a strong conservation focus. It shaped the framing and core questions of the field and showed “the global scale of the problem” (p. 489). Table 20.1 says it “led to an explosive growth in invasion biology” (p. 502).
• CBD in force end of 1993. IAS became a cross-cutting issue, and COP decision VI/23 adopted the Guiding Principles (p. 489; dated 2002 in Table 20.1).
• SCOPE II (1997) was more inter- and transdisciplinary, covering “economic valuation, stakeholder participation, pathway analysis and management”. It ran under a consortium (SCOPE, IUCN, CABI) that created the Global Invasive Species Programme (GISP). Wittenberg and Cock’s Toolkit (2001) synthesised 2000s thinking. “In 2011 GISP was closed down, for financial reasons” (p. 489).
• European research was “limited and uncoordinated until the late 1980s”. Ambitious EU programmes began in the early 2000s, such as DAISIE and ALARM (pp. 489–490).
• Information infrastructure. Databases and clearing houses: GISIN, GISD, the Invasive Species Compendium, I3N for the Americas, NOBANIS for northern Europe and the Baltic (p. 490).

20.4 A new discipline with its own approaches and research agenda (pp. 490–491)#

• Caveat on sequence. The section follows Kueffer and Hirsch Hadorn (2008) in distinguishing approaches (classical trait model, phase-transition models and risk assessment, pathways, landscape, socio-economic). The chapter warns that “all these elements have coexisted over time” (p. 490), so they are analytic categories, not strictly successive eras.
• The classical SCOPE I model asked three questions (p. 490):
• which traits make a species an invader;
• why some habitats are more vulnerable than others;
• how management could use this knowledge.

Research was mostly population and community ecology based on biogeographic comparison, “the underlying assumption being that the alien origin of species was important for explaining their behaviour”. - A central negative result. “Despite many studies … no single/common list of traits emerged that distinguish invasive from non-invasive species.” The best criterion is invasiveness elsewhere (“assuming that it has had the opportunity to do so”). That is “a powerful predictor … although this criterion must be used with great caution in a world of rapid global change” (Kueffer, 2010) (p. 490). - Phase-transition models. Invasion is broken into entry, establishment “after a possible lag phase during which the population size of the species remains small”, and spread. The idea is older (Usher, 1986) but became central to theory “since around 2000” (Richardson et al., 2000; Kolar and Lodge, 2001; Blackburn et al., 2011). The chapter adds that the model “also facilitates taking into account climate and global change” (p. 490). - Risk assessment emerged in the same period, e.g. Pheloung et al. (1999) [background, unverified: the Australian weed risk assessment; the chapter does not name it]. Its aim is to identify likely invaders, “including those not yet introduced into a territory” (p. 490). - Staged management follows from the phase model: prevention at borders as priority, then early detection and eradication, then “sustained containment and mitigation of impacts as the last option” (Wittenberg and Cock, 2001) (p. 490). - Pathways. After SCOPE II and GISP, pathways became an active research area, “integrating natural and human sciences, since human activities are the central cause of movement of species”. Listed pathways: trade and travel, wars, shipping and ballast water, trade in plants and animals, intentional economic introductions, tourists, accidents (p. 490). - Landscape perspective was “largely neglected” until around 2000, including the role of land-use change (pp. 490–491). - Biology and society interact. “biological and social factors interact in complex ways”, and economic factors drive introduction and spread (Kueffer et al., 2010; Pyšek et al., 2010; Essl et al., 2011; Jeschke and Genovesi, 2011). Research on impacts on ecosystem resilience and services is growing (EFSA, 2011) (p. 491). - Science driving policy. Advances in understanding “had a significant influence on awareness of the issues”. European institutions’ recent move to stricter measures “may also have been helped by an assessment showing that … the economic costs of invasive alien species in the region exceed EUR 12.5 billion/year” (Kettunen et al., 2009) (p. 491). Note the hedge: “may also have been helped”. - Eradication works. Eleven birds, five mammals and one amphibian improved in conservation status after IAS removal (McGeoch et al., 2010). More than 1,100 eradication campaigns have been run worldwide (Genovesi, 2011). In Europe they are “uncommon”, with examples being Carpobrotus on Menorca and ruddy duck in the UK, France and Spain (p. 491).

20.5 A wealth of initiatives worldwide (pp. 491–493), with Box 20.1 (p. 492)#

• Treaties. At least 42 treaties on environment, marine and quarantine matters refer to IAS (Riley, 2005). The International Plant Protection Convention (IPPC) sets phytosanitary standards, though “it only covers non-marine invertebrates and plants”; it extended its scope in 1999 to wild plants and the environment. The CBD and IPPC signed a Memorandum of Understanding in 2004 to avoid duplication, which required revising glossaries and procedures. These bodies “have counterparts at the regional scale, and countries are obliged to implement legislation on IAS” (p. 491).
• Governments. Governments and parliaments are credited with a “major role”: adopting and enforcing legislation, conducting or financing eradication, and promoting research and public awareness (p. 491). Responsibility is usually split between environment and agriculture ministries, with health, energy, infrastructure and transport also involved. Agriculture ministries hold the plant and animal health regimes. “Although the environmental and agricultural sectors cooperate at the international level, the mandates are not always clear at the national level.” The chapter explains this by pest management’s “longer history than control of invasions” and the difficulty of categorising multiple impacts (p. 491). Dedicated legal instruments exist in Australia, New Zealand, the USA, South Africa and the UK, and the number of legal tools “has increased steadily” (p. 491).

Box 20.1, “Varying European approaches for dealing with IAS” (p. 492). - No EU framework. Despite many studies (e.g. Miller et al., 2006), “no comprehensive regulation or legislative framework for the EU is yet in place”. - Scale. “Partly as a result of the lack of coordinated action”, Europe houses around 11,000 alien species (DAISIE). About 10% (1,094) have ecological impacts and 12% (1,347) have economic impacts (Vilà et al., 2010). - Harmful species remain on sale. Species that countries “spend millions of Euros in managing and controlling can still be freely purchased”: - Water hyacinth (Eichhornia crassipes) caused “spectacular invasions” in Portugal, Italy and along 75 km of a Spanish river. Control took “a few months and 18 million Euros” (Cifuentes et al., 2007), yet it “can still be bought and traded freely in the EU”. - Grey squirrel (Sciurus carolinensis) has replaced the native red squirrel in most of Britain, yet was released in Italy at three sites, in 1948, 1966 and 1994. The Bern Convention asked Italy in 1999 to eradicate “without further delay” and to prohibit trade. “twelve years later it is still legally offered for sale in pet shops, while the invasive population continues to grow in the absence of any efforts to control or eradicate it” (Standing Committee to the Bern Convention, 2011). - The legal landscape is “complex, fragmented and continually developing” (Miller et al., 2006): - EPPO sets regional phytosanitary standards; - the Bern Convention (1979), Article 11, commits parties to strict control of introductions, and has had an IAS working group since 1993; - EPPO and the Bern Convention jointly published the European Code of Conduct on Horticulture and Invasive Alien Plants (Heywood and Brunel, 2009). - Uncoordinated national legislation. Norway has comprehensive legislation. Germany and Austria are developing a regulated list (GABLIS). The UK is working on one. Spain legislated in November 2011, Switzerland in September 2008. “However, given that the regulation of trade in the EU lies within the European Commission, all these efforts will only have limited effectiveness until there is a legal tool that can be applied across the EU.” The Commission is preparing an instrument “to be ready by the end of 2012” (COM, 2011). Some matters will always suit national regulation. - Why there is no coordinated approach. Neither the Bern Convention (45 states) nor the Habitats Directive (EU-27) is specific on IAS; both were drafted before IAS became a major concern (1979, 1992). - Bern: “strictly control the introduction of non-native species”. - Habitats Directive: “ensure that the deliberate introduction into the wild of any species which is not native to their territory is regulated … and, if they consider it necessary, prohibit such introduction”. - Neither covers prevention, pathways, unintentional introductions, containment, early detection or rapid response. - The Bern European Strategy (2003) and the Commission’s technical documents for the EU Strategy (2011) “do contain sufficient guidance for precise government action”, but “they are not legally-binding documents and their application has been patchy”. - National plant protection organisations want invasive alien plants included in the revised Plant Health regime (Agra CEAS Consulting et al., 2010).

Back in the main text (p. 493). - The EU “has committed to presenting a draft dedicated legal tool by the end of 2012”, and an assessment of legal options was published in December 2011. - National strategies exist in Canada (2004), South Africa (Cape Floristic Region, 2009), Mexico (2010), the Bahamas and several European countries. - A sentence on “large interdisciplinary programmes” ends with a dangling citation (“invasive species 2011).”) in the printed original. - NGOs. The IUCN ISSG is “one of the oldest organisations active in this field”. A footnote gives its founding year as 1993, “the first thematic (as opposed to taxonomic) specialist group”, with about 1,000 volunteer members. Table 20.1 instead calls it the “first interdisciplinary specialist group”. Other NGOs: CABI, BirdLife, The Nature Conservancy, Wildlife Conservation Society, and Island Conservation, whose mission is “to prevent extinctions by removing invasive species from islands”. There are “thousands of associations or foundations” locally. - Universities. Research spans biology, weed science, agronomy “and more recently social science”, with networks and conferences such as NEOBIOTA and EMAPI. - Conclusion of the section. “Thus, despite the growing amount of legislation being adopted at the global scale, invasions continue to grow at a rapid rate, with no indication yet of any saturation effect” (Butchart et al., 2010). There is heavy reliance on “voluntary codes of conduct which by definition lack sanctions for non-compliance”, the latest being the European Code on Pets and IAS (Davenport and Collins, 2011). None of this is helped by definitional difficulty. “It is therefore not surprising that the scientific community recurrently undergoes soul-searching over these issues.”

20.6 Obstacles to a common understanding (pp. 493–496)#

• A long controversy. The extent of IAS harm “has long been a subject of controversy, not just between stakeholders with different interests (e.g. conservationists versus horticulturists/foresters) but also within the scientific community”. Dissenting voices periodically challenge whether IAS are a major threat and what should be done; the chapter points to the Sagoff (2005) and Simberloff (2005) exchange (p. 493).
• Debate can be harmful. “Although debates and discussion are inherent to the development of any discipline, too much focus on these controversies can have a deleterious effect” (p. 493).

