Environmental Governance of Invasive Species

An EU Perspective

Donato Gualtieri

• Publisher: Taylor & Francis
• Year: 2017
• eBook ISBN: 9781351867658
• Edition: 1
• Topic: Law
• Subtopic: Environmental Law
• Index: Law

The consequences of the introduction and spread of invasive alien species in non-native ecosystems is an area of growing interest for international policymakers and regulators. Globalisation has increased the rate and magnitude of biological invasions, resulting in huge environmental, economic and social costs. Until recently, the effectiveness of international efforts to provide a coordinated response to the threat of alien invasions have been limited. This book considers the existing Multilateral Environmental Agreements and looks at the potential role of regional environmental governance, particularly in consideration of the adoption of the European Parliament and Council regulation 1143/2014 on the management and control of invasive species, to provide an effective response to this global threat.

1 Background information on biological invasions

SUMMARY: 1.1. Introduction – 1.2. Preliminary clarifications: definitions and key terms – 1.3. Analysing biological invasions under the lenses of the DPSIR model (a. At the roots of biological invasions: pressures exerted by driving forces; b. Impacts of invasive alien species on the state of natural and human environment; c. The role of policy-makers in response to biological invasions) – 1.4. Is there a role for supranational environmental regulation?

1.1 Introduction

Centuries-old olive trees dried up with rotting leaves, trunks flaked off, in a region which has shaped its landscape, history, cultural identity and economic welfare around a symbiotic relationship with those plants. Olea europaea covers 60% of the entire territory of the Salento peninsula in the southern region of Apulia (Italy), and ensures an average annual production of 3,000,000 quintals of olives (30% of the national total) and 500,000 quintals of olive oil (80% of the national total).

According to studies by the European Commission and the European Food Safety Authority (European Commission, 2015; EFSA, 2015a; EFSA, 2015b), the bacterium Xylella fastidiosa, in its subspieces pauca, has, since 2013, infected around 10% of the 11 million autochthonous olive trees with the so-called Olive Quick Decline Syndrome (OQDS)¹ In the short span of three years 1,600 plants have already been eradicated in order to contain the impact of the disease to a limited area, and there exists a climate of escalating tension between the European Commission, national authorities and local environmental NGOs and farmers associations.²

The pathogen proliferates in the lymph-conducting vessels of leaves and causes the obstruction of xylematic veins, ultimately blocking the plant’s nutrition and leading to a series of alterations. Younger plants (around 50–60 years of age) suffer from withering and desiccation of scattered shoots and small branches; in centenarian trees consequences are far more serious, as the symptoms extend to the rest of the canopy and ultimately lead to structural collapses (Cariddi et al., 2014).

Native to Costa Rica (where a ST53 twin-strain has caused diseases in oleanders, mango and macadamia nuts), this particular strain of Xylella fastidiosahas been introduced to Europe through trade in ornamental plants: the most likely hypothesis postulates that the bacterium has entered Europe via the port of Rotterdam, the main continental access point for different varieties of plants native to Central and South America. It is possible that the pathogen infiltrated some coffee plants, healthy carriers of the bacterium where its presence is totally asymptomatic, and then reached Salento as a “hitchhiker” of the Meadow froghopper (Philaenus spumarius), an insect already identified as a vector of many Xylella-related diseases, such as Pierce’s disease in many Californian vineyards (Purcell, 1980).³ Once introduced, Xylella fastidiosa found a particularly suitable environment for its reproduction and establishment, as emphasised by the report issued by the EFSA in January 2015 (EFSA, 2015a). Climatic and biological factors have particularly facilitated the uncontrolled spread of the bacterium: from the first standpoint, it is very likely that the pathogen thrived in a region where the summer climate is torrid while winters are generally mild and humid (Hoodle, 2004) As for the biologic factor, no competing species (i.e. other microbes) are as yet known to displace Xylella fastidiosa, while its natural enemies (i.e. specific bacteriophages) are geographically contained to North America (Summer et al., 2010; Ahern et al., 2014), or can only attack the vector with limited effects in terms of control (Waloff, 1980; Ceresa-Gastaldo and Chiappini, 1994; Eilenberg et al., 2001). Still, the EFSA report gives a solid rationale for considering this case of biological invasions as a priority matter for the European Union (EU), with particular reference to its environmental and socio-economic impact:

the overall potential consequences … in the European continent are rated as major considering the severe losses on olive in the Apulian outbreak… . In commercial crops, when conditions are suitable for symptom expression and efficient vectors are present, yield losses and damage would be high and imply costly control measures. The disease also has a negative social impact since it is not readily controllable in smallholdings and family gardens… . In addition to those elements, the use of insecticide may have environmental impacts.

(EFSA, 2015a)

Given these considerations, this extreme southeastern offshoot of Italy is currently both a privileged viewpoint and one of the most recent cases of biological invasion, a phenomenon generally characterised by “a species’ acquiring a competitive advantage following the disappearance of natural obstacles to its proliferation, which allows it to spread rapidly and to conquer novel areas within recipient ecosystems in which it becomes a dominant population” (Valery et al., 2008).

