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Invasive alien species are one of the major threats to global biodiversity, ecosystem integrity, nature’s contribution to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in the future across spatial scales.Based on previous work on global invasion scenarios, we developed a workflow to downscale global scenarios to a regional and policy-relevant context. We applied this workflow at the European scale to create four European scenarios of biological invasions until 2050 that consider different environmental, socio-economic and socio-cultural trajectories, namely the European Alien Species Narratives (Eur-ASNs).We compared the Eur-ASNs with their previously published global counterparts (Global-ASNs), assessing changes in 26 scenario variables. This assessment showed a high consistency between global and European scenarios in the logic and assumptions of the scenario variables. However, several discrepancies in scenario variable trends were detected that could be attributed to scale differences. This suggests that the workflow is able to capture scale-dependent differences across scenarios.We also compared the Global- and Eur-ASNs with the widely used Global and European Shared Socioeconomic Pathways (SSPs), a set of scenarios developed in the context of climate change to capture different future socio-economic trends. Our comparison showed considerable divergences in the scenario space occupied by the different scenarios, with overall larger differences between the ASNs and SSPs than across scales (global vs. European) within the scenario initiatives.Given the differences between the ASNs and SSPs, it seems that the SSPs do not adequately capture the scenario space relevant to understanding the complex future of biological invasions. This underlines the importance of developing independent, but complementary, scenarios focused on biological invasions. The downscaling workflow we presented and implemented here provides a tool to develop such scenarios across different regions and contexts. This is a major step towards an improved understanding of all major drivers of global change including biological invasions.

Future dynamics of biological invasions are highly uncertain because they depend on multiple environmental, societal and socio-economic drivers. We adopted a qualitative scenario approach to explore the future of invasive alien species (IAS) in Europe and created an overall strategy for their management that considers different plausible future developments. The scenarios and strategy were developed during two online workshops with a multidisciplinary team of experts. First, we downscaled four global scenarios of biological invasions to the European level. Second, we developed a management strategy structured into 19 goals that cover a broad array of IAS-related topics (i.e. policy, research, public awareness and biosecurity), and provided solutions for achieving these goals considering the European scenarios. Third, we identified four interrelated recommendations around which any long-term strategy for managing IAS in Europe can be structured: (i) a European biosecurity regime, (ii) a dedicated communication strategy, (iii) data standardization and management tools, and (iv) a monitoring and assessment system. Finally, we identified the feasibility of the IAS management strategy, finding strong differences among the four scenarios. High levels of technological development, public environmental awareness, and effectiveness of IAS policies facilitated the implementation of the overall management strategy. Together, our results indicate that it is time for a new management of biological invasions in Europe based on a more integrative perspective across sectors and countries to be better prepared for future challenges.

International audience; Ambrosia trifida L. (giant ragweed, Asteraceae) is native to the North American continent and was introduced into Europe and Asia at the end of the 19th century. In its native range, this tall annual species is common in riparian and ruderal habitats and is also a major weed in annual cropping systems. For nearly a century, A. trifida has also been of great concern in the U.S. for its highly allergenic pollen, necessitating targeted control measures to reduce its impact on human populations. Based on the distribution of A. trifida in North America and in its introduced range, riparian systems in the rest of the world may be particularly at risk to invasion, with potential negative consequences for their biodiversity. Currently, A. trifida has invaded Asia more widely than Europe, likely due to the more favourable local conditions in Asia. Throughout its introduced range, A. trifida is host to a limited number of invertebrates and pathogens and only a few biological agents are available for its control. The main impacts of A. trifida at a global level are on crop yield and human health, resulting in significant socio-economic impacts. The success of A. trifida invasion in areas in which it has been introduced is still unclear, but climate change may increase climate suitability, increasing the potential for A. trifida to spread. While effective management in cultivated fields seems potentially possible, the development and control of A. trifida in natural riparian habitats is of great concern due to the difficulty of management in these areas.