“Dissenting voices about the ‘pros’ and ‘cons’ of managing IAS” (p. 494). - A hybrid definition. Because IAS are defined by negative impact, “the very definition of IAS along these lines is therefore somewhat of a hybrid, mixing biological elements (a species), the effects on the environment that we are able to detect, and human perceptions” of impacts. Impact assessments “are subject to multiple interpretations” and “particularly difficult in the context of a precautionary management approach that builds on an ability to predict potential future impacts”. - Where agreement ends. Some IAS clearly have major impacts that would ideally be prevented. But views diverge on “how common problematic alien invaders are and whether the alien origin of a species is a reliable heuristic for predicting problematic spread”. - The critics’ case. Davis et al. (2011, “Don’t judge species on their origins”, a two-page Nature piece with 19 authors per the reference list) “question whether conservation money is efficiently spent on preventing the introduction of any new alien species until such species are proved innocuous, as a strict interpretation of the precautionary principle would require”. The chapter summarises: “they highlight the opportunity costs of a strict prevention of introduction of alien species, including the opportunity costs of losing the benefits that some alien species might provide”. - The ISSG response (2011), from the group Genovesi chairs: - escalating biodiversity loss motivates action; - “alien species may not manifest invasiveness till decades after their introduction”; - some species with subtle immediate impact eventually affect whole ecosystems, e.g. through soil properties. - Context-dependence (the chapter’s own addition, not clearly part of the ISSG reply). “In addition, invasions and impacts appear to be context-dependent. This is particularly true for plants.” Alien cinnamon (Cinnamomum verum) has been considered “potentially beneficial” for restoring novel mid-elevation forests in the Seychelles but is “a major invader in nearby montane cloud forests” (Kueffer et al., 2010, co-authored by Kueffer). The example cuts both ways: it supports the critics’ point that some aliens bring benefits as well as the defenders’ point that harm is hard to foresee. - The ISSG conclusion. The ISSG “argues that, irrespective of how common problematic invasions of alien species are, prevention is needed because of the huge impacts of the invasions that do happen”. - Cost of inaction. “Based on such a perspective”: - up to USD 1.4 trillion per year, “about 5 % of global GDP” (cited to Pimentel et al., 2005); - USD 138 billion per year for the US; - USD 14.45 billion for China (2000; 1.36% of GDP); - over EUR 12 billion per year for Europe.

The US and China figures carry no citation of their own in the chapter. The European figure is given here as “over EUR 12 billion” and “EUR 12 billion”, but on p. 491 as exceeding “EUR 12.5 billion/year”, both apparently from Kettunen et al. (2009).

“While the cost of inaction in Europe is EUR 12 billion per year, the cost of action is estimated at EUR 40–190 million per year, depending on the possible policy options (Kettunen et al., 2009). The management of IAS is therefore, according to this perspective, considered a very cost-effective investment.” The phrase “according to this perspective” puts some distance between the authors and the claim. - The authors’ pragmatic resolution. “It is not, however, obvious how to decide on priorities and what actions should be taken … when such benefits and harm cannot be predicted. The solution may come from a pragmatic approach that involves prevention or mitigation of the worst impacts of invasives through a combination of preventive measures, early detection and rapid response to new incursions, with permanent management as only the last option.”

“The lack of acceptance by society of some management actions” (p. 494). Management is criticised when it involves killing animals, biological control agents or pesticides and herbicides (Boxes 20.2, 20.3). Opponents of controlling invasive plants may see herbicides “as a bigger threat than the actual impacts of the invasives”.

“Native vs. alien: a polemical topic to explain to the public” (pp. 494–495). - A common confusion. People often fail to distinguish invasive species from alien species and use that to justify action against aliens in general. - Social scientists’ critique. Larson (2007) and Warren (2007) point to “problematic social and cultural connotations of such ‘prejudice’ against species of non-native origin”. “Some consider that environmentalists, conservationists and gardeners are ‘xenophobic’”. The press does use pejoratives such as “the yellow peril” for water primroses (Ludwigia grandiflora, L. peploides) in southern France. - The authors’ reply. “from a scientific point of view, the focus on alien species is not xenophobic but has a scientific basis” (the text cites “Simberloff and 141 scientists, 2001”, but the reference list has 2011). Aliens are singled out “not because they are considered unwanted per se, but because they show that some species of alien origin have a higher probability of unrestrained growth”. One reason is escape from natural enemies (enemy release).

Box 20.2, “The grey squirrel and the ruddy duck: too cute to be killed” (p. 495). - Grey squirrel, Italy. “The two officers in charge of the eradication of grey squirrel were brought to court and charged with cruelty toward animals and illegal methods of capture, despite consultations with animal welfare groups and exercising caution in killing the animals. The legal case delayed the enforcement of any action, ruining the whole eradication campaign.” The squirrel “is now expected to spread across Europe, with huge impacts on biodiversity as well as the economy of the entire region” (Bertolino and Genovesi, 2003; Bertolino et al., 2008). The box gives no dates for the attempt or the trial. The only view presented is that of the eradicators. - Ruddy duck. The ruddy duck (Oxyura jamaicensis) escaped from captivity in the UK, reached “several thousand”, spread through Europe and hybridised with the endangered white-headed duck (O. leucocephala), threatening Spain’s “very intense efforts” to prevent its extinction. Selective shooting in Spain was only temporary. The long-term solution was eradication at source in the UK. The Bern Convention proposed a European plan, and the UK government and EU financed eradication “from 1997”. “Shooting attractive ruddy-ducks caused a public and vociferous outcry in that bird-loving country, until the support of the Royal Society of the Protection of Birds for the controls was decisive in getting the project started. That courageous decision cost the society the loss of probably a few thousand members.” By December 2011 UK numbers were down to “a few hundred”, with “good chances of eradicating the species from the wild in Europe by 2015” (Standing Committee to the Bern Convention, 2011; “Consulting et al., 2010”, a garbled citation).

“An even greater difficulty in defining what is ‘natural’” (p. 495). - Novel ecosystems. Davis et al. (2011) argue that “natural” ecosystems of the past “have changed forever” through climate change, nitrogen eutrophication, urbanisation and land use. Most communities now mix long-term residents and newcomers, and “novel ecosystems” (Hobbs et al., 2006) or “no-analogue ecosystems” (Williams and Jackson, 2007) are emerging. - Emerging challenges (Kueffer, 2010): - novel alien crops “such as those used for biofuel and biomass present a risk of favouring new invasions” (Genovesi, 2010; Sheppard et al., 2011); - “synthetic biology may in the near future produce still more fundamentally novel species”; - assisted migration or colonisation of natives to escape climate change risks new impacts, “as in the case of the proposed translocation of the Iberian lynx into the British Isles” (Thomas, 2011; Vilà and Hulme, 2011).

Box 20.3, “Fear of biological control agents” (p. 496). - The authors’ view of caution. Biological control “triggers reluctance in decision makers and the public, though generally supported by scientists if proper and conclusive research has first been carried out. Such caution prevents this efficient technique from being used when IAS are widespread.” - Sources of mistrust. The fear is non-target attack, “thus aggravating the problem instead of solving it”. The public also “finds it odd and risky to introduce a new non-native species into a complex ecosystem, particularly in a psychological context of negative feelings towards alien species. Often scientists are not fully trusted either.” - Cactoblastis cactorum controlled “millions of hectares” of invasive Opuntia in Australia, South Africa, Hawaii and the Caribbean. It was then accidentally introduced to Florida, where it threatened a native Opuntia (Sforza, 2006). “the potential for accidental spread … had not been assessed accurately.” The chapter calls it “a typical example that is used to oppose biological control”. - Cane toad (Rhinella marina), introduced to Queensland against sugarcane insects, naturalised and spread, preying on many animals and competing with native amphibians. “the potential adverse impacts … had not been assessed accurately.” - Cibdela janthina, released in Réunion in 2009 against Rubus alceifolius, set off “intense debate in the media”. Beekeepers and fruit growers feared it would outcompete bees, and the issue reached the French Senate (21 May 2009). “After undertaking additional studies and dialogue with stakeholders, it finally appeared that Cibdela janthina had no impact on bees, and was efficient at controlling the targeted plant.” - Confidence in modern assessment. Agent selection is now studied “through formal risk assessment protocols (the same as those used for IAS) that greatly reduce the chance of unexpected behaviour of released species”. - A regulatory asymmetry. “At a European level, legislation on the introduction of biological agents is quite stringent, while legislation against the introduction of any other species, including acknowledged invasive ones is non-existent.” - Water hyacinth in Spain. Authorities “ruled out the introduction of a biological control agent, used successfully in Africa, because of the complex European legislative framework impeding the release of agents”. - Aphalara itadori was released in the UK against Japanese knotweed (Fallopia japonica), whose management costs “more than GBP 150 million a year”. This was “the first classical biological control release against an invasive alien plant in Europe”, after five years of CABI testing. A public consultation drew 20 responses against and 42 in favour (CABI, 2010).