This chapter primarily aims at providing an exhaustive yet synthetic overview of the main aspects of biological invasions. In this sense, a first necessary step is the exact determination of what invasive alien species are: an enquiry on the biological and legal meaning of relevant terms helps to piece together a univocal and coherent bio-legal definition. Subsequently, the use of the DPSIR (Driving forces-Pressure-State-Impact-Response) model – a causal framework elaborated by the European Environmental Agency (EEA) in the 1990s – shows how biological invasions find their primary cause in the progressively expanding role of human agency, conceived as a multi-level combination of driving forces which exerts pressures on nature. A closer look at policy responses to biological invasions emphasises the role of a three-tier approach focused on prevention, control and eradication of invasive species and the need for a multilateral response capable of transcending national borders in order to achieve a multi-level regulation, the effectiveness of which will be analysed in greater detail in the next chapter.

1.2 Preliminary clarifications: definitions and key terms

Broadening the picture with respect to the case of Xylella fastidiosa, the occurrence of a biological invasion is far from exceptional. The phenomenon regards – to a greater or lesser extent – all taxonomic groups and biological realms in almost every region of the world. Virtually no ecosystem can be considered safe from the vast array of threats invasive alien species pose, not only to the environment but also to human health and socio-economic wellbeing. Such threats often exceed national borders and capacities. It is thus not difficult to understand why a domain once reserved for natural scientists has gradually become a central issue in national and international law and policy-making.

Before analysing the legal and political framework in greater detail it seems useful to provide some background information on biological invasions, beginning with the identification of key terms and the formulation of a comprehensive definition of the expression “invasive alien species”. Indeed, many definitions have been stratified over the decades thanks to the relentless interest of conservationists and biologists on the matter. Nevertheless, this semantic abundance has been at the source of many ambiguities and misconceptions at a time when such a delicate and multi-faceted issue has become an object of regulatory intervention. Ambiguities are also related to the different outcomes of natural and legal research: the first, in fact, is more oriented to investigate the causes of a phenomenon; the latter, in turn, is particularly focused on the effects and possible remedies of a fact. In this sense, it would be useful to streamline and condense in standard, coherent, comprehensive bio-legal definitions the complex ecological processes which lie underneath biological invasions.

A preliminary clarification as regards the definition of what a “species” is can be found in the Guidelines for the Prevention of Biodiversity Loss caused by Invasive Alien Species, developed in 2000 by the International Union for the Conservation of Nature (IUCN). The Guidelines offer a comprehensive explanation which satisfies both scientific precision and legal certainty, as they are defined as “subspecies and lower taxa, as well as any part, gametes, seeds, eggs or propagule of such species that might survive and subsequently reproduce” (SSC-ISSG, 2000). In fact, the process of biological invasion – and its related damages – can be caused not only by species, but also by lower taxonomic units. Once identified as the object of the research, it is of paramount importance to understand the meaning of the adjectives “alien” and “invasive”. Even though the commonly accepted expression is “invasive alien species”, a species becomes “alien” at first and “invasive” later.

The term “alien” has been officially introduced at the international level through Article 8(h) of the Convention on Biological Diversity (CBD), obliging each Contracting Party to prevent “as far as possible and as appropriate … the introduction of, control or eradicate those alien species which threaten ecosystems, habitats or species”. Furthermore, the Guiding Principles for the Prevention, Introduction and Mitigation of Impacts of Invasive Alien Species, developed by the Subsidiary Body on Scientific, Technical and Technological Advice in the framework of the Convention on Biological Diversity in 2000, use the word “alien” as encompassing a series of expressions (such as “non-native”, “exotic”, “foreign”, “new”) employed to identify species found outside their “normal distribution”. In 2002, in turn, Decision VI/23 of the Conference of Parties to the CBD changed the definition to “species occurring outside its natural past or present distribution”. This concept is both temporal and spatial, as it includes the past and present range of distribution of a species, on the one hand, and its dispersal potential, on the other. However, such an apparently precise definition risks being “poorly-suited” to regulatory purposes for two main reasons (Shine et al., 2000). On the one hand, the concept of “natural distribution” better corresponds to ecological than political boundaries. This constitutes a source of difficult employability of the concept in legal reasoning, as law-making follows jurisdictional – i.e. artificial – boundaries rather than natural ones. On the other hand, there are many cases in which it is not possible to determine if species are native to a certain area, have arrived there through their own natural dispersal abilities, or have been pushed beyond those limits in the near or remote past thanks to human assistance. A possible solution to such an insidious dilemma is to focus the analysis on the role played by human agency in the relevant process of introduction of a given species in a particular ecosystem. For many centuries, in fact, the spread of non-native organisms inside a host region has been a totally natural phenomenon, whose dimensions were limited by entirely ecological factors. Many species had, in fact, very reduced dispersal abilities and could not travel for long distances; at the same time, rivers, mountains and oceans provided insurmountable barriers to the diffusion of living organisms beyond their usual ranges. Similarly, the pathways of introduction were entirely natural: ocean currents, winds, earth movements and continental shifts (Shine, 2008). In brief, introductions respected millennial mechanisms called to protect the environmental balance, and changes occurred at an utterly gradual speed (Shine, 2008). The phenomenon of biological invasions became global with the so-called “Age of Discoveries”, which lasted from the early 15th century to the end of the 17th century. The dislocation of alien species over long distances and beyond natural borders was, indeed, a logical complement of transoceanic trade and of the settlement of overseas colonies by many of the European powers. After the discovery of the American continent, the process of species dispersal accelerated, acquiring uncontrolled and sometimes dangerous characteristics: the so-called Columbian Exchange – defined by the environmental historian Alfred W. Crosby as a phenomenon of ecological imperialism (Crosby, 1986) – allowed many Eurasian species to invade the New World, often with devastating impacts. With the differentiation of global routes of exchange in recent decades, a quantitatively higher and geographically wider volume of human beings and manufactured goods started to spread, while at the same time the increase in the efficacy and use of rapid means of transport made distances shorter and borders more porous. New pathways of introduction have been set up, and the flow of the introductions ceased to be unidirectional. As an example, one of the most active global pathways currently is the “Pacific hallway” between Asia and North America.