Prioritizing the management of invasive alien species (IAS) is of global importance and within Europe integral to the EU IAS regulation. To prioritize management effectively, the risks posed by IAS need to be assessed, but so too does the feasibility of their management. While the risk of IAS to the EU has been assessed, the feasibility of management has not. We assessed the feasibility of eradicating 60 new (not yet established) and 35 emerging (established with limited distribution) species that pose a threat to the EU, as identified by horizon scanning. The assessment was carried out by 34 experts in invasion management from across Europe, applying the Non-Native Risk Management scheme to defined invasion scenarios and eradication strategies for each species, assessing the feasibility of eradication using seven key risk management criteria. Management priorities were identified by combining scores for risk (derived from horizon scanning) and feasibility of eradication. The results show eradication feasibility score and risk score were not correlated, indicating that risk management criteria evaluate different information than risk assessment. In all, 17 new species were identified as particularly high priorities for eradication should they establish in the future, whereas 14 emerging species were identified as priorities for eradication now. A number of species considered highest priority for eradication were terrestrial vertebrates, a group that has been the focus of a number of eradication attempts in Europe. However, eradication priorities also included a diverse range of other taxa (plants, invertebrates and fish) suggesting there is scope to broaden the taxonomic range of attempted eradication in Europe. We demonstrate that broad scale structured assessments of management feasibility can help prioritize IAS for management. Such frameworks are needed to support evidence-based decision-making. ispartof: GLOBAL CHANGE BIOLOGY vol:26 issue:11 pages:6235-6250 ispartof: location:England status: published

Spatbluhende Traubenkirsche: Waldpest oder Waldbaum, je nach Waldbaukontext Die aus dem ostlichen Teil von Nordamerika stammende Spatbluhende Traubenkirsche (Prunus serotina Ehrh. var. serotina) wurde und wird zum Teil noch immer von den europaischen Forstleuten als «Feind» wahrgenommen. In diesem Artikel zeigen wir die Geschichte der Art in den Niederlanden, Belgien, Deutschland sowie der Schweiz auf und gehen der Frage nach, wie stark die Art bei uns in Europa waldbauliche und okologische Ziele beeintrachtigt bzw. ob sie auch positive Wirkungen haben kann, zum Beispiel bei der Erfullung von Okosystemleistungen. Wir zeigen, dass je nach Kontext, in welchem sich Waldokologen und Waldbewirtschafter bewegen, die Antwort unterschiedlich ausfallen kann. Die in den vier genannten Landern gewonnenen Erkenntnisse machen deutlich, dass die konkrete Situation zu berucksichtigen ist, wenn die Notwendigkeit und die Moglichkeiten zur Integration dieser eingefuhrten und sich spontan ausbreitenden Art bewertet werden.

Eichhornia crassipes is notorious as the world’s worst aquatic weed, and here we present all aspects of its biology, ecology and invasion behaviour within the framework of the new series of Botany ...

When faced with a large species pool of invasive or potentially invasive alien plants, prioritization is an essential prerequisite for focusing limited resources on species which inflict high impacts, have a high rate of spread and can be cost-effectively managed. The prioritization process as detailed within this paper is the first tool to assess species for priority for risk assessment (RA) in the European Union (EU) specifically designed to incorporate the requirements of EU Regulation no. 1143/2014. The prioritization process can be used for any plant species alien to the EU, whether currently present within the territory or absent. The purpose of the prioritization is to act as a preliminarily evaluation to determine which species have the highest priority for RA at the EU level and may eventually be proposed for inclusion in the list of invasive alien species of EU concern. The preliminary risk assessment stage (Stage 1), prioritizes species into one of four lists (EU List of Invasive Alien Plants, EU Observation List of Invasive Alien Plants, EU List of Minor Concern and the Residual List) based on their potential for spread coupled with impacts. The impacts on native species and ecosystem functions and related ecosystem services are emphasized in line with Article 4.3(c) of the Regulation. Only those species included in the EU List of Invasive Alien Plants proceed to Stage 2 where potential for further spread and establishment coupled with evaluating preventative and management actions is evaluated. The output of Stage 2 is to prioritize those species which have the highest priority for a RA at the EU level or should be considered under national measures which may involve a trade ban, cessation of cultivation, monitoring, control, containment or eradication. When considering alien plant species for the whole of the EPPO region, or for species under the Plant Health Regulation, the original EPPO prioritization process for invasive alien plants remains the optimum tool.