20.7 The limits of governance on the complex issue of IAS (pp. 496–497)#

• Which framework is in charge? Interdisciplinarity “can slow action and cooperation”. An IAS may have environmental and agricultural impacts and also provide agricultural benefits, which raises the question of which legislative framework applies. At EU scale, “various principles, terminologies and legislative frameworks need to be aligned before any decision can be taken” (p. 496).
• Ragweed (Ambrosia artemisiifolia): highly allergenic pollen and a crop weed, especially in sunflower. “Discussions on which department — health or agriculture — should deal with the problem has much delayed measures to control the species” (pp. 496–497). No dates or quantities are given.
• Classical tools fail. “Classical environmental management tools (i.e. habitat protection, liability for environmental damage or mediation in environmental conflicts) prove of little use for IAS” (p. 497).
• Lag phase and liability. “before becoming invasive, a species may remain unnoticed in an area for several decades, the so-called ‘lag phase’”. This makes liability “very difficult, as the traceability of who introduced a species may be lost with time” (p. 497).
• Mediation is “handicapped by uncertainty in the potential invasive behaviour of an introduced species, as the decision on whether or not to introduce a species needs to be taken far in advance of the species becoming effectively invasive” (p. 497).
• Signal crayfish (Pacifastacus leniusculus) (p. 497). Crayfish plague damaged Scandinavian fisheries of the native European crayfish (Astacus astacus). North American signal crayfish were then introduced to Norway and Finland for recreational and commercial capture. “It turned out that signal crayfish was not only the carrier of the crayfish disease, but it also became invasive”, threatening native crayfish, macro-invertebrates, benthic fish and aquatic plants. It “is now out of control”. It also “has beneficial effects for crayfish production, resulting in a conflict of interest between those who want to control the species and those who want to breed it. Clearly a decision should have been taken long before allowing the introduction of this species in Europe.” No dates are given.
• Risk assessment is slow and imperfect. It is “a time-consuming exercise”, and “even with a very good risk assessment system, new outbreaks of IAS could still occur”, so rapid early warning and eradication are needed. Where to draw the line “becomes a value judgement to be taken by governments” (p. 497).
• Proportionality. The range runs from “allowing the entry of any species versus prohibiting the entry of all non-native species”. It “is very delicate and should involve, in addition to the strategic position of governments, a societal debate”. That requires “good knowledge by the public”, and both introducers and “the public who are often responsible for the entry or further spread of these species” need to be engaged (p. 497).
• Geographic proportionality in a single market. A species may be harmful only in one bioclimatic zone, but trade is free across the EU. “should the attractive water hyacinth (Eichhornia crassipes), which in Europe may only become naturalised and be invasive in Mediterranean countries, be prohibited from trade in the United Kingdom where it is harmless?” The UK nursery industry might want to sell it, but free movement “might compromise management efforts in areas at risk” (p. 497).
• Law and voluntarism together. “The question of balance between legislative and voluntary approaches in dealing with IAS is crucial. As many stakeholders are involved, both approaches are needed, the one reinforcing the other” (p. 497).

20.8 Applying the precautionary principle to invasive alien species (pp. 497–498)#

• Trade constraint. “Because of the lack of robust criteria for predicting invasiveness, and because most research on biological invasions assumes that alien species are ‘guilty until proven innocent’, rigid application of the precautionary principle in managing biological invasions is problematic in the context of free-trade agreements” (p. 497).
• Two regulatory models.
• White list, New Zealand (“white list” is my label; the chapter does not use it). “every species imported to the country is assessed for risks, and only if found to pose a low risk can an authorisation be issued” (p. 497).
• Black list. Other countries regulate only species on a list of “unwanted” invasive or potentially invasive species. The IPPC also proposes this (p. 498). A footnote says these “used to be called ‘Black lists’, but such a term is now not considered politically correct” (p. 498 fn 10).
• Precaution as rapid eradication. “Another way of applying the precautionary principle, while not preventing the entry of IAS, is to eradicate new invaders in a timely manner” (p. 498).
• Caulerpa taxifolia, “a missed opportunity”. The alga “was detected in France in 1984 at a very early stage of invasion, and could have been quickly removed”. Management began only when it “had already expanded to a large portion of the Mediterranean, when eradication was no longer possible”. In California in 2000, “eradication started only 17 days after its discovery, leading to its successful removal” (Genovesi, 2007) (p. 498). The chapter does not say who knew what in 1984 or why action was delayed. [Background, unverified: the 1984 find is usually placed off Monaco, below the Oceanographic Museum. The alarm was raised by French researchers from 1989. Check.]
• Precaution in the international rules. It is the first of the CBD Guiding Principles (Annex to Decision VI/23; Cooney, 2004). The IPPC applies it “to some extent” by considering all sources of uncertainty in pest risk analysis (p. 498).
• Biosecurity as a research field. It is “very dynamic”, using niche modelling and pathway analysis. It must identify species that “may be invasive under novel conditions created by climate change and/or other facets of global change”, for example through ecosystem-services scenarios (EFSA, 2011; Chytrý et al., 2012) (p. 498).

20.9 Addressing invasion pathways: a late engagement with the stakeholders (pp. 498–499)#

• From species to pathways. Emphasis has shifted to pathways and stakeholders, “although such aspects have been adopted quite recently considering the history of the discipline”. The focus has moved “away from preventing particular species to managing risks associated with introduction pathways, including the human activities that create, shape and sustain such pathways … involving local knowledge”. Social scientists now study perceptions (p. 498).
• Horticulture is the main pathway for plants. “For invasive alien plants, the horticultural trade is the primary invasion pathway” (Reichard and White, 2001; Dehnen-Schmutz et al., 2007; Drew et al., 2010) (p. 498).
• Voluntary codes exist for the US (Fay et al., 2001) and Europe (Heywood and Brunel, 2009). “Such approaches have so far had limited effectiveness and buy-in (Drew et al., 2010), although 12 European countries report initiatives related to the implementation of a code of conduct”. Effectiveness “depends largely on how well they are promoted”, which requires “continuing communication and dialogue” (p. 498).
• Industry in drafting. The International Association of Horticulture Producers (AIPH) helped draft the European code. “For the specific case of invasive alien plants, the industry cannot be seen as preventing legislation from happening, and although playing its role in challenging the issue, it has been collaborative in considering that if some species present a problem, then some alternative can be found” (p. 498). [My reading, not the chapter’s wording: a substitution logic, in which an industry accepts restrictions more readily when substitutes exist. The chapter asserts this for horticulture only, without a source.]
• Plant health pathways. “a species-by-species regulatory approach relying on inspections is more and more difficult in today’s markets context”. Forest entomology and pathology communities recommend a pathway approach for nursery stock, like the one for wood packaging, on the principle that “best management practices that effectively prevent known IAS will significantly reduce the risk of also introducing unknown pests”. The IPPC is developing a standard for plants for planting (pp. 498–499).
• Other codes: botanic gardens, the pet industry, hunting, recreational fishing, zoos and aquaria, aquaculture, ballast water, commercial forestry (p. 499).

“Stakeholders: what forces lie behind action and inaction?” (p. 499). - Scientists “have been active in communicating the dangers … although not necessarily in the most coherent way, as most scientists are not trained in public relations or communication”. - Dissent. “Dissenting views have probably had little influence on government decisions on IAS, where the consensus is now that this is a serious problem requiring some degree of attention.” This is an unsupported judgement. - Watchful interests. “Other interest groups have been silently watching the growing interest in IAS with much attention and a degree of reluctance.” These are animal welfare activists and “industries and lobbying groups, for whom restrictions on the trade of some species would hinder or complicate business”. - Horticulture’s self-image. Horticulture “would have to change its current practices substantially if serious measures to avoid new introductions were put in place. But as they feel that their industry is part of the environment business, they do not want to be seen as environmentally unfriendly.” - Others that may resist: foresters, the pet trade, aquaculture, recreational fishing and, “to a lesser extent”, hunters, zoos, aquaria and botanic gardens. “Many of these groups are generally aware of the problem and display in general a cooperative attitude … but prefer a voluntary approach with agreed codes of conduct to hard laws.” - Industry is divided. “While few businesses are in favour of more bureaucracy, some think they might be at a disadvantage compared with those who decide not to apply codes and therefore that legislation would be fairer.” - The pet industry favours voluntarism, helped draft the European Code on Pets, and “would certainly not welcome some mandatory regulations, for instance any relating to the shipping of all pets, as these would increase costs”. - Shared responsibility. “Yet it is clear that responsibility for the introduction of many invasive species lies partly with the industry and its activities, although it is also a consequence of the slowness of governments to take action or introduce legislation.”

20.10 Lessons learnt on invasive alien species: towards more transdisciplinarity in a rapidly changing world? (pp. 499–502)#

• Opening. Awareness and understanding have grown greatly, and “we need to learn lessons from this large body of experience so as to avoid further losses” (p. 499).
• An unsettled network. A large network has assembled over 30 years: researchers, agencies, NGOs, civil servants, park managers, activists, volunteers, citizens. “The ‘game rules’ for interactions between different parties are still being defined, tested, and debated. Governments and institutions charged with making decisions have access to considerable knowledge on the topic, but the lack of rules of interactions between multiple parties regularly thwarts effective decision-making” (p. 499).
• Governance must come first. “Governance of IAS needs to be achieved before the introduction of species, which means dealing with uncertainties and setting a level of protection.” “Some of these lessons are late ones (EEA, 2001)” (p. 499).

The explicit lessons, in order:

