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Policy makers increasingly acknowledge the importance of considering ecosystem services (ESs) and biodiversity in impact assessment (IA) to reduce ecosystem degradation and halt ongoing losses of biodiversity. Recent research demonstrates how ESs can add value to IA, i.e., by shifting the focus from avoiding negative impacts to creating opportunities, by linking effects on ecological functioning to benefits for society, and by providing a multi-disciplinary framework that allows to consider cross-sectoral effects. However, challenges exist to its implementation in practice. The most commonly used ES models do not consider interactions among ESs. This restricts their capacity to account for cross-sectoral effects. Integrating ESs into IA also increases time investments as they cover a wide variety of disciplines and need detailed information. This paper presents a pragmatic approach that tackles these challenges and may facilitate the inclusion of ESs into IA. The approach focuses on ecosystem processes as the driver of ESs and biodiversity and the basis to evaluate effects of a project. Using the Belgian coastal ecosystem, we illustrate how the approach restricts data needs by identifying the priority ESs, how it improves the coverage of cross-sectoral effects in IA, and how it contributes to a more objective selection of impacts. [ABSTRACT FROM AUTHOR]

Non-native Berberis aquifolium is an invasive species in Belgian coastal dunes. With its strong clonal growth through suckers, this evergreen shrub outcompetes native species and affects dune succession. To prevent further secondary spread and mitigate its impact, there was an urgent need for knowledge on the effectiveness of control measures, both at the plant and habitat level. Here, we report on a first control experiment. Individual B. aquifolium clones were subjected to one of four treatments (manual uprooting, foliar herbicide application, stem cutting followed by herbicide or salt application), with regrowth being measured up to one year after treatment. We analyzed the relationship between kill rate, treatment, dune area, plant volume and number of plant stems using a generalized linear model. Berberis aquifolium plants proved most susceptible to foliar herbicide application (5% glyphosate solution), resulting in 88% (64%– 97%) of the clones dying after treatment. The predicted kill rate decreased with an increasing number of stems under all treatments. We discuss the limitations of our experiment and the potential for actual field application of the different treatments. We present some guidelines for future control that may become further refined as experience builds up and we provide some recommendations for tackling invasive alien species in Atlantic dune ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Biological invasions are a threat to biodiversity, society and the economy. There is an urgent need to provide evidence‐based assessments of the risks posed by invasive alien species (IAS) to prioritize action. Risk assessments underpin IAS policies in many ways: informing legislation; providing justification of restrictions in trade or consumer activities; prioritizing surveillance and rapid response. There are benefits to ensuring consistency in content of IAS risk assessments globally, and this can be achieved by providing a framework of minimum standards as a checklist for quality assurance. From a review of existing risk assessment protocols, and with reference to the requirements of the EU Regulation on IAS (1143/2014) and international agreements including the World Trade Organisation, Convention on Biological Diversity and International Plant Protection Convention, coupled with consensus methods, we identified and agreed upon 14 minimum standards (attributes) a risk‐assessment scheme should include. The agreed minimum standards were as follows: (1) basic species description; (2) likelihood of invasion; (3) distribution, spread and impacts; (4) assessment of introduction pathways; (5) assessment of impacts on biodiversity and ecosystems; (6) Assessment of impact on ecosystem services; (7) assessment of socio‐economic impacts; (8) consideration of status (threatened or protected) of species or habitat under threat; (9) assessment of effects of future climate change; (10) completion possible even when there is a lack of information; (11) documents information sources; (12) provides a summary in a consistent and interpretable form; (13) includes uncertainty; (14) includes quality assurance. In deriving these minimum standards, gaps in knowledge required for completing risk assessments and the scope of existing risk assessment protocols were revealed, most notably in relation to assessing benefits, socio‐economic impacts and impacts on ecosystem services but also inclusion of consideration of climate change. Policy implications. We provide a checklist of components that should be within invasive alien species risk assessments and recommendations to develop risk assessments to meet these proposed minimum standards. Although inspired by implementation of the European Union Regulation on invasive alien species, and as such developed specifically within a European context, the derived framework and minimum standards could be applied globally. [ABSTRACT FROM AUTHOR]