Summary Ludwigia grandiflora (water primrose), a native to the Americas, is one of the most important invasive alien aquatic plants in Europe. In Germany, a first population was found in an oxbow lake of the River Leda in Lower Saxony, north-western Germany, in 2004. Ludwigia grandiflora formed both dense monospecific patches and mixed stands with native plants. A study on the biology of L. grandiflora documented that the plants regrow in spring from vegetative means only, even though viable seed production occurred. Hand weeding was successfully tested in different sampling sites as a sustainable management tool and subsequently used for the management of this species. Within 3 days, more than 99% of the biomass (25 tonnes of fresh mass) was harvested in 2013. Afterwards, a one-day post-treatment in the same year, two-one-day treatments in 2014 and one-one-day treatment in 2015 were made to harvest the regrown plants. After the first year, plant regrowth occurred only in one extremely muddy site, while in more than 99% of the water body, L. grandiflora was eradicated. Even though L. grandiflora was not completely eradicated from the water, a total eradication seems achievable within the next few years. The study documented the difficulties in the management of aquatic weeds, particularly in heterogeneous habitats with varying sediment structure. Management measures must be adapted to the infested habitat and species biology, which is mandatory for successful management of all aquatic weeds.

This account presents information on all aspects of the biology and ecology of Baccharis halimifolia L. that are relevant to understanding its invasive behaviour. The main topics are presented within the framework of the new series of Botany Letters on Monographs on invasive plants in Europe: taxonomy, distribution, history of introduction and spread, ecology (including preferred climate and habitats, responses to abiotic and biotic factors, ecological interactions), biology (including physiology, phenology and reproductive biology), impacts and management. Baccharis halimifolia L. (Asteraceae), groundsel bush, is a broad-leaved shrub native to the coastal area of southeastern North America. Introduced for ornamental and amenity purposes during the nineteenth century, it has become naturalized in several coastal habitats, as well as in disturbed areas of western Europe. The shrub is now common on the Atlantic coast of Europe from northern Spain to Belgium and it is an emerging problem on the Medit...

One of the EPPO (European and Mediterranean Plant Protection Organization) data sheets on pests recommended for regulation, being an output from the expert working group that risk assessed A. philoxeroides in April 2015.

Ambrosia artemisiifolia (ragweed) is a neophyte in Europe and Germany, which originated from the United States of America. In the USA the rate of sensitization against ragweed equals that of grass pollen, and without containment the rate of allergic sensitizations against ragweed pollen will clearly increase. Currently, the most frequent sensitizations in Germany are against grass pollen, followed by sensitizations against house dust mite and birch pollen. Ragweed pollen evokes symptoms at about 10 pollen/m3, grass pollen at about 15 pollen/m3. These concentrations of ragweed pollen are only reached on limited occasions in Germany. Ragweed cross-reacts with mugwort (Artemisia vulgaris) and a correct diagnosis is only feasible with the ragweed specific allergen Amb a 1. Due to cross reactivity with mugwort, new sensitizations against ragweed pollen are not needed to evoke allergic symptoms. The neophyte encounters an already mugwort-sensitized population, extends the pollen season and may provoke new sensitizations. Ragweed sensitizations are characterized by an increased tendency to also affect the lower airways, which is less with mugwort sensitizations. Thus containment of ragweed is needed. Ragweed seeds are imported or spread by contaminated bird feed, the transport of ragweed contaminated soil (also in tyre treads) and agricultural products from infested areas. States bordering on ragweed positive areas, like Brandenburg and Bavaria, are especially at risk and invasion is already underway. Ragweed seeds survive up to 40 years in soil, and so extended timescales for eradication and observations are needed. Germany is, compared to other countries like France (Rhone-Valley), Italy (Po-Valley), Ukraine and Hungary, limited in respect to ragweed infestation. Conditions in Germany are therefore favourable for the containment of ragweed. Switzerland implemented legislation against birdseed contamination by ragweed early during the plants expansion, and obligatory ragweed registration- and eradication showed that ragweed containment is possible. Without counter measures ragweed expansion in Germany will take place, resulting in more allergic disease. Considering the increasing number of allergic individuals, even without ragweed invasion, containment of the neophyte should be actively persued. Unfortunately, time is running out.