1. “Align concepts for a better understanding by society and public engagement” (pp. 499–500). - “Public understanding of the threats posed by IAS is fundamental for effective governance.” - Expert divergence “may weaken public confidence in the advice of ‘experts’. Rather than talking with one voice to the public and insisting on convergent opinions, it is more important to ensure that different opinions are made clearly understandable and transparent to the public and decision makers” (p. 499). - The historical framing “assumed that the problem could be solved by identifying the biological traits of potentially invasive species and preventing their introduction”. “Fifty years of research have shown that the identity (alien or native) and traits of the species are indeed highly relevant, but … other factors are also involved (e.g. propagule pressure, habitat factors, land use).” - Invasions correlate strongly with economic factors. On oceanic islands, “economic development (measured as gross domestic product) is the most important predictor of invasive species richness” (Kueffer et al., 2010). So “public engagement is vital” (p. 500).
2. “Harmonise concepts for improved coordination of on-the-ground actions” (p. 500). - The lack of common definitions “has led to serious problems in obtaining reliable information … and has undoubtedly hampered the development of detailed databases”. Some countries lack lists, and some “do not appear to be aware of the extent or seriousness of biological invasions”. Lists need regular updates, “requiring budgets and trained staff”. - Science and management need better links: “Initially, most research questions were disconnected from management concerns.” Impacts were considered without clarifying the human and economic context, and “it was often assumed that any detectable effect of an alien species on an ecosystem would be undesirable”. “Researching global concepts may have hindered the provision of concrete and simple actions.” - The field has since become more interdisciplinary, and cost–benefit valuation is now a research focus. “the problem of IAS, initially recognised and brought forward by scientists, is now being more firmly rooted in civil society (e.g. NGO groups).”
3. “A late lesson not yet learnt: take account of wider social interests and values” (p. 500). - This is Volume 1’s lesson, which “has been overlooked when dealing with IAS”. - More social research is needed “to eventually adapt the concepts and reconcile diverging opinions between experts and stakeholders”. - “the alien origin of a species is of minor importance for stakeholders, while the role that humans play in the spread of a species, its aesthetic and cultural value, or personal experiences with the impacts and management … are of high importance” (Bardsley and Edwards-Jones, 2007; Bremner and Park, 2007; Gobster, 2011; Selge et al., 2012). - “Additional care and thought must also be given to the language used.” - Involve “all stakeholders, including those who introduce species and members of the public who have divergent ideas”. Pathway regulation “demands ongoing dialogue with stakeholders … which, to be effective, should be undertaken at an early stage”. Attitudes of groups “such as animal rights groups” need study.
4. “Another late lesson: avoid paralysis by analysis” (pp. 500–501). - Protocols for pest risk analysis and cost–benefit study have become more consistent and transparent (the EU PRATIQUE project; EPPO, 2011), “increasingly sophisticated and multidisciplinary” (Hulme, 2011a). - “However, despite the significant advances in predicting the risks related to species introductions, the complexity of the relationships between the many potential explanatory variables still limits the precision of current risk assessment tools” (Hulme, 2011b). - Biosecurity must address a changing world. A footnote (p. 501 fn 13) quotes the FAO definition of biosecurity as “a strategic and integrated approach” covering food safety, animal and plant life and health, and “the introduction and release of genetically modified organisms (GMOs) and their products” as well as IAS. This places IAS in the same risk-governance frame as another Volume 2 topic. The lesson is then routed to Box 20.4. - The text under this heading does not itself argue the paralysis point. It describes better but imprecise risk analysis. The implied argument is that imprecision should not delay action.
5. Box 20.4, “A lesson for Europe: do not take the need for European coordination as an excuse for inaction” (p. 501). - “A particular problem for Europe has been the long time taken by European institutions to propose coordinated stringent measures”. A dedicated instrument is “likely” before 2013, “but 2013 is twenty years after scientists alerted governments to the dimension of the problem … During that time the problem has grown worse.” - “Many governments were reluctant to pass legislation on the grounds that the free movement of goods in the EU did not permit them to restrict the import of alien species … This remains a doubtful claim, as a few European governments did not hesitate to take that step.” - Because environment is an EU competence and resources are scarce, “some EU states … pay a greater attention to the legal requirement for implementation of EU legal instruments and tend to pay less attention to other issues not specifically covered by European legislation, including much-needed action on IAS”. - The Habitats Directive (1992) contains obligations, and the Commission has funded research, data and eradication since the late 1990s. But “government awareness of the need for a more stringent legislative instrument has only come since the growing economic and environmental costs of invasive species have become difficult to ignore”. - “The problem is complex, awareness only relatively recent, government interest limited, and public resources scarce. Hard times for native species!”
6. “Anticipate further challenges and ‘blind spots’ in a changing world” (p. 501). - Invasions are “a complex societal issue because knowledge is highly uncertain, and because conflicts of interest and values are central to the problem” (Kueffer and Hirsch Hadorn, 2008). - More debate is expected over biofuel crops and managed relocation. Global change amplifies contextual factors, so current criteria for invasiveness “are likely to be increasingly challenged”. - Example: future montane invaders “may be mountain specialists directly introduced through human activity between high-elevation habitats, rather than … climatically plastic species that spread from lowlands” (McDougall et al., 2011).
7. “Do not allow philosophical debates to create blockages in tackling the problem” (p. 502). - Invasions sit “between ‘nature’ and ‘culture’”. “issues related to IAS are ‘nature threatening nature’ through human activities, making the role of humans difficult to unravel”, especially in Europe, where ecosystems have been modified “since prehistoric times”. - “Such uneasiness sends us back to the classical argument ‘it is natural therefore it is safe’.” - Global change “will increasingly challenge current assumptions”. “The risk of invasion should be perceived not only as coming from alien species, but rather as a socio-ecological phenomenon” (Kueffer, 2010). The response must combine the human dimension “with the urgent need to respond”.

Table 20.1, “Early warnings and actions” (p. 502)#

Checked visually. Entries:

Apart from Pliny’s “very severe problem” with rabbits, the table contains no specific harms, no costs, no regulatory failures and nothing after the 2000s. It records how knowledge and institutions grew, not how warnings were received. The EU legislative lag, the chapter’s main “late lesson”, is not in the table.

References (pp. 503–508)#

• About 120 entries.
• Heavy self-citation: about 35 authored or co-authored by the chapter authors, plus ISSG (2011); see “Authors and standpoint”.
• Minor errors:
• Kueffer and Hirsch Hadorn (2008) is listed twice;
• “Simberloff and 141 scientists” is dated 2001 in the text but 2011 in the references;
• “Clavero and Garcia-Barthou” in the text but “Garcia-Berthou” in the references;
• the garbled “Consulting et al., 2010” in Box 20.2;
• a few entries are never cited in the text, e.g. Alyokhin 2011, Lerdau and Wickham 2011 (both Nature correspondence in the same issue as “Simberloff and 141 scientists”, apparently replying to Davis et al.), Morse et al. 1995, Weidema 2000, Kueffer and Daehler 2008, Simberloff et al. 2011;
• conversely, several works cited in the text are missing from the list: Lambdon et al. 2008 (pp. 487–488), Hooker 1864 (p. 489), McLachlan et al. 2007, Hunter 2007 and Hoegh-Guldberg et al. 2008 (p. 495).
• Grey literature. Much of the policy evidence is grey literature: the Bern Convention Standing Committee report, IEEP and consultancy reports for the Commission, the ISSG website statement, a CABI web page and a French Senate question.

How the rest of the report uses this chapter#

• Introduction, p. 9. One reason for Volume 2 is “to address the rapid emergence of new society-wide challenges such as radiation from mobile phones, genetically-modified products, nanotechnologies and invasive alien species”.
• Introduction, p. 10. Part C covers “newly emerging and large-scale products, technologies and trends”, including “the growing threat of invasive alien species”. “There is often little science, and very little direct hindsight, to assist in the management of these emerging technologies.”
• Ch. 27 (Gee), p. 644. “The chapters on alien species, floods, and ecosystems … also provide insights into how the management of ecosystems could develop.”
• Ch. 27, p. 651. Chapter 20 is one of four chapters illustrating “complex and multi-causal factors” in ecological systems.
• Ch. 27, Table 27.1, p. 656. The report’s typology of knowledge uses IAS as the example of ambiguity, meaning “different values and interpretations about information used by stakeholders. E.g. in invasive alien species cases where a species can be welcomed by some but not others”. The matching action is “Participatory precaution: stakeholder engagement”.
• Ch. 28, pp. 674–676. IAS are listed as a co-stressor on ecosystems (p. 674). They are also grouped with GM crops, mobile phones and nanotechnology as “such emerging technologies” where the science is “relatively immature” (p. 675). And they are named as a field with “much reliance on modelling” where recognising uncertainty and ignorance matters (p. 676).
• Ch. 25, p. 609 cites “mobile phones (Chapter 20)”. This is a numbering error, not a reference to this chapter: the same sentence is off by one throughout (mobile phones is Ch. 21, GMOs Ch. 19 not 18, nanotechnology Ch. 22 not 21, per the table of contents).
• Assessment. The synthesis takes from this chapter mainly the ambiguity/participatory point and the complexity point. It does not take up its governance-specific lessons: lag and liability, regulatory asymmetry, the single-market excuse. Calling IAS an “emerging technology” (p. 675) stretches the category. What is “emerging” is a hazard produced by trade and travel.

Case timeline#

This is a review chapter, not a single case. Below are (a) the field-level timeline and (b) the mini-cases, with what the chapter says about warning, response and lag.

(a) Field level: recognition and institutional response#

Lag. - By the chapter’s own measure (Box 20.4), about 20 years from scientists alerting governments (around 1993) to a dedicated EU instrument, which was still only expected when the chapter went to press. - From Elton (1958), about 55 years. - During the lag, “the problem has grown worse” (p. 501), and invasions show “no indication yet of any saturation effect” (p. 493). - [Background, unverified: the Commission proposal came in September 2013, and Regulation (EU) No 1143/2014 applied from 1 January 2015, with the first “Union list” adopted in 2016. That would put the lag at about 21–23 years. Check against EUR-Lex.]

(b) Mini-cases#

What was known when. - The generic warning (Elton 1958; SCOPE 1980s; CBD 1993) was strong and global long before EU action. The chapter’s framing implies the core knowledge needed to act (prevention, early eradication, pathway control) was available by the 1990s–2000s. It says the Bern Strategy (2003) and Commission documents (2011) “contain sufficient guidance for precise government action” (p. 492). - What was not known, and still isn’t, is which species will become invasive, where and when (pp. 487, 490, 501). The chapter’s case for precaution rests on that irreducible uncertainty, combined with the steep cost of delay.

The authors’ own lessons and conclusions#

As stated (Section 20.10 and Box 20.4)#

1. Align concepts for public understanding and engagement. Make divergent expert views “clearly understandable and transparent” rather than “talking with one voice” (p. 499). Human activity drives invasions, so “public engagement is vital” (p. 500).
2. Harmonise concepts and definitions to get reliable data, lists and databases. Fund list upkeep (“budgets and trained staff”). Connect science to management; the chapter notes, hedged, that “Researching global concepts may have hindered the provision of concrete and simple actions” (p. 500).
3. Take account of wider social interests and values, called “a late lesson not yet learnt” and taken from Volume 1. That means social research on perceptions, care with language, involving all stakeholders including introducers, and early dialogue (p. 500).
4. Avoid paralysis by analysis. Risk assessment has improved but remains imprecise (pp. 500–501). “So do not wait for precision” is the implied point; the text under the heading does not state it.
5. Do not use the need for European coordination as an excuse for inaction. National action is possible; the free-movement objection is “a doubtful claim” (Box 20.4, p. 501).
6. Anticipate further challenges and “blind spots” in a changing world: biofuel crops, managed relocation, novel ecosystems, changing invasion patterns (p. 501).
7. Do not allow philosophical debates about nature and culture, or native and alien, “to create blockages”. Treat invasion as a “socio-ecological phenomenon” (p. 502).