Abstract: Effective prevention and control of invasive species generally relies on a comprehensive, coherent and representative list of species that enables resources to be used optimally. European Union (EU) Regulation 1143/2014 on invasive alien species (IAS) aims to control or eradicate priority species, and to manage pathways to prevent the introduction and establishment of new IAS; it applies to species considered of Union concern and subject to formal risk assessment. So far, 49 species have been listed but the criteria for selecting species for risk assessment have not been disclosed and were probably unsystematic. We developed a simple method to systematically rank IAS according to their maximum potential threat to biodiversity in the EU. We identified 1,323 species as potential candidates for listing, and evaluated them against their invasion stages and reported impacts, using information from databases and scientific literature. 900 species fitted the criteria for listing according to IAS Regulation. We prioritised 207 species for urgent risk assessment, 59 by 2018 and 148 by 2020, based on their potential to permanently damage native species or ecosystems; another 336 species were identified for a second phase (by 2025), to prevent or reverse their profound impacts on biodiversity; and a further 357 species for assessment by 2030. Policy implications. We propose a systematic, proactive approach to selecting and prioritising IAS for risk assessment to assist European Union policy implementation. We assess an unprecedented number of species with potential to harm EU biodiversity using a simple methodology and recommend which species should be considered for risk assessment in a ranked order of priority along the timeline 2018–2030, based on their maximum reported impact and their invasion history in Europe. [ABSTRACT FROM AUTHOR]

Risk assessment tools for listing invasive alien species need to incorporate all available evidence and expertise. Beyond the wealth of protocols developed to date, we argue that the current way of performing risk analysis has several shortcomings. In particular, lack of data on ecological impacts, transparency and repeatability of assessments as well as the incorporation of uncertainty should all be explicitly considered. We recommend improved quality control of risk assessments through formalized peer review with clear feedback between assessors and reviewers. Alternatively, a consensus building process can be applied to better capture opinions of different experts, thereby maximizing the evidential basis. Elaborating on manageability of invasive species is further needed to fully answer all risk analysis requirements. Tackling the issue of invasive species urges better handling of the acquired information on risk and the exploration of improved methods for decision making on biodiversity management. This is crucial for efficient conservation resource allocation and uptake by stakeholders and the public. [ABSTRACT FROM AUTHOR]

The amphibious plant species Crassula helmsii is a widely established and still-spreading alien in various parts of Europe, where it is considered invasive as its dense swards stress the viability of local biota. The species was considered to exclusively reproduce through vegetative means, until ex situ germination was recorded from a single locality in Belgium. We assessed whether this seed viability holds on a wider scale, by testing 16 populations from The Netherlands, Belgium, northern France, eastern England and northern Germany in a greenhouse germination experiment. Seedlings were observed from all populations but two, and from each of the five countries. Although most fruits were lacking seeds and the inferred germination percentages were overall low, germinable seed numbers are considerable given the high density of flowering stems. An in situ test revealed seeds to make it through normal winter conditions without signs of physical damage and with retention of germinability. Our results suggest that reproduction by seed is a relatively cryptic but widespread phenomenon throughout western Europe. The persistency of seed banks requires further investigation. Nonetheless, these findings already challenge the efficacy of techniques currently applied in C. helmsii control. [ABSTRACT FROM AUTHOR]

Plant communities are often dispersal-limited and zoochory can be an efficient mechanism for plants to colonize new patches of potentially suitable habitat. We predicted that seed dispersal by ungulates acts as an ecological filter - which differentially affects individuals according to their characteristics and shapes species assemblages - and that the filter varies according to the dispersal mechanism (endozoochory, fur-epizoochory and hoof-epizoochory). We conducted two-step individual participant data meta-analyses of 52 studies on plant dispersal by ungulates in fragmented landscapes, comparing eight plant traits and two habitat indicators between dispersed and non-dispersed plants. We found that ungulates dispersed at least 44% of the available plant species. Moreover, some plant traits and habitat indicators increased the likelihood for plant of being dispersed. Persistent or nitrophilous plant species from open habitats or bearing dry or elongated diaspores were more likely to be dispersed by ungulates, whatever the dispersal mechanism. In addition, endozoochory was more likely for diaspores bearing elongated appendages whereas epizoochory was more likely for diaspores released relatively high in vegetation. Hoof-epizoochory was more likely for light diaspores without hooked appendages. Fur-epizoochory was more likely for diaspores with appendages, particularly elongated or hooked ones. We thus observed a gradient of filtering effect among the three dispersal mechanisms. Endozoochory had an effect of rather weak intensity (impacting six plant characteristics with variations between ungulate-dispersed and non-dispersed plant species mostly below 25%), whereas hoof-epizoochory had a stronger effect (eight characteristics included five ones with above 75% variation), and fur-epizoochory an even stronger one (nine characteristics included six ones with above 75% variation). Our results demonstrate that seed dispersal by ungulates is an ecological filter whose intensity varies according to the dispersal mechanism considered. Ungulates can thus play a key role in plant community dynamics and have implications for plant spatial distribution patterns at multiple scales. [ABSTRACT FROM AUTHOR]