Ambrosia artemisiifolia (Ambrosia: Traubenkraut, Beifus-Ambrosie, englisch: „ragweed“) ist in Europa und Deutschland ein Neophyt, dessen Ursprung in den USA liegt. In den USA ist die allergische Sensibilisierung auf Ambrosia etwa gleich hoch wie fur Graserpollen, und ohne Gegenmasnahmen konnte auch in Deutschland die Zahl der Erkrankungen durch Ambrosia deutlich steigen. Zurzeit sind Sensibilisierungen durch Graserpollen in Deutschland am haufigsten, gefolgt von Sensibilisierungen durch Hausstaubmilben und Birkenpollen. Ambrosiapollen rufen Symptome ab etwa 10 Pollen/m3 hervor, Graserpollen bei etwa 15 Pollen/m3. Diese Konzentration an Ambrosiapollen wird momentan in den meisten Bundeslandern nur punktuell erreicht. Ambrosia (echte Ambrosie) zeigt Kreuzreaktivitaten mit Beifus (Artemisia vulgaris) und eine korrekte Diagnose ist nur mit dem ambrosiaspezifischen Allergen Amb a 1 moglich. Wegen der Kreuzreaktivitat mit Beifus sind neue Sensibilisierungen gegen Ambrosia nicht notwendig, um allergische Symptome auf Ambrosia hervorzurufen. Der Neophyt Ambrosia trifft auf eine bereits beifussensibilisierte Bevolkerung, verlangert die Pollensaison und kann neue Sensibilisierungen gegen Ambrosia hervorrufen. Die Ambrosiaallergie ist zusatzlich charakterisiert durch ein erhohtes Risiko zum „Etagenwechsel“, welcher bei einer Beifusallergie seltener vorkommt. Deswegen ist die Bekampfung von Ambrosia artemisiifolia notwendig. Ambrosiasamen werden uber verunreinigtes Vogelfutter und den Transport von Erde (auch im Profil von Autoreifen) und Agrarprodukten aus befallenen Gebieten verbreitet oder daraus eingeschleppt. Weil die Samen von Ambrosia bis zu 40 Jahre im Boden uberleben konnen, ist eine langfristige Bekampfung und Nachkontrolle notwendig. Im Vergleich zu Landern wie Frankreich (Rhone-Tal), Italien (Po-Ebene), Ukraine und Ungarn ist Deutschland in geringem Umfang von Ambrosia besiedelt. Daher besteht derzeit noch die Moglichkeit, eine weitere Ausbreitung mit relativ geringem Aufwand zu verhindern. Die Schweiz, in der bereits zu Beginn der Ambrosiaausbreitung gesetzliche Grundlagen zur Verhinderung einer weiteren Einschleppung sowie eine Melde- und Bekampfungspflicht eingefuhrt wurde, zeigt, dass es moglich ist, Ambrosia einzudammen. Ohne gezielte Gegenmasnahmen ist in Deutschland mit einer weiteren Ausbreitung von Ambrosia und damit zunehmenden Allergien zu rechnen. Aus Sicht der immer noch steigenden Anzahl an Allergikern in Deutschland sollte eine gezielte Bekampfung der Pflanze erfolgen. Viel Zeit bleibt aber nicht.

Thirty-seven alien plant species, pre-identified by horizon scanning exercises were prioritised for pest risk analysis (PRA) using a modified version of the EPPO Prioritisation Process designed to be compliant with the EU Regulation 1143/2014. In Stage 1, species were categorised into one of four lists – a Residual List, EU List of Minor Concern, EU Observation List and the EU List of Invasive Alien Plants. Only those species included in the latter proceeded to the risk management stage where their priority for PRA was assessed. Due to medium or high spread potential coupled with high impacts twenty-two species were included in the EU List of Invasive Alien Plants and proceeded to Stage 2. Four species (Ambrosia trifida, Egeria densa, Fallopia baldschuanica and Oxalis pes-caprae) were assigned to the EU Observation List due to moderate or low impacts. Albizia lebbeck, Clematis terniflora, Euonymus japonicus, Lonicera morrowii, Prunus campanulata and Rubus rosifolius were assigned to the residual list due to a current lack of information on impacts. Similarly, Cornus sericea and Hydrilla verticillata were assigned to the Residual List due to unclear taxonomy and uncertainty in native status, respectively. Chromolaena odorata, Cryptostegia grandiflora and Sphagneticola trilobata were assigned to the Residual List as it is unlikely they will establish in the Union under current climatic conditions. In the risk management stage, Euonymus fortunei, Ligustrum sinense and Lonicera maackii were considered a low priority for PRA as they do not exhibit invasive tendencies despite being widely cultivated in the EU over several decades. Nineteen species were identified as having a high priority for a PRA (Acacia dealbata, Ambrosia confertiflora, Andropogon virginicus, Cardiospermum grandiflorum, Celastrus orbiculatus, Cinnamomum camphora, Cortaderia jubata, Ehrharta calycina, Gymnocoronis spilanthoides, Hakea sericea, Humulus scandens, Hygrophila polysperma, Lespedeza cuneata, Lygodium japonicum, Pennisetum setaceum, Prosopis juliflora, Sapium sebiferum, Pistia stratiotes and Salvinia molesta).