Conclusions stated elsewhere#

• Prevention or very early action is the most cost-effective approach (pp. 486, 487). Precaution is needed because a prompt response cannot wait for full risk assessment (p. 487).
• Even good risk assessment will miss things, so early warning and rapid eradication systems are needed (pp. 486, 497).
• Where to draw the risk line is a value judgement for governments, informed by societal debate (pp. 486, 497).
• Legislative and voluntary approaches are both needed, “the one reinforcing the other” (p. 497).
• Pathway-based regulation is replacing species-by-species regulation (pp. 498–499).
• A pragmatic mix: prevention, early detection, rapid response, with permanent management last (p. 494).
• Rigid “guilty until proven innocent” precaution is problematic under free trade (p. 497).

Derived from evidence versus advocacy#

• Best grounded in the chapter’s evidence:
• the limits of trait-based prediction (p. 490);
• the phase model and the lag phase (pp. 490, 497);
• the value of early eradication (pp. 487, 491, 498);
• fragmented EU law (Box 20.1);
• continued legal sale of species under control (p. 492);
• the dominance of horticulture as a pathway (p. 498);
• stakeholders’ values differing from experts’ (p. 500, four studies cited).
• Advocacy, or asserted from experience:
• the “doubtful claim” about free movement (p. 501, not legally argued);
• the characterisation of industry attitudes (p. 499, no sources);
• “Dissenting views have probably had little influence” (p. 499);
• that philosophical debate is “blocking” (p. 502);
• “avoid paralysis by analysis” (p. 500), whose heading goes further than its text;
• the cost-effectiveness claim (p. 494, which the chapter itself qualifies with “according to this perspective”).
• Institutional self-positioning. The lessons are mostly about how the IAS community should communicate and coordinate, and how governments should stop stalling. Almost none address whether the community’s own risk judgements could be wrong, apart from the historical admission that early research treated any detectable effect as harm (p. 500). The body of the chapter is somewhat more candid than the lessons: it admits misidentification that wastes resources (p. 488), biocontrol introductions whose impacts “had not been assessed accurately” (p. 496), and the need to use the best predictor “with great caution” (p. 490).

Mechanisms and dynamics#

How warnings arose and were contested#

• Warnings came from science, not from victims. The problem “initially recognised and brought forward by scientists” moved into civil society only later (p. 500). The chapter describes no organised community of injured parties pressing for action (my observation). Harms fall on biodiversity, on fisheries (signal crayfish), on agriculture and health (ragweed), and on those who pay for control.
• Distance as a filter. European scientists and conservationists saw invasions as “somewhere else” until the 1980s–90s (p. 489). A hazard seen as belonging to other places or other ecosystems delays domestic recognition.
• Contestation inside science.
• Critics: Sagoff (2005); Davis et al. (2011).
• Defenders: Simberloff (2005); ISSG (2011); “Simberloff and 141 scientists”.
• What is contested: how common harmful invasions are, whether alien origin is a good heuristic, and what strict prevention costs in lost opportunities (p. 494).
• Critique from social science: Larson (2007) and Warren (2007) on “xenophobic” framing (pp. 494–495).
• The chapter treats this contest as a mix of legitimate debate and a drag on action (pp. 493, 502).
• Definitions shape evidence. The impact-based definition (mostly policy) and the spread-based definition (mostly academia) coexist, and lists built on different criteria are hard to aggregate or compare (pp. 487–488, 500); the chapter says such problems “contributed to” the incoherent political response (p. 488). The category is “a hybrid” of biology and human perceptions (p. 494). So what counts as evidence of harm depends on values as well as observation. This is why Ch. 27 uses IAS as its example of ambiguity (p. 656).

Uncertainty, prediction and time#

• Irreducible predictive uncertainty. No common trait list separates invaders from non-invaders (p. 490), although traits remain “highly relevant” (p. 500). The best predictor, invasiveness elsewhere, degrades under global change (pp. 490, 501). Complexity “still limits the precision” of risk tools (p. 501). Impacts are context-dependent, as with cinnamon in the Seychelles (p. 494).
• Lag phase. Species may be unnoticed “for several decades” before becoming invasive (p. 497), and invasiveness may appear “decades after” introduction (p. 494). Three consequences:
• the decision point comes long before the evidence (p. 497);
• liability fails because traceability is lost (p. 497);
• mediation between interests has nothing firm to mediate over (p. 497).
• Closing windows. Eradication costs rise at least 40-fold with delay (p. 487), and eradication “quickly becomes unfeasible” (p. 487). The paired Caulerpa cases (France 1984 versus California 2000) show the window (p. 498). This time structure is why the chapter defines precaution partly as speed: act before full assessment (p. 487; “eradicate new invaders in a timely manner”, p. 498).
• Irreversibility. Signal crayfish are “now out of control” (p. 497). Caulerpa eradication was “no longer possible” (p. 498). Grey squirrels are expected to spread across Europe (p. 495). Once past establishment and spread, a hazard can usually only be managed permanently.

Burden and standard of proof#

• Three positions (pp. 494, 497–498):
• “guilty until proven innocent”, the research default and the New Zealand white list;
• regulation only of listed “unwanted” species (black list, IPPC);
• the Davis et al. critique that requiring species to be “proved innocuous” wastes conservation money.
• Trade law constrains the stricter model: rigid precaution is “problematic in the context of free-trade agreements” (p. 497).
• Asymmetric burden between remedy and hazard. Releasing a biocontrol agent faces “quite stringent” EU legislation, while “legislation against the introduction of any other species, including acknowledged invasive ones is non-existent” (p. 496). The deliberate countermeasure carries a heavier burden of proof than the commerce that creates the hazard. In the Spanish water hyacinth case this blocked a remedy proven elsewhere (p. 496).

Law, institutions and governance#

• Fragmented mandates. Environment and agriculture ministries (plus health, transport and others) share responsibility, and national mandates are “not always clear” (p. 491). The older plant and animal health regime came first and frames the problem around agricultural pests (p. 491). Ragweed shows turf disputes delaying action (pp. 496–497).
• Treaty proliferation without teeth. More than 42 treaties refer to IAS (pp. 491, 493), but the core European instruments are vague and discretionary (Box 20.1, p. 492). Strategies are “not legally-binding” and applied “patchily” (p. 492).
• Multi-level governance and deferral. Trade regulation is an EU competence, so national measures have “limited effectiveness” (p. 492). Governments cited free movement to justify inaction, which the chapter calls “a doubtful claim” (p. 501). “Some EU states” prioritise what EU law requires and “tend to pay less attention” to what it doesn’t (p. 501). Compliance-driven prioritisation: institutions under resource pressure put what is legally required first and let other issues slide.
• Awareness follows cost. Stricter EU measures “may also have been helped” by the EUR 12.5bn cost estimate (p. 491). Government awareness came only when costs became “difficult to ignore” (p. 501).
• Voluntarism as the default. Voluntary codes “by definition lack sanctions” (p. 493) and have “limited effectiveness and buy-in” (p. 498), yet most industries prefer them (p. 499). The chapter’s own position is that both are needed (p. 497).
• Courts as veto points. In Italy a prosecution under animal-cruelty law stopped a time-critical eradication (p. 495). Legal instruments built for one value (animal welfare) can defeat action taken for another (biodiversity).
• Fragile knowledge infrastructure. GISP closed “for financial reasons” (p. 489). Lists need continuing budgets and staff (p. 500).

Interests, economics and trade#

• Who gains and who bears the harm.
• Gains: sellers of ornamental plants and pets, crayfish breeders, some agricultural and biofuel interests, and users of introduced species generally (pp. 497, 499, 495).
• Harms: native biodiversity; control and damage costs (18 million euros for water hyacinth in Spain; more than GBP 150m a year to manage Japanese knotweed in the UK; economic costs over EUR 12.5bn a year in Europe) (pp. 492, 496, 491), much of which falls on public authorities, though the chapter does not break down who pays; farmers and allergy sufferers (ragweed, pp. 496–497); Scandinavian crayfish fisheries (p. 497); and Spain’s conservation effort for white-headed duck, threatened by a UK escapee (p. 495).
• [My inference, not stated in the chapter:] the benefits tend to be private and concentrated, while the costs are largely public, spread out and sometimes fall in other jurisdictions (ruddy duck; the water hyacinth UK/Mediterranean question).
• Spatial externalities in a single market. A species harmless in the UK but invasive in the Mediterranean poses a question: whose interests set the rule? (p. 497). The jurisdiction that benefits from allowing a species need not be the one harmed. Ruddy duck shows the same thing across a border: a UK escapee harmed a Spanish conservation priority, and the fix had to be made in the UK (p. 495).
• Economic activity drives the hazard. Invasions correlate with economic factors, and GDP is the top predictor of invasive species richness on islands (p. 500). The hazard is a by-product of the volume of trade and travel, not of any single decision.
• Industry identity and strategy.
• Horticulture sees itself as “part of the environment business” and does not want to look unfriendly, but would need to change practice substantially (p. 499).
• Horticulture has been “collaborative” on the basis that “some alternative can be found” (p. 498); the chapter asserts this for one industry only.
• Some firms favour legislation to avoid being undercut by non-compliers (p. 499).
• The pet industry resists mandatory shipping rules on cost grounds (p. 499).
• Groups “silently watching … with a degree of reluctance” (p. 499) suggest latent opposition that is likely to surface when rules threaten business (my reading).
• Lock-in through beneficiaries. Once an introduced species has users, such as crayfish breeders (p. 497) or the pet shops still selling grey squirrels (p. 492), control is contested and trade continues even while public money is spent on containment.

