Alan MacLeod

Bio: Alan MacLeod is an academic researcher from Food and Environment Research Agency. The author has contributed to research in topics: European union & PEST analysis. The author has an hindex of 26, co-authored 252 publications receiving 2785 citations. Previous affiliations of Alan MacLeod include Central Science Laboratory & University of Southampton.

Guidance on quantitative pest risk assessment

Abstract: This Guidance describes a two-phase approach for a fit-for-purpose method for the assessment of plant pest risk in the territory of the EU. Phase one consists of pest categorisation to determine whether the pest has the characteristics of a quarantine pest or those of a regulated non-quarantine pest for the area of the EU. Phase two consists of pest risk assessment, which may be requested by the risk managers following the pest categorisation results. This Guidance provides a template for pest categorisation and describes in detail the use of modelling and expert knowledge elicitation to conduct a pest risk assessment. The Guidance provides support and a framework for assessors to provide quantitative estimates, together with associated uncertainties, regarding the entry, establishment, spread and impact of plant pests in the EU. The Guidance allows the effectiveness of risk reducing options (RROs) to be quantitatively assessed as an integral part of the assessment framework. A list of RROs is provided. A two-tiered approach is proposed for the use of expert knowledge elicitation and modelling. Depending on data and resources available and the needs of risk managers, pest entry, establishment, spread and impact steps may be assessed directly, using weight of evidence and quantitative expert judgement (first tier), or they may be elaborated in substeps using quantitative models (second tier). An example of an application of the first tier approach is provided. Guidance is provided on how to derive models of appropriate complexity to conduct a second tier assessment. Each assessment is operationalised using Monte Carlo simulations that can compare scenarios for relevant factors, e.g. with or without RROs. This document provides guidance on how to compare scenarios to draw conclusions on the magnitude of pest risks and the effectiveness of RROs and on how to communicate assessment results.

'Beetle banks' as refuges for beneficial arthropods in farmland: long-term changes in predator communities and habitat

Abstract: Significant differences in the overwintering densities of predatory carabid and staphylinid beetles and spiders occurred on an 'island' grassy bank habitat composed of blocks of Agrostis stolonifera, Dactylis glomerata, Holcus lanatus and Lolium perenne, within and between winters during a 7-year study. 2 Densities of the predators over the last three winters of the study were greater in the bank than in the boundary of the field in which the bank was situated. 3 Succession occurred in plots of L. perenne, with D. glomerata fully replacing this species. Plots of D. glomerata and H. lanatus remained virtually mono- specific. 4 Over the period of study, the beetle bank maintained its role in providing overwintering habitat for polyphagous predators and carabid diversity has increased since the bank was first established. Beetle banks were therefore shown to contribute to conservation biodiversity in an agroecosystem.

Evolution of the international regulation of plant pests and challenges for future plant health

Abstract: Plant pathogens and invertebrates harmful to plants, collectively referred to as plant pests, continue to threaten food security. International cooperation and regulatory systems to inhibit the spread of plant pests began formally in 1878. Initially seven countries worked together and agreed phytosanitary measures against grape phylloxera, Phylloxera vastatrix (=Daktulosphaira vitifoliae). There are now 172 countries that are contracting parties to the International Plant Protection Convention, a treaty that aims to prevent the introduction and spread of pests of plants and plant products, and to promote appropriate measures for their control. Apparently contradictory interests between international trade, which has facilitated the spread of plant pests, and the protection of plants are mutually recognised in global trade and phytosanitary agreements. The principle that risk management measures should provide an appropriate level of protection without undue interference in trade was established within the plant protection agreements at the beginning of the 20th Century and is still fundamental to risk management policy today. Globally ten Regional Plant Protection Organizations facilitate more local cooperation and recommend the regulation of over 1,000 named quarantine plant pests. Member States of the European Union work together and regulate imported plant material on the grounds of plant health with each Member State taking into account the plant health concerns of every other Member State. However, decision making can be slow and border inspections poorly targeted. Close relationships between regulatory scientists and policy makers, focussed on agricultural and horticultural production, are changing to take a broader stakeholder community into consideration as decisions regarding the environment seek to draw upon a wider knowledge base. Challenges that impede the success of limiting international pest movement include increased international trade and climate change. International guidelines designed to prevent pest spread present challenges of their own if they remain difficult to implement.

Extinction risk from climate change

Abstract: Climate change over the past approximately 30 years has produced numerous shifts in the distributions and abundances of species and has been implicated in one species-level extinction. Using projections of species' distributions for future climate scenarios, we assess extinction risks for sample regions that cover some 20% of the Earth's terrestrial surface. Exploring three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size, we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15-37% of species in our sample of regions and taxa will be 'committed to extinction'. When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction ( approximately 18%) than mid-range ( approximately 24%) and maximum-change ( approximately 35%) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration.

How well do we understand the impacts of alien species on ecosystem services? A pan-European, cross-taxa assessment

Abstract: Recent comprehensive data provided through the DAISIE project (www.europe-aliens.org) have facilitated the development of the first pan-European assessment of the impacts of alien plants, vertebrates, and invertebrates – in terrestrial, freshwater, and marine environments – on ecosystem services. There are 1094 species with documented ecological impacts and 1347 with economic impacts. The two taxonomic groups with the most species causing impacts are terrestrial invertebrates and terrestrial plants. The North Sea is the maritime region that suffers the most impacts. Across taxa and regions, ecological and economic impacts are highly correlated. Terrestrial invertebrates create greater economic impacts than ecological impacts, while the reverse is true for terrestrial plants. Alien species from all taxonomic groups affect “supporting”, “provisioning”, “regulating”, and “cultural” services and interfere with human well-being. Terrestrial vertebrates are responsible for the greatest range of impacts, and these are widely distributed across Europe. Here, we present a review of the financial costs, as the first step toward calculating an estimate of the economic consequences of alien species in Europe.

Methods and uncertainties in bioclimatic envelope modelling under climate change

Abstract: Potential impacts of projected climate change on biodiversity are often assessed using single-species bioclimatic 'envelope' models. Such models are a special case of species distribution models in which the current geographical distribution of species is related to climatic variables so to enable projections of distributions under future climate change scenarios. This work reviews a number of critical methodological issues that may lead to uncertainty in predictions from bioclimatic modelling. Particular attention is paid to recent developments of bioclimatic modelling that address some of these issues as well as to the topics where more progress needs to be made. Developing and applying bioclimatic models in a informative way requires good understanding of a wide range of methodologies, including the choice of modelling technique, model validation, collinearity, autocorrelation, biased sampling of explanatory variables, scaling and impacts of non- climatic factors. A key challenge for future research is integrating factors such as land cover, direct CO2 effects, biotic interactions and dispersal mechanisms into species-climate models. We conclude that, although bioclimatic envelope models have a number of important advantages, they need to be applied only when users of models have a thorough understanding of their limitations and uncertainties.