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Guidance on the environmental risk assessment of plant pests
The European Food Safety Authority (EFSA) requested the Panel on Plant Health to develop a methodology for assessing the environmental risks posed by harmful organisms that may enter, establish and spread in the European Union. To do so, the Panel first reviewed the methods for assessing the environmental risks of plant pests that have previously been used in pest risk assessment. The limitations identified by the review led the Panel to define the new methodology for environmental risk assessment which is described in this guidance document. The guidance is primarily addressed to the EFSA PLH Panel and has been conceived as an enhancement of the relevant parts of the “Guidance on a harmonised framework for pest risk assessment and the identification and evaluation of pest risk management options by EFSA”. Emphasizing the importance of assessing the consequences on both the structural (biodiversity) and the functional (ecosystem services) aspects of the environment, this new approach includes methods for assessing both aspects for the first time in a pest risk assessment scheme. A list of questions has been developed for the assessor to evaluate the consequences for structural biodiversity and for ecosystem services in the current area of invasion and in the risk assessment area. To ensure the consistency and transparency of the assessment, a rating system has also been developed based on a probabilistic approach with an evaluation of the degree of uncertainty. Finally, an overview of the available risk reduction options for pests in natural environments is presented, minimum data requirements are described, and a glossary to support the common understanding of the principles of this opinion is provided.
© European Food Safety Authority, 2011
The European Food Safety Authority (EFSA) asked the Panel on Plant Health to develop a guidance document on the environmental risk assessment of plant pests. The purpose of this document is to develop a methodology for assessing the environmental risks posed by non-endemic living organisms harmful to plants and/or plant products that are associated with the movement of plants and plant products, and that may enter into, establish and spread in the European Union. The range of the organisms of concern includes phytophagous invertebrates, plant pathogens, parasitic plants and invasive alien plant species.
The document is primarily addressed to the EFSA PLH Panel and has been conceived as an extension of the relevant parts of the “Guidance on a harmonised framework for pest risk assessments and the identification and evaluation of pest risk management options by EFSA” (EFSA Panel on Plant Health (PLH), 2010). It also forms part of an EFSA initiative across all areas of its remit covering guidance for environmental risk assessment.
In this document, the available methodologies for assessing environmental risks of plant pests within the framework of pest risk assessment are reviewed, a new procedure for environmental risk assessment is defined, and its scientific principles are outlined. Therefore, the main scope of this document is the delivery of a sound tool for the evaluation of the environmental risks, including the identification of risk reduction options that may reduce the impact of a pest on the environment. The document is to be applied by the EFSA PLH Panel and will extend the “Guidance on a harmonised framework for pest risk assessments and the identification and evaluation of pest risk management options by EFSA” (EFSA Panel on Plant Health (PLH), 2010).
By the development of this environmental risk assessment guidance document the PLH Panel aims at harmonising its outputs and implementing a common and explicit methodology for the evaluation of the environmental risks in PLH outputs when relevant, and to contribute to the overall EFSA effort in environmental risk assessment.
Based on its work, the Panel came to the conclusions presented below:
Although every pest risk assessment scheme based on ISPM No 11 includes an assessment of the environmental consequences of pest introduction, schemes focus primarily on the effects on biodiversity, without defining this clearly, and do not provide an explicit standardised methodology for assessing the consequences on ecosystem services. Therefore, the EFSA PLH Panel has developed a scheme that provides guiding principles on assessment practices and enhanced approaches for assessing the environmental risks caused by plant pests. The scheme takes into account the consequences for both biodiversity and ecosystem services.
Review of current approaches
The Panel first reviewed the current approaches and methodologies that assess environmental risks related to pests. In its previous scientific opinions, the Panel assessed environmental risks on an ad hoc basis, without following a clear approach and consistent methodology. In most cases, environmental consequences have been interpreted in terms of biodiversity loss. The existing pest risk analysis schemes (e.g. from EPPO, Canadian Food Inspection Agency, USDA and Biosecurity Australia) that are based on the text of ISPM No 11, mostly provide only general guidance to the assessor to help the assessor decide what elements of the “environment” need to be considered and what risk rating is appropriate. These also primarily assess risk according to biodiversity loss (direct effects according to ISPM No 11) and there is little guidance on assessing the consequences on ecosystem processes and services (included in the list of indirect effects according to ISPM No 11). Although risk ratings still have to be justified by written text, the lack of specific guidance can lead to considerable inconsistencies. However, where applied, the principle of assessing consequences in the current area of invasion and extrapolating to the risk assessment area was considered to be a useful approach. The activities of the PRATIQUE and Prima phacie projects have focussed on the enhancement of the structural biodiversity component of environmental risk, and their approach has been reviewed and considered during the development of the current document, although we have provided a more comprehensive evaluation and adopted a different risk rating system. A serious shortcoming of all the considered schemes is the lack of an explicit evaluation of the consequences on ecosystem services and this provides a major focus of this document.
Methodology to prepare an environmental risk assessment
Next, the Panel developed a new methodology for environmental risk assessment. There are two basic reasons to be concerned about environmental consequences. The first one is the international obligation to protect biodiversity, particularly because biodiversity is essential for the normal functioning of ecosystems. The second one is that the outcomes of several ecological processes – the ecosystem services – are useful and indispensable for humans, and their continued functioning is important. This approach emphasizes the importance of assessing consequences on both the structural (biodiversity) and the functional (ecosystem services) levels of the environment. The document presents an approach which considers for the first time the inclusion of both biodiversity and ecosystem services perspectives in a pest risk assessment scheme is presented.