Technological fixes that become hazards#

• Signal crayfish was brought in to fix a disease problem in native crayfish fisheries. It carried the disease and became invasive (p. 497).
• Cane toad was introduced as pest control and became a pest (p. 496).
• Cactoblastis succeeded where intended, but its later accidental spread harmed non-target native cacti (p. 496).
• The chapter’s diagnosis each time is inadequate assessment (“had not been assessed accurately”, p. 496). It is confident that modern protocols “greatly reduce the chance of unexpected behaviour” (p. 496). This sits uneasily with its own statement that complexity limits the precision of risk tools (p. 501).
• Precaution about fixes creates a second-order dilemma. Public memory of failed fixes (“a typical example that is used to oppose biological control”, p. 496) creates resistance to later, better-assessed fixes. The chapter argues that this caution “prevents this efficient technique from being used when IAS are widespread” (p. 496). This is a risk–risk trade-off: precaution applied to the remedy prolongs exposure to the original harm.

Public values, emotion and framing#

• Charisma and welfare. “Too cute to be killed” (Box 20.2 title). Lethal control of attractive animals meets outcry and legal challenge (p. 495). Herbicide use meets opposition from people who see chemicals as worse than the invasion (p. 494).
• Intermediaries. The RSPB’s endorsement “was decisive in getting the project started” and cost the society members (p. 495). A trusted civil-society body can unlock contested action, but pays for it.
• Trust. “Often scientists are not fully trusted either” (p. 496). The chapter also worries that visible expert disagreement “may weaken public confidence” (p. 499).
• Language.
• “Alien” and “invasive” carry “political overtones” (p. 487).
• “Black lists” were renamed because the term was “not considered politically correct” (p. 498 fn 10).
• The press uses “the yellow peril” (p. 495).
• Critics call conservationists “xenophobic” (p. 495).
• The chapter’s own vocabulary is also loaded: “invaders in disguise” (p. 488), “the struggle against invasions” (p. 495), “courageous decision” (p. 495), “Hard times for native species!” (p. 501).
• The authors call for “care and thought” with language (p. 500). They apply it selectively: they avoid “black list” (p. 498 fn 10) but keep the militarised and moralised terms above.
• “It is natural therefore it is safe” (p. 502). The authors identify a cognitive shortcut: because IAS are “nature threatening nature”, the human cause is hard to see, and living things are presumed benign. The reverse shortcut (“alien” means dangerous) is what the social-science critics identify (pp. 494–495) and what the chapter says distorts public views of biocontrol (“negative feelings towards alien species”, p. 496). The chapter recognises both shortcuts.
• Stakeholder valuation differs from expert valuation. For stakeholders, alien origin is “of minor importance”. The human role, aesthetic and cultural value, and personal experience matter more (p. 500).

Mental models of the actors (as the chapter portrays them)#

• Early invasion scientists:
• trait-based prediction would solve the problem (p. 500);
• alien origin explains behaviour (p. 490);
• any detectable effect is harm (p. 500);
• research on global concepts was pursued at some cost to “concrete and simple actions” (p. 500, hedged “may have hindered”).
• Blind spots: landscape and land use (pp. 490–491), economics and human pathways (p. 490), social values (p. 500).
• For many European “biologists and conservationists”, invasions happened “somewhere else” (p. 489).
• Current invasion scientists (the authors’ community). Prevention is justified “irrespective of how common problematic invasions” are, because of the size of the ones that happen (p. 494). Dissent is a periodic challenge to a settled consensus (pp. 493, 499). Scientists are sincere but poor communicators (p. 499).
• Governments and regulators:
• pest and agriculture framing predates the biodiversity framing (p. 491);
• defer to the EU (p. 501);
• do what EU law mandates (p. 501);
• act once costs are undeniable (p. 501);
• be strict with deliberate releases of biocontrol agents and lax on trade in known invasives (p. 496).
• Industry: part of the green economy (p. 499); prefers voluntary codes; open to substitution; divided on whether regulation is fair (pp. 498–499).
• Public: protective of charismatic animals (p. 495); suspicious of chemicals and of introducing more “aliens” as controls (pp. 494, 496); partly responsible for spread (p. 497).

Innovation dynamics#

• New introductions as innovation risk. Novel crops for biofuel and biomass, managed relocation or assisted colonisation, and synthetic biology are named as future sources of invasions (pp. 495, 501).
• Regulatory innovation.
• A shift from species-by-species inspection to pathway regulation (pp. 498–499), modelled on the wood-packaging precedent. The principle: good practice against known pests reduces the risk of unknown ones.
• Risk-assessment innovation: weed risk assessment (Pheloung et al., 1999), PRATIQUE, EFSA scenario approaches (pp. 490, 498, 500–501).
• Innovation blocked by regulation. Stringent biocontrol rules block a proven method (p. 496). The first European release against an invasive plant came only after years of testing (p. 496).

Complexity and systems#

• Invasions are a “socio-ecological phenomenon” (p. 502) arising from biological and social factors that “interact in complex ways” (p. 491). Propagule pressure, habitat, land use and economics matter alongside species traits (p. 500).
• Global change reshapes the problem: novel ecosystems, shifting montane invaders, altered climatic suitability (pp. 495, 501). The chapter expects its own “criteria currently used” to be “increasingly challenged” (p. 501).
• Ch. 27 draws on the chapter as an example of multi-causal complexity (p. 651).

Transferable insights (technology-neutral)#

1. Latency erodes accountability and forces decisions ahead of evidence. When harm can appear decades after release, the origin becomes untraceable, liability tools fail, and negotiated settlements have nothing firm to bargain over. Decisions must be taken at the point of introduction, under uncertainty. - Evidence: lag phase and liability (p. 497); invasiveness “decades after” introduction (p. 494); “Governance … needs to be achieved before the introduction” (p. 499). - Strength: moderate. The lag phase is well established in the field. The liability argument is reasoned rather than shown with cases.
2. The window for effective intervention closes fast and the cost of delay is non-linear. Precaution can mean speed of response, not only prior restriction. - Evidence: eradication cost up at least 40-fold with delay (p. 487); eradication “quickly becomes unfeasible” (p. 487); Caulerpa, France 1984 against California 2000 (p. 498); more than 1,100 eradications and 17 species with improved status (p. 491). - Strength: moderate. One quantitative estimate (Harris and Timmins, 2009, a single-country study [background]) and one paired comparison that differs in jurisdiction and period. The general pattern is widely accepted in the field.
3. How a harm category is defined drives what data exist and whether policy can cohere. A behaviour-based definition and an impact-based one, used side by side, yield lists, statistics and arguments that are hard to compare or aggregate. Headline numbers can mislead when the category mixes benign and harmful members. - Evidence: academic versus policy definitions (p. 488); counts of 9–222 across 57 countries (p. 488); Pimentel’s 50,000 “misleading unless broken down” (p. 488); databases hampered (p. 500). - Strength: moderate. Good illustrations. The causal claim (“contributed to difficulties”, p. 488) is plausible but asserted.
4. Hazards that straddle institutional mandates fall into jurisdictional gaps, and turf disputes delay action. - Evidence: unclear environment and agriculture mandates (p. 491); ragweed, health against agriculture (pp. 496–497); frameworks to align at EU level (p. 496). - Strength: suggestive. A clear mechanism, but one example without dates or measured delay.
5. Waiting for higher-level coordination can become a rationale for doing nothing, and institutions under resource pressure prioritise what is legally mandated. - Evidence: Box 20.4 (p. 501); some states did act, including Norway, Switzerland 2008 and Spain 2011 (p. 492); the roughly 20-year gap (p. 501). - Strength: moderate. The national counterexamples show action was possible. The “doubtful claim” judgement about legal constraints is asserted, not argued.
6. Regulatory asymmetry: deliberate countermeasures can face stricter rules than the activity causing the harm, which inverts protection. - Evidence: stringent EU rules on biocontrol releases, none on known invasives (p. 496); water hyacinth biocontrol ruled out (p. 496). - Strength: suggestive. One clear case plus a structural description of the rules.
7. Commerce in a hazardous item can continue while public money is spent containing it. Private benefit and public cost run in parallel. - Evidence: water hyacinth still traded after 18 million euros of control (p. 492); grey squirrels on sale 12 years after an international request to ban trade (p. 492). - Strength: moderate. Two concrete, documented examples. How typical they are is not shown.
8. Incumbents prefer voluntary codes. Voluntary codes without sanctions have limited effect. Some firms favour binding rules to avoid being undercut by non-compliers. - Evidence: pp. 493, 498 (Drew et al., 2010; 12 countries with initiatives), 499. - Strength: moderate on limited effectiveness (a cited study); asserted on the industry preferences, which come from the authors’ experience without sources.
9. Availability of substitutes lowers resistance to restriction. - Evidence: horticulture “collaborative in considering that if some species present a problem, then some alternative can be found” (p. 498). - Strength: suggestive. A single assertion about one industry.
10. A fix introduced into a complex system can become the next hazard, and once it has beneficiaries, reversing it is contested.
    • Evidence: signal crayfish, a remedy that carried the disease, then a breeders-versus-controllers conflict (p. 497); cane toad and Cactoblastis (p. 496).
    • Strength: moderate. Well-known cases, though the chapter’s treatment is brief and undated.
11. Past failures of interventions shape later trust, so precaution about the remedy can prolong the original harm (a risk–risk trade-off).
    • Evidence: Cactoblastis used to oppose biocontrol; public and decision-maker reluctance; “scientists are not fully trusted” (p. 496); the Réunion false alarm resolved by study and dialogue (p. 496).
    • Strength: suggestive. Illustrative cases chosen by authors who favour the intervention.
12. Prediction from intrinsic properties alone is insufficient for complex-system hazards; context and exposure matter too. Track record elsewhere is the best single predictor, and it degrades as conditions change.
    • Evidence: no common trait list after decades (p. 490), though traits remain “highly relevant” alongside propagule pressure, habitat and land use (p. 500); invasiveness elsewhere as best predictor, with caution under global change (pp. 490, 501); complexity limits risk-tool precision (p. 501).
    • Strength: strong within the domain, as the chapter’s summary of a large research programme (asserted with citations rather than shown in detail). Its transfer to other domains is by analogy.
13. Harm scales with the volume and structure of human activity (exposure pathways), not only with properties of the agent. That favours regulating pathways over item-by-item inspection.
    • Evidence: “human-driven” (p. 487); GDP the top predictor of island invasions (p. 500); propagule pressure and land use (p. 500); horticulture the primary pathway (p. 498); the pathway approach for plant health (pp. 498–499).
    • Strength: moderate–strong. Several cited quantitative studies. The pathway-regulation benefit is argued by analogy with wood packaging, not shown.
14. Emotional salience and competing values determine which interventions are feasible. A single legal challenge can derail time-critical action. Endorsement by a trusted intermediary can unlock action at a cost to that intermediary.
    • Evidence: Box 20.2 (p. 495); herbicide opposition (p. 494).
    • Strength: moderate. Two well-described cases, told by participants on one side.
15. Stakeholders judge hazards on different criteria from experts, such as the human role, aesthetics and personal experience, so expert categories do not persuade on their own.
    • Evidence: p. 500, four social studies cited.
    • Strength: moderate.
16. Political attention tends to follow monetised cost estimates, not ecological evidence alone.
    • Evidence: the EUR 12.5bn estimate “may also have” helped (p. 491); awareness only when costs became “difficult to ignore” (p. 501).
    • Strength: suggestive. The chapter hedges the causal claim itself.
17. Hazards seen as belonging “somewhere else” are recognised late at home.
    • Evidence: p. 489.
    • Strength: suggestive. One sentence, no evidence of who held the view.
18. The expert community faces a tension between transparent disagreement and fear that visible disagreement will stall action.
    • Evidence: “different opinions … transparent” (p. 499) against “too much focus on these controversies can have a deleterious effect” (p. 493) and “Do not allow philosophical debates to create blockages” (p. 502).
    • Strength: asserted. The tension is visible in the text but not resolved or tested.
19. The knowledge infrastructure for detecting and tracking a diffuse hazard is fragile and depends on continuing funding.
    • Evidence: GISP closed for financial reasons (p. 489); lists need “budgets and trained staff” (p. 500).
    • Strength: suggestive.
20. Where to set the acceptable level of risk is a value judgement that needs public deliberation, which in turn needs public understanding. The jurisdiction that benefits may not be the one harmed.
    • Evidence: p. 497, including the water hyacinth case and the UK/Mediterranean split.
    • Strength: asserted as a normative claim. The spatial-externality example is concrete.
21. Detection depends on correct classification, and misclassification cuts both ways: benign items treated as hazards waste resources, and hazards that look benign escape action.
    • Evidence: “harmless species can be confused with harmful invasive species, leading to a waste of resources”, and “invaders in disguise” (Verloove, 2010) (pp. 486, 488); frequent confusion of well-known invaders and expert disagreement over species limits (p. 488).
    • Strength: suggestive. Named examples of confusion, but no measure of how often either error happens or what it costs.