Assessing the potential environmental impact of alien plants and plant pests is notoriously difficult. New protocols have been developed in the framework of the EC project PRATIQUE to provide guidance on environmental impact assessment in the EPPO pest risk analysis (PRA) decision-support scheme and enhance consistency between risk assessors and risk ratings for different pests. A set of questions with rating guidance and examples is provided, and individual scores are summarized into final scores, using a hierarchy of risk matrices, to assess current and potential environmental impacts. Two separate protocols are available: for alien plants and for other pests. These protocols could also be used to assess environmental impact in other PRA schemes as well as to assign alien species to regional black lists or to prioritize species for management decisions.

The EPPO Decision-support scheme (DSS) for Pest Risk Analysis (PRA) was fundamentally revised by the PRATIQUE EU project. Based on the examples of Polygonum perfoliatum (mile-a-minute-weed) and Eichhornia crassipes (water hyacinth), its applicability for invasive alien plants was tested. By means of a comparison of the risk analysis procedures with EPPO schemes before and after the project, pest group specific enhancements are outlined. For the two plants tested here, documented invasion history as well as biotic and abiotic requirements show that they can establish and spread in Europe and cause damage. PRATIQUE revisions to the EPPO DSS increased transparency, user friendliness and consistency for PRAs on invasive alien plants. This was accomplished through more comprehensive rating guidance, and aspects such as allowing individual risk elements to be documented and summarized to give a conclusive end result.

Although invasive alien plants are gaining increased attention within EPPO countries, there is no existing widely agreed method to identify those alien plants that are considered invasive and represent the highest priority for pest risk analysis. In the framework of the ad hoc Panel on Invasive Alien Species, EPPO proposes a prioritization process for invasive alien plants designed (i) to produce a list of invasive alien plants that are established or could potentially establish in the EPPO region and (ii) to determine which of these have the highest priority for an EPPO pest risk analysis. The process consists of compiling available information on alien plants according to pre-determined criteria, and can be run at the EPPO region level, or at a country or local area level. These criteria examine whether the species is alien in the area under study, and whether it is established or not. The criteria used primarily rely on observations in the EPPO region but, if the species is not established, the invasive behaviour of the species in other countries should be investigated, as well as the suitability of the ecoclimatic conditions in the area under consideration. The spread potential, the potential negative impacts on native species, habitats and ecosystems, as well as on agriculture, horticulture or forestry are considered. If the species qualifies as an invasive alien plant of major concern through this first set of questions, the process then investigates the efficiency of international measures (to be justified through a pest risk analysis) to prevent the entry and spread of the species. The second set of questions are designed to determine whether the species is internationally traded or enters new countries through international pathways for which the risk of introduction is superior to natural spread, and whether the species still has a significant suitable area for further spread. If used by several EPPO countries, this prioritization process represents an opportunity to provide consistent country lists of invasive alien plant species, as well as a tool for dialogue and exchange of information.