I H helix i and I H hibernica i share invasive characteristics, such as their evergreen leaves, persistence, and vegetative capabilities, but there are important ecological differences between the two species. Although both species are known to be problematic outside their natural ranges, invasive ivy populations consist more often of I H hibernica i than I H helix i , especially in forests (Clarke I et al i . 2006; Green I et al i . 2013). Triploid ivies have been found in co-occurring alien populations of I H helix i and I H hibernica i , suggesting they can hybridize, but to date no triploids have been found in Europe (Green I et al i . 2013). [Extracted from the article]

Given the large number of alien species that may potentially develop into invasives, there is a clear need for robust schemes that allow to screen species for such risks. The Harmonia framework presented here brings together 30 questions that refer to distinct components of invasion. Together, they cover the stages of introduction, establishment, spread, and multiple kinds of impacts, viz. referring to the health of the environment (including wild species), cultivated plants, domesticated animals and man. In a complete assessment, input is provided by choosing among predefined ordinal answers and by supplementing these with textual clarification. Uncertainty is covered by indicating levels of confidence. By converting answers into scores, which are then condensed into summary statistics, Harmonia allows for quantitative output on stage-specific and general risks. Test assessments on five species emerging in Belgium showed the perceived environmental risks of Procambarus clarkii to be highest (0.72), and that of Threskiornis aethiopicus to be lowest (0.13). Given the considerable parallels that exist between invasive alien species and emerging infectious diseases, we additionally created Pandora, which is a risk analysis scheme for pathogens and parasites. It consists of 13 key questions and has the same structure as Harmonia. Since diseases play a paramount role in biological invasions, results of Pandora assessments may feed into Harmonia through a slightly adapted, host-specific version named Pandora. Harmonia, Pandora and Pandora may be used both for prioritization purposes and for underpinning detailed risk analyses, and can be consulted online through . [ABSTRACT FROM AUTHOR]

Many herbaceous and graminoid plants from open communities are characterized by their relatively small size and by seeds that appear to lack any clear traits for dispersal. Such syndrome is likely the result of several selective pressures and their tradeoffs acting together. Drawing on the putative relationship of these plants with large mammals that graze on them, with respect to defoliation and the dispersal of seeds (endozoochory), we included plant stature as a trait in a simulation model to elaborate on these animals' relative contribution in plant evolution. Different configurations of the landscape were used as a template, as these are known to affect the response of plants through additional costs levied in dispersal. As such, two herbivore parameters (the intensity of grazing and the efficacy of endozoochorous dispersal) were tested along with two parameters of the landscape (the proportion and connectivity of suitable habitat). Plants were allowed to evolve freely under these conditions, assuming that taller plants 1) produce more seeds and 2) have a more distant seed rain in wind dispersal, but 3) are also more likely to suffer failed reproduction because of herbivory. Our model confirmed the effects of landscape on the resulting dispersal capacity of plants, although these effects were readily overruled by the actions of grazers. We found the evolution of plant size to primarily result from the effects of defoliation, but also (though to a lesser degree) from endozoochory. This provides support for the adaptive value of unassisted dispersal syndromes in plants. Endozoochory also succeeded in maintaining increased population densities. However, these effects only hold when grazers sustain a considerable transfer of seeds towards suitable plant habitat. [ABSTRACT FROM AUTHOR]