Limitations, contestation and bias check#

Advocacy by participants, with undisclosed roles. - The authors lead or work in key institutions in the story (in charge of the Bern Convention; chair of the ISSG; a scientific officer at EPPO) and wrote several of the instruments and studies cited as examples (the European Strategy on IAS, the horticulture code, the Kettunen cost study, the account of the Italian grey squirrel attempt). About 30% of references are their own work (my count: about 36 of 122 entries). - The chapter does not tell readers this. Annex 1 does. - This does not make the account wrong, but it shapes the story: the Bern Convention appears as a consistent good actor; the ISSG answers the critics; the institutional and policy failures shown are other people’s (the Italian government, the courts, EU institutions, member states, industry). The self-criticism that is present concerns the research field’s concepts, early framing and communication (pp. 490, 499–500), not decisions taken by the authors’ own institutions.

No panel or counter-voice. Unlike several Volume 2 chapters, there is no commentary from critics (Davis et al., Sagoff), from industry (AIPH, the pet trade) or from animal-welfare groups. Critics are summarised briefly (Sagoff only as a citation, p. 493; Davis et al. in two short passages, pp. 494–495; Larson and Warren in one sentence, p. 494) and are answered at greater length by the ISSG (p. 494) and “Simberloff and 141 scientists” (p. 495).

Opportunity costs not really answered. Davis et al.’s point (p. 494) is about the opportunity cost of strict prevention. The ISSG reply (“irrespective of how common … prevention is needed because of the huge impacts”) restates the precautionary premise rather than engaging with the trade-off. The chapter’s own “pragmatic approach” (p. 494) quietly concedes something to the critics: prevention of the worst impacts, not of all aliens.

Cost figures used unevenly. - The chapter warns that Pimentel et al.’s 50,000-species figure is “misleading unless broken down” (p. 488). Six pages later it uses a Pimentel-attributed global cost (USD 1.4 trillion a year, “about 5 % of global GDP”) without caveat, followed by uncited national figures (USD 138 billion for the US; USD 14.45 billion for China) (p. 494). - [Background, unverified: the 1.4 trillion global figure is usually traced to Pimentel et al. 2001, and the 138 billion US figure to Pimentel et al. 2000. The 2005 paper cited gives about USD 120 billion for the US. Pimentel’s methods have been widely criticised. Check.] - The cost-of-inaction versus cost-of-action comparison (EUR 12bn against EUR 40–190m, p. 494) sets total current damage, much of it from long-established species, against the cost of new policy options. That overstates the return unless the policy would avert most of the damage. The chapter hedges (“according to this perspective”) but still draws the “very cost-effective” conclusion. The European damage figure also varies within the chapter (over EUR 12.5bn, p. 491; EUR 12bn, p. 494).

Questionable causal attribution. Box 20.1 says Europe’s roughly 11,000 alien species are there “partly as a result of the lack of coordinated action” (p. 492). [Background, unverified: many, probably most, of these species arrived before coordinated action was on anyone’s agenda (the chapter dates wide acknowledgement of the problem to the 1980s–90s, p. 489).] The chapter gives no evidence for the link, which reads as rhetorical, though it is hedged with “partly”.

Case selection is one-sided on false positives. Volume 2’s introduction promises attention to false positives (p. 9), but this chapter has none on the hazard side: no case where a species was restricted or eradicated and later shown harmless, or where eradication did more harm than good. False alarms appear only about remedies (Réunion biocontrol, p. 496). The chapter does acknowledge misidentification leading to “a waste of resources” (p. 488) and context-dependence (cinnamon, p. 494).

Hindsight. - Caulerpa: “could have been quickly removed” in 1984 (p. 498). The chapter doesn’t show that anyone then had reason to think the alga would spread; that became clear later. The comparison with California in 2000 flatters decisive action by ignoring that California had the Mediterranean experience to learn from. The chapter states the general principle that lessons learnt elsewhere should inform management (p. 487) but does not draw it from this case. - Signal crayfish: “Clearly a decision should have been taken long before” (p. 497). The chapter doesn’t say what was known about the crayfish’s disease-carrying status when it was introduced.

Thin evidence for several governance claims. - The ragweed delay (pp. 496–497) has no dates or measures. - The characterisation of industry preferences (p. 499) is unsourced. - “Dissenting views have probably had little influence” (p. 499) is speculation. - The “twenty years” in Box 20.4 is not tied to a specific warning event. - The “avoid paralysis by analysis” section (pp. 500–501) never shows a case of paralysis caused by analysis.

Internal tensions. - Confidence in risk assessment is high when it supports intervention: biocontrol protocols “greatly reduce the chance of unexpected behaviour” (p. 496). It is low when it would support permitting introductions: “complexity … still limits the precision” (p. 501). To be fair, host-specificity testing for biocontrol is a narrower prediction problem than forecasting invasiveness. The asymmetry deserves noting all the same. - Calls for transparency about disagreement (p. 499) sit alongside calls not to let debate “create blockages” (pp. 493, 502). Who decides which debates are legitimate and which are blocking is left to the authors. - The call for care with language (p. 500) is not applied to the chapter’s own militarised or moralised terms (“struggle”, “courageous”, “Hard times for native species!”).

Errors and editing slips (minor, but they indicate the level of care): - “survival of the fittest” attributed to Darwin 1859 (p. 489); - 2001 against 2011 for Simberloff et al. (p. 495); - ISSG called “first thematic” (p. 493 fn) but “first interdisciplinary” (p. 502); calling a 1993 body “one of the oldest” organisations in the field (p. 493) is odd but not necessarily wrong, given how young the institutional field is; - the dangling citation (p. 493); garbled “Consulting et al.” (p. 495); duplicated reference (p. 506); five in-text citations missing from the reference list (see References); - Caulerpa “detected in France” [background, unverified: first recorded off Monaco].

Fair in the other direction. The chapter is more self-critical than most in the collection: - it admits the field’s early blind spots (pp. 490–491, 500) and conceptual confusion (pp. 487–488, 493); - it concedes the value-laden nature of the category (p. 494) and that “rigid” precaution is problematic (p. 497); - it gives social-science critics a hearing (pp. 494–495, 500) and calls for public deliberation on proportionality (p. 497); - it credits industry cooperation (AIPH) (p. 498); - it recognises that both voluntary and legal tools are needed (p. 497).

Its main claims (invasions are a leading biodiversity driver, prevention and early response beat late control, and EU governance was slow and fragmented) were mainstream positions in the scientific literature of the time, not fringe advocacy.

Framing effects of the Late Lessons template. Being placed among “Emerging issues” and labelled an “emerging technology” (p. 675) pushes a diffuse, trade-driven hazard into a technology-risk frame. The “early warnings” table becomes a history-of-science timeline because there is no single product, proponent or regulatory decision to follow. The precaution framing fits the prevention side of the problem well. It fits the contested value questions (what counts as harm, what “natural” means) less well, and there the chapter turns to participation and communication instead.