Human agency thus plays a primary role in defining the magna divisio between “native” and “alien” species, provided that the adjective “native” is intended here in biological terms to indicate a species evolved in a particular habitat, or grown elsewhere but autonomously arrived in a region. At the same time, however, the intervention of humans is not a sufficient condition to turn an “alien” into an “invasive” species, intended as a population of introduced individuals which succeed in colonising their host environment by establishing a significant population capable of resisting the initial threat of extinction and, subsequently, to maintain itself without further human intervention through a process of assimilation, or naturalisation, to their new bioregion. However, this course of events is extremely unlikely: the overall rate of successful introductions – meaning the total percentage of introduced species which succeed in becoming established – is actually quite low, as much as the possibility that established species may become capable of spreading and becoming invasive (Keller et al., 2011).

In the late 1980s, Di Castri estimated that only 10% of alien species could survive introductions in new habitats, and that the likelihood of a surviving species successfully out-competing native populations and thriving in the new location could be estimated at around 20–30%. In absolute terms, then, the actual possibilities of a successful biological invasion were considered to be less than 3% (Di Castri, 1989). In 1996, Williamson and Fitter proposed the “tens rule”, holding that only 10% of alien species survive introductions to new habitats, with a 10% likelihood that a surviving species could succeed in out-competing native populations and thrive in the new location (Williamson and Fitter, 1996). Since then, scholarship has gradually agreed on two main facts: on the one hand, such a figure was absolutely underestimated; on the other, it is very difficult to have a single percentage on invasions, since each species has a peculiar degree of invasiveness. Later studies on vertebrate invasions in Europe and North America conducted in 2005 by Jeschke and Strayer suggested that the overall rate of successful introduction and spread might be comprised in a wide confidence interval from 5% to 75% for each of the steps of the process (Jeschke and Strayer, 2005). Overall, and from a rigorous biological standpoint, only a fraction of “alien” species is entitled to be called “invasive” as a result of the combination of four factors: a high reproduction rate, which allows invasive species to rapidly colonise their new habitat; the ability to tolerate a wide range of environmental conditions; a generalist attitude towards alimentation, in a way to take advantage of a variety of resources; the lack of natural predators in the new environment; and/or the presence of an ecological niche that the species is able to fill.

Once a species is classified as “invasive”, it is also important to determine the stage of the invasion: according to Colautti and McIsaac this classification is deeply influenced by the distribution and abundance of the non-native species, considered as individual populations and not at a more aggregate level. In this sense, there are five stages in an invasion process, from stage 0, where propagules are still present in the native area of a potential invader, to stage 5, when invasive species are widespread and dominant in a host environment. Each stage is reached as soon as the non-native species has overcome a barrier to its introduction and diffusion (Colautti and McIsaac, 2004). A more detailed categorisation defines three subsequent phases in the invasion process: a “lag phase”, which starts with the arrival of a numerically irrelevant number of non-native species in a new habitat and ends with the elimination or naturalisation of the species; the “expansion phase”, characterised by an increase in the abundance and geographical distribution of the species in the host environment; and a “persistence phase”, in which the invasive species succeeds in o...

Table of contents

• Cover
• Title
• Copyright
• Dedication
• Contents
• Acknowledgements
• List of tables
• List of acronyms and abbreviations
• Introduction
• 1 Background information on biological invasions
• 2 Gaps in the global legal framework and the regional alternative
• 3 The European Union and its role in addressing the threat of biological invasions: regional environmental governance at work
• 4 EU regulation 1143/2014: genesis, adoption and implementation: an assessment
• Conclusions
• Regulation (EU) No 1143/2014 of the European Parliament and of the Council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species
• Index