Biodiversity. The assessment of the potential effects of a pest on biodiversity starts with concerns emerging from legal/administrative constraints (e.g. protected/red-list species), and gradually moves towards a more ecological perspective, preparing the ground for the second stage of evaluation, the assessment of the consequences on ecosystem services. The biodiversity at the different organisational levels, from infra-individual to landscape/ecosystem levels is considered, and the potential consequences on genetic, species and landscape diversity are assessed and scored separately. There is a consistent distinction between elements of structural biodiversity that are legally protected, and elements of native biodiversity, and the consequences for these are scored separately.
Ecosystem services. For an environmental risk assessment of pests based on ecosystem services, it is necessary: (1) to identify the environmental components or units responsible for the genesis and regulation of the ecosystem services, the so-called “service providing units”; they are regarded as functional units in which the components (individuals, species or communities) are characterized by functional traits defining their ecological role; (2) to assess the impact of the pest on the components of the structural biodiversity at the genetic, species, habitat, community, and ecosystem levels; (3) to establish a procedure for the evaluation of the effects of pests on ecosystem services. The objective of an environmental risk assessment based on ecosystem services is to understand the consequences of invasion in terms of the modification of the functional traits that are components of the service providing units. Changes in functional traits are associated with the variation in ecosystem services provision levels by means of the consideration of trait-service clusters. The modification of functional traits by the action of pests influences ecosystem processes at the individual (e.g. survival), population (e.g. population structure), as well as community level (importance of functional groups). From the analysis of the traits, a table is derived listing: i) the target elements of the service providing units affected by the pest, ii) the functional traits affected by the pest, iii) whether the induced modification is positive or negative and iv) if necessary, relevant comments clarifying the interpretation of the analysis performed. This guidance document proposes the use of explorative scenarios related to the environmental risk associated with pests. Explorative scenarios are attempts to explore what future developments may be triggered by a driving force, in this case an exogenous driving force, i.e. a driving force that cannot or can only partially be influenced by decision makers.
For the list of the ecosystem services to be considered in environmental risk assessment, the Panel adopted the list originally proposed by the Millennium Ecosystem Assessment (MA, 2005). Concerning provisioning services, the complete list has been considered in this document. This choice raises the issue of a possible double accounting, since some of the items in the list have already been, at least partially, considered in the impact session of the pest risk assessment. However, the consideration of all the provisioning services allows for a comprehensive impact evaluation that is not limited to market value, but considers also other components of the value of the ecosystem services. The consideration of the impact on the provisioning services is therefore useful for a more comprehensive environmental impact assessment even for those components of ecosystems more directly computable in terms of market value (e.g., crops).
Questions for assessors. The environmental risk assessment questions for the assessors address the following topics:
- The definition of the background and assumptions to the ecosystem services approach (e.g. identification of the service providing units and elements of biodiversity ecologically linked to the service providing units) as well as the temporal and spatial scale, to estimate the resistance and the resilience of the affected service providing units, to identify the trait-service clusters and to list the risk reduction options.
- The evaluation of the consequences for structural biodiversity caused by the pest in the current area of invasion: what is the magnitude of change on genetic diversity, are protected, rare or vulnerable species affected, is there a decline in native species, is there an impact on objects or habitats of high conservation value, are there changes in the composition and structure of native habitats, communities and/or ecosystems?
- The evaluation of the consequences for structural biodiversity caused by the pest in the risk assessment area: similar questions as under point 2.
- The evaluation of the consequences for ecosystem services caused by the pest within its current area of invasion, to determine how great the magnitude of reduction is in the provisioning, regulating and supporting services affected in the current area of invasion.
- The evaluation of the consequences for ecosystem services caused by the pest within the risk assessment area: similar questions as under point 4.
Rating system. A rating system has been developed based on a probabilistic approach which ensures consistency and transparency of the assessment. The rating system includes an evaluation of the degree of uncertainty. The rating system makes it possible to evaluate the level of risk and the associated uncertainty for every sub-question and then the overall risk and uncertainty for every question. At the end of the assessment process, the level of overall risk related to questions on biodiversity is categorized as either Minor, Moderate or Major, while for questions on ecosystem services, the categorisation is either Minimal, Minor, Moderate, Major or Massive. The degree of uncertainty is categorised as Low, Medium or High.
Finally, an overview of the available risk reduction options for pests in natural environments is presented, minimum data requirements are described, and a glossary to support the common understanding of the principles of this opinion is provided.
The Panel recognises that assessing environmental impacts on the basis of the ecosystem services concept is a developing area, and expects methodological developments and more precise and articulate schemes and quantification methods to emerge as experience accumulates. Attention has to be devoted to the evaluation of the provisioning services in order to avoid the possible problem of double accounting, and before evaluating them in the environmental risk assessment, it should be assessed whether these are not already satisfactorily covered in other parts of the pest risk assessment.
The Panel recommends revising and updating the present guidance document in three years, based upon:
- outcome and experience gained from the usage of the proposed environmental risk assessment approach in future pest risk assessments;
- results of horizontal harmonisation activities within EFSA;
- any relevant new information which may have an impact on the current opinion, e.g. further developments in the ecosystem services concept and its application.
Further work is recommended by the Panel, e.g.
- testing the scheme using species with a wide range of environmental impacts;
- comparing this approach with that used in other schemes from the perspective of the risk assessor, risk manager and risk modeller;
- exploring the possibility to use quantitative assessment (percentages) to describe levels of impact in other parts of the pest risk assessment;
- exploring the potentiality of the scenario exercise (leading to a set of assumptions guiding the assessment procedure) for the entire pest risk assessment.
Biodiversity, ecosystem functioning, ecosystem services, environmental impact, environmental risk assessment, global change