Notable quotes#

1. “This is more a human-driven environmental problem than a strictly biological one.” (p. 487)
2. “Preventive management calls for a precautionary approach, because prompt response often does not permit full assessment of the risks connected to a newly detected invasion” (p. 487)
3. “for many biologists and conservationists, biological invasions were still perceived as happening ‘somewhere else’” (p. 489)
4. “invasions continue to grow at a rapid rate, with no indication yet of any saturation effect” (p. 493)
5. “At a European level, legislation on the introduction of biological agents is quite stringent, while legislation against the introduction of any other species, including acknowledged invasive ones is non-existent.” (p. 496)
6. “before becoming invasive, a species may remain unnoticed in an area for several decades, the so-called ‘lag phase’” (p. 497)
7. “Governance of IAS needs to be achieved before the introduction of species, which means dealing with uncertainties and setting a level of protection.” (p. 499)
8. “Rather than talking with one voice to the public and insisting on convergent opinions, it is more important to ensure that different opinions are made clearly understandable and transparent” (p. 499)
9. “2013 is twenty years after scientists alerted governments to the dimension of the problem … During that time the problem has grown worse.” (p. 501)
10. “Such uneasiness sends us back to the classical argument ‘it is natural therefore it is safe’.” (p. 502)

Open questions#

1. What was the EU’s actual response, and did it address the chapter’s diagnosis? Did it follow the black-list or white-list model (pp. 497–498)? Did it resolve the single-market proportionality problem (p. 497)? Did it close the gap between biocontrol and trade rules (p. 496)? How long was the real lag from about 1993?
2. Did invasions keep accumulating without saturation (p. 493)? What do later global syntheses say about rates, impacts and costs, and do they bear out the chapter’s cost claims (pp. 491, 494)?
3. Did the specific predictions hold? Ruddy duck eradicated in Europe by 2015 (p. 495)? Grey squirrel spreading across Europe (p. 495)? Grey squirrel trade stopped in Italy (p. 492)? Water hyacinth trade stopped (p. 492)? Biofuel crops producing new invasions (pp. 495, 501)? Aphalara itadori establishing and controlling knotweed (p. 496)?
4. Were voluntary codes of conduct evaluated after 2013, and did they perform better or worse than binding rules (pp. 493, 498–499)?
5. How did the scientific controversy evolve? Did the “novel ecosystems” and “don’t judge species on their origins” critique (pp. 494–495) gain or lose ground? Did the “philosophical debates” the chapter wanted not to block action (p. 502) in fact shape policy?
6. How good are white-list systems like New Zealand’s (p. 497) compared with black lists, and what trade-law friction have they met?
7. Who bears the costs? The chapter hints at the distribution (public budgets, allergy sufferers, native biodiversity, other jurisdictions) but never analyses it. Is there later work on distributional incidence?
8. Is the Caulerpa “missed opportunity” (p. 498) robust once we know what was understood in 1984? And what became of the Mediterranean invasion afterwards?
9. How should the tension between transparency about expert disagreement (p. 499) and “do not allow philosophical debates to create blockages” (p. 502) be resolved in a principled way, not by whoever holds the majority view?
10. Is “emerging technology” the right lens for a trade-driven hazard (p. 675)? Or does this chapter’s value lie in showing how governance fails for diffuse hazards with no single proponent?

Leads for the hindsight stage. These are from background knowledge and not verified in this pass. Check each against primary sources. - EU Regulation. Commission proposal COM(2013) 620 (September 2013). Regulation (EU) No 1143/2014, applying from 1 January 2015. First Union list adopted in 2016 (Implementing Regulation (EU) 2016/1141), since extended several times. Check whether water hyacinth, grey squirrel, ruddy duck, Ludwigia spp., signal crayfish and giant hogweed are listed, and whether Japanese knotweed and ragweed are not. Check the Commission’s review of the Regulation’s implementation. - Global trends and costs. Seebens et al. 2017, Nature Communications, “No saturation in the accumulation of alien species worldwide”. The IPBES 2023 Thematic Assessment on Invasive Alien Species (recalled figures: over 37,000 established alien species; annual costs over USD 400 billion in 2019; invasive species a major factor in about 60% of recorded extinctions). The InvaCost database (Diagne et al., 2021, Nature) and its European analyses, which offer a check on the Pimentel and Kettunen figures. Kunming–Montreal Global Biodiversity Framework (2022), Target 6. - Ruddy duck. Status of UK and European eradication after 2015: Bern Convention Standing Committee reports. - Grey squirrel in Italy. EU LIFE control projects after 2013; spread towards France and Switzerland. - Aphalara itadori. Field establishment and efficacy in the UK after release (CABI reports). - Caulerpa taxifolia. Reported regression of the Mediterranean invasion after about 2000; history of the 1984 detection and the 1989–1991 warnings. - Scientific debate. Russell and Blackburn 2017, Trends in Ecology & Evolution, on “invasive species denialism”, and replies. - Pathway standards. The IPPC standard on plants for planting (ISPM 36), adoption date.

Audit log#

Independent audit against the full text extract (report pp. 486–508), with Annex 1 biographies (pp. 687–697), the table of contents and cross-chapter passages (pp. 9, 609, 644, 651, 656, 674–676) re-checked in the PDF. Quotes, figures, dates and page references were checked line by line; the ten notable quotes are verbatim. Changes made:

1. Authors: replaced “run by Fernández-Galiano” with the Annex 1 wording (“in charge of” the Bern Convention since 1985).
2. Character of the chapter: Table 20.1 described as “mostly” a history of science and institutions (it does include Pliny’s harm and the CBD duty), not “not a record of warnings”.
3. Summary box: noted that its “high probability of unrestrained growth” is stronger than the body text’s “higher probability” (p. 495).
4. Summary box: “The science is contested” corrected to debate over management strategies, as the source says.
5. 20.1: “tens rule” relabelled as my gloss; the chapter neither names nor quantifies it.
6. 20.1: “a New Zealand study” for Harris and Timmins tagged as background (not in chapter).
7. 20.1: added omitted sentence on learning from lessons elsewhere (p. 487).
8. 20.4: added the chapter’s caveat that research approaches “have coexisted over time” (not successive eras); added Usher (1986) origin and the global-change point of the phase model.
9. 20.4: “Australian” weed risk assessment (Pheloung) tagged as background.
10. 20.5: added the IPPC’s scope limit, regional counterparts and national obligations, and governments’ listed roles (p. 491).
11. 20.6: corrected misattribution; context-dependence (cinnamon) is the chapter’s own “In addition” point citing Kueffer et al. 2010, not clearly part of the ISSG reply; noted it cuts both ways.
12. 20.6: noted that the US and China cost figures are uncited in the chapter and that the European figure varies (EUR 12.5bn p. 491 vs EUR 12bn p. 494).
13. 20.6: Davis et al. described from the reference list (title, 19 authors) rather than as “19 ecologists”.
14. 20.8: flagged “white list” as my label, not the chapter’s.
15. 20.9: “substitution logic” marked as my reading, asserted in the chapter for horticulture only; corrected AIPH name to the chapter’s wording.
16. 20.10: added the FAO biosecurity footnote (p. 501 fn 13), which also covers GMOs.
17. Table 20.1: “no harms” corrected (Pliny’s entry records one).
18. References: added five in-text citations missing from the list (Lambdon 2008, Hooker 1864, McLachlan 2007, Hunter 2007, Hoegh-Guldberg 2008) and two more uncited entries; self-citation count re-checked (about 36 of 122 entries).
19. Cross-chapter: noted that Ch. 25 p. 609 misnumbers all three chapters it cites (off by one), confirmed against the table of contents.
20. Timeline: Elton 1958 no longer labelled the “first clear” warning (19th-century concerns preceded it); c. 1993 date for “scientists alerted governments” flagged as inferred from Box 20.4’s arithmetic.
21. Mini-cases: Caulerpa “no record as an invader in 1984” tagged as background.
22. Lessons: lesson 2 now reports the hedged “may have hindered” rather than a recommendation to prefer simple actions; lesson 4’s “do not wait for precision” marked as implied.
23. Lessons (advocacy): added that the chapter body admits misidentification, biocontrol mis-assessment and caution over its best predictor.
24. Mechanisms: softened “no community of injured parties” (fisheries, farmers and allergy sufferers are harmed); “incompatible” definitions softened to hard-to-aggregate lists; “member states” narrowed to “some EU states … tend to”.
25. Interests: “public budgets” corrected to control and damage costs (the chapter does not say who pays); private-benefit/public-cost claim marked as my inference; industry substitution and “surfaces only” claims narrowed.
26. Framing: language point nuanced (the authors do avoid “black list”, fn 10).
27. Mental models: corrected misattribution of the “somewhere else” view, which the chapter gives to “biologists and conservationists”, not governments.
28. Transferable insights: #2 marked single-country evidence as background; #3 softened; #12 corrected, since the chapter says traits remain “highly relevant” (prediction from traits alone is insufficient, not a failure); added #21 on two-way misclassification (pp. 486, 488).
29. Bias check: EPPO role corrected (scientific officer, not leader); “only failures shown are other people’s” narrowed to institutional failures, noting the field-level self-criticism; critics’ coverage specified; “Two pages later” corrected to six, and the US figure no longer attributed to Pimentel; claim about when Europe’s aliens arrived tagged as background; Caulerpa cross-jurisdiction lesson tied to p. 487; ISSG “one of the oldest” no longer called an error.
30. Digest: author roles aligned with Annex 1 (Brunel scientific officer; Fernández-Galiano “in charge of” Bern Convention).
31. Digest: extinction figure given with its base (91 of about 170 with compiled causes; 34 sole cause); Europe’s impact shares added; “across the Mediterranean” corrected to “a large portion of”.
32. Digest: cost line now notes the EUR 12bn/12.5bn discrepancy, the Kettunen source (co-authored by Genovesi) and the chapter’s “according to this perspective” hedge.
33. Digest: “Prediction fails” softened to “Prediction is limited” (traits “highly relevant”); lag-phase liability claim softened to “may be lost”/”very difficult”; definitions line hedged; added two-way misclassification mechanism.
34. Digest: voluntary-codes line no longer generalises substitution to all industry; flags the industry claims as unsourced; grey squirrel account flagged as one-sided.
35. Digest: lessons 1, 3, 4 given fuller headings and the implied status of “paralysis by analysis” noted.
36. Digest: added three transferable insights (limits of intrinsic-property prediction; stakeholder vs expert criteria; misclassification); hedged two existing ones.
37. Digest caveats: “no counter-voice” corrected (critics summarised briefly, no panel); US/China figures noted as uncited; added field-vs-institution self-criticism caveat; false-positive caveat tied to p. 9; biofuel item reframed as a stated risk rather than forecast.