Many grassland plant species have limited capacity to disperse their seeds beyond local boundaries by natural means. Meanwhile, various forms of human transportation are observed to provide long-distance dispersal. However, the contribution of human-mediated dispersal to the spatial dynamics of established (meta)populations on the regional scale has only scarcely been addressed. Trifolium micranthum is a very small legume that is rare in western Belgium. It is found (i) inland, as a lawn weed on war cemeteries that are managed by the Commonwealth War Graves Commission, and (ii) in coastal grasslands that are managed for conservation. These stations lie over 30 km apart, though interestingly, a number of satellite war cemeteries are found within the vicinity of the coastal reserves, and these also harbor T. micranthum. We have sampled plants from these populations to study their affinities through genetic analysis (AFLP). Results indicated that the coastal cemetery populations were closely related to the inland cemeteries and not to the coastal reserves. This most likely is the result of exchange of seeds with composted lawn material among regions, whereas mowing machinery and livestock may effectuate frequent dispersal within regions. Assignment tests nonetheless indicated limited genetic admixture to have taken place at the coastal cemeteries. Thus, human management is responsible for the realization of gene flow among these remote gene pools. Human-mediated long-distance dispersal is likely to play a role in the local or regional dynamics of many other native plants, including more common and well-dispersing species. [ABSTRACT FROM AUTHOR]

Understanding the processes that determine genetic variation within landscapes is a crucial factor for successful management of threatened plant species that are sensitive to both environmental and genetic bottlenecks. While current insights point to the importance of historical landscape processes for the genetic structure of populations at large spatial scales, their relevance at small spatial scales has been largely neglected. In this context, coastal dunes are a typical example of dynamic and geologically young landscapes in which current and historical sand drift may have strong impacts on the spatial dynamics of a large number of plant species. One of these is the endangered plant species Parnassia palustris, typically inhabiting dune slacks formed by recent sand displacements in parabolic dune landscapes. Dune slacks originating from the same sand drift process are located within the same parabola unit. The species is known to suffer from dispersal limitation and from inbreeding when genetic exchange between populations is restricted. By means of amplified fragment length polymorphism, we demonstrate that the species shows a genetic substructuring both at the level of the metapopulation and the local landscape. Populations located within the same parabola unit are much more closely related than expected on the basis of geographic distance. Moreover, population size is related to genetic diversity within populations. The species' population genetic structure should consequently be regarded as a shifting mosaic of genetic variation, mediated by sand drift driven landscape formation. Therefore, the maintenance of sand dynamics is essential to preserve genetic diversity in dynamic dune landscapes. [ABSTRACT FROM AUTHOR]

Different species have different dispersal capabilities and in the field, species interact with each other within dynamic, heterogeneous and complex landscapes. While plants and certain herbivore species may disperse considerable distances by means of seed dispersal or flight, other herbivores (e.g. root-feeding nematodes or non-winged insect herbivores) are more limited in their dispersal capacities. This difference in dispersal capabilities results in mosaics of plant-herbivore interactions that shift over time and space leading to spatio-temporal variation in both the presence and absence of the species and their interactions. We developed an individual based simulation model in which we examined how multi-species interactions are affected by their mobility within structurally complex landscapes. The main objective was to address the consequences for the arms race between plant defence and herbivore resistance to changes in fundamental landscape and community attributes. We demonstrate that feedbacks between landscape structure, community structure and the specific dispersal rate of the species involved affect the evolutionary dynamics between plants and herbivore antagonists. While three-species interactions result in increased plant defence and herbivore resistance, effects of dispersal have diverse effects depending on the prevailing landscape structure. [ABSTRACT FROM AUTHOR]

Mature seeds of many legume species are normally characterized by water-impermeable seed coats, a form of physical dormancy. However, observations have suggested that the incidence of mature but permeable (non-dormant) seeds is sometimes substantial. Yet, the ecological processes associated with this non-dormancy have received little attention by plant ecologists. In white clover (Trifolium repens), we therefore studied: (1) the occurrence of initially permeable seeds in wild populations; (2) the relative performance of non-dormant and dormant seeds in plant establishment and reproduction in a field-sown experiment; and (3) the extent to which the trait is affected by humidity and plant genotype in a greenhouse experiment. No less than 35% of all viable seeds from the wild populations proved to be water permeable at maturity. The proportion of permeable seeds within inflorescences ranged from 0 to 100%. In the field-sown experiment, autumn-germinated non-dormant seeds had almost equally good chances of establishing as spring-germinated dormant seeds. Due to a marked head start in growth, the former yielded more flowers (and thus seeds) in the first flowering season. However, the greenhouse experiment proved that variation in the proportion of permeable seed between inflorescences represented a plastic response to humidity conditions during seed ripening, rather than variation among clones (broadsense heritability ≤ 0.025). Thus the trait is not easily subject to selection. [ABSTRACT FROM AUTHOR]