Biological invasions are reportedly one of the major contributory factors to biodiversity loss worldwide. The impacts of invasive alien plant (IAP) species on native communities are widely documented in the scientific literature, however, there is still a lack of detailed information on their impacts within the most vulnerable habitats. Riparian habitats are highly dynamic systems and naturally disturbed, making them particularly vulnerable to invasion. Climate change, directly or indirectly, is also predicted to adversely impact river systems, which may subsequently alter invasion rates and the impacts of IAPs. However, the interactions between climate and IAPs and their combined effects on vegetation have rarely been examined. To address these knowledge gaps, this thesis investigates: (1) the role of environmental variables, such as sediment loading or climate-related changes to river flow regime, on the abundance of IAPs within riparian zones; (2) how variation in IAP abundance impacts native vegetation, relative to the effects of native dominant plant species and (3) some of the mechanisms underlying the effects of IAPs in riparian habitats. Historic and recent field survey data were used to investigate changes in riparian vegetation on British rivers during the last 20 years. Analyses indicate that IAPs had a negative but small effect on native plant diversity. Overall, changes in land use and differences in flow regime between recording periods were the most important predictors of plant community change. Specifically, IAPs had a greater probability of being present along lowland rivers that experienced increased frequency of high flow events. On a local scale across rivers in Scotland, the abundance of IAPs was constrained by greater soil moisture in summer, whilst greater abundance was associated with tree-lined banks. Both native dominant species and IAPs negatively affected subordinate species abundance to a greater extent than species richness, although this effect varied spatially with bank elevation. Artificial turf mats were used to quantify viable propagules within riverine sediment deposited over-winter along invaded riverbanks. The data indicate that there is a legacy effect of IAP abundance, with the most invaded sites being associated with higher sediment loading the following year, though, contrary to the general pattern, 12 sediment associated propagules were scarcer at invaded sites. Moreover, lower above-ground native diversity was associated with sites which had been previously invaded. Plant species composition in the propagule bank and above-ground vegetation were highly dissimilar