The International Plant Protection Convention (IPPC) provides the background for National Plant Protection Organisations (NPPOs) to regulate and control invasive alien species that are harmful to plants. This subject was specifically discussed for the first time 10 years ago at IPPC level, and further explored by an IPPC open-ended working group. The resulting concept was considered at EU level, and the EU Council supported the suitability of the plant health framework for these species, requesting the EU Commission to further analyse the needs for regulatory work in the EU plant health regime. Subsequently the European and Mediterranean Plant Protection Organization (EPPO) started a new working programme. The international conference ‘Invasive alien species and the IPPC’ set a signal for IPPC contracting parties to encourage their NPPOs to enforce actions on invasive alien species. IPPC standards on pest risk analysis (PRA) were adapted so as to include invasive alien species harmful to plants, and a memorandum of cooperation was adopted between the Secretariats of the IPPC and the Convention on Biological Diversity (CBD). At present, the EU Commission, DG Environment is developing a European strategy on invasive alien species. The EU Plant Health Regulatory System is currently subjected to a major evaluation process in which a clearer inclusion of invasive alien species into the system is one of the strategic discussions.

Prunus serotina, a forest tree of North American origin, was introduced to central Europe and planted for various purposes. In the course of the centuries it was regarded as a valuable timber tree by European foresters; subsequently, as a useful non-timber species in forestry, a forest pest, a controllable weed and, eventually, as a species we have to live with. All these perceived qualities served as motives for action by humans without seeking scientific evidence for them: millions of specimens of P. serotina were planted, later millions of euros were spent in attempts at control. The species, and its changing perception through time, may be an example of the need for science-based assessments as a basis for developing policies concerning non-native plants.

This account presents information on all aspects of the biology of Ambrosia artemisiifolia L. (Common ragweed) that are relevant to understanding its ecology. The main topics are presented within the standard framework of the Biological Flora of the British Isles: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, and history, conservation, impacts and management. Ambrosia artemisiifolia is a monoecious, wind-pollinated, annual herb native to North America whose height varies from 10 cm to 2.5 m, according to environmental conditions. It has erect, branched stems and pinnately lobed leaves. Spike-like racemes of male capitula composed of staminate (male) florets terminate the stems, while cyme-like clusters of pistillate (female) florets are arranged in groups in the axils of main and lateral stem leaves. Seeds require prolonged chilling to break dormancy. Following seedling emergence in spring, the rate of vegetative growth depends on temperature, but development occurs over a wide thermal range. In temperate European climates, male and female flowers are produced from summer to early autumn (July to October). Ambrosia artemisiifolia is sensitive to freezing. Late spring frosts kill seedlings and the first autumn frosts terminate the growing season. It has a preference for dry soils of intermediate to rich nutrient level. Ambrosia artemisiifolia was introduced into Europe with seed imports from North America in the 19th century. Since World War II, it has become widespread in temperate regions of Europe and is now abundant in open, disturbed habitats as a ruderal and agricultural weed. Recently, the North American ragweed leaf beetle (Ophraella communa) has been detected in southern Switzerland and northern Italy. This species appears to have the capacity to substantially reduce growth and seed production of A. artemisiifolia. In heavily infested regions of Europe, A. artemisiifolia causes substantial crop-yield losses and its copious, highly allergenic pollen creates considerable public health problems. There is a consensus among models that climate change will allow its northward and uphill spread in Europe.

The Editorial presents the focus, scope, policies, and the inaugural issue of NeoBiota, a new open access peer-reviewed journal of biological invasions. The new journal NeoBiota is a continuation of the former NEOBIOTA publication series. The journal will deal with all aspects of invasion biology and impose no restrictions on manuscript size neither on use of color. NeoBiota implies an XML-based editorial workflow and several cutting-edge innovations in publishing and dissemination, such as semantic markup of and enhancements to published texts, data publication, and extensive cross-linking within the journal and to external sources. Fil: Kühn, Ingolf. Helmholtz Centre for Environmental Research; Alemania Fil: Kowarik, Ingo. Technische Universität Berlin; Alemania Fil: Kollmann, Johannes. Technische Universitat München; Alemania Fil: Starfinger, Uwe. Julius Kuehn Institute; Alemania Fil: Bacher, Sven. University of Fribourg; Suiza Fil: Blackburn, Tim. King Saud University; Arabia Saudita Fil: Bustamante, Ramiro. Universidad de Chile; Chile Fil: Celesti Grapow, Laura. Università degli studi di Roma "La Sapienza"; Italia Fil: Chytrý, Milan. Masaryk University; República Checa Fil: Colautti, Robert. University of Duke; Estados Unidos Fil: Essl, Franz. Environment Agency Austria; Austria Fil: Foxcroft, Llewellyn. South African National Parks; Sudáfrica. Stellenbosch University; Sudáfrica Fil: García Berthou, Emili. University of Girona; España Fil: Gollasch, Stephan. GoConsult; Alemania Fil: Hierro, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina Fil: Hufbauer, Ruth. Colorado State University; Estados Unidos Fil: Hulme, Philip. Lincoln University; Estados Unidos Fil: Jarosik, Vojtech. Charles University in Prague; República Checa. Academy of Sciences of the Czech Republic; República Checa Fil: Jeschke, Jonathan. Ludwig Maximilians Universitat; Alemania Fil: Karrer, Gerhard. University of Natural Resources and Life Sciences Vienna; Austria Fil: Mack, Richard. Washington State University; Estados Unidos Fil: Molofsky, Jane. University of Vermont; Estados Unidos Fil: Murray, Brad. University of Technology Sydney; Australia Fil: Nentwig, Wolfgang. University of Bern; Suiza Fil: Osborne, Bruce. Universidad de Dublin; Irlanda Fil: Pysek, Petr. Charles University in Prague; República Checa. Academy of Sciences of the Czech Republic; República Checa Fil: Rabitsch, Wolfgang. Environment Agency Austria; Austria Fil: Rejmanek, Marcel. University of California at Davis; Estados Unidos Fil: Roques, Alain. Institut National de la Recherche Agronomique; Francia Fil: Shaw, Richard. CABI Europe; Reino Unido Fil: Sol, Daniel. Universitat Autònoma de Barcelona; España Fil: van Kleunen, Mark. Consejo Superior de Investigaciones Científicas; España Fil: Vilà, Montserrat. University of Konstanz; Alemania Fil: von der Lippe, Moritz. Technishe Universitat Berlin; Alemania Fil: Wolfe, Lorne. Georgia Southern University; Estados Unidos Fil: Penev, Lyubomir. Pensoft Publishers; Bulgaria

The sedentary habit is a major constraint for plants and has important ecological consequences. Rooted plants cannot escape their herbivorous enemies or other hazards and they interact and compete for light and other resources mostly with their close neighbors. Only clonal species have some limited possibilities to move from their natal site by creeping rhizomes, stolons, or roots. Dispersal patterns of seeds, movement of pollen, and to some limited extent clonal spread represent ways that allow migration of individuals or of genes through populations or into new populations. They represent clue events that cause not only the actual distribution of a given species but even more, on a smaller scale, they are responsible for the spatial and genetic structure of populations and subpopulations. Though dispersal patterns of plants have been of interest to naturalists for a long time, their ecological consequences in structuring populations and their role for gene flow and microevolutionary change are still poorly understood. The scope of this review is to cover recent literature that contributes to our understanding of the consequences of seed and pollen dispersal at the population and community level.

In Central Europe plant population ecology as a relatively young science is receiving more and more interest among ecologists. The recently published book on population ecology by Schmid and Stocklin (1991) and the textbook of Urbanska (1992), both in German, illustrate this. Studies with relevance for population ecology are being carried out with different contexts by scientists from different ecological fields. Inevitably, it was necessary in this review to observe certain limits. We treat important aspects of population ecology but do not pretend to cover all of its fields. The selection reflects our interest in how processes on the population level contribute to an understanding of processes on the vegetation level.

The Black Cherry (Prunus serotina), a North American forest tree, has successfully spread in Central Europe. By establishing dense shrub layers in previously sparse forests, it may outcompete native plant species and become a problem for nature conservation.

Myriophyllum heterophyllum presents an overall high phytosanitary risk for the EPPO region with a low uncertainty rating. The overall likelihood of M. heterophyllum continuing to enter the EPPO region is high. The plant is imported into the EPPO region as a misidentified aquatic species for aquaria and ponds and is already established in Austria, Belgium, France, Germany, Hungary, the Netherlands, Spain and Switzerland. The risk of entry into other EPPO countries through import is considered high. The risk of the species establishing in additional countries is high as movement through irrigation and river systems acts to connect countries, facilitating spread regionally. Spread may be accelerated by recreational activities in water bodies invaded by the weed. Impacts of the species within the EPPO region are likely to be severe (high score rating), including aquatic plant species displacement, habitat dominance and effects on other aquatic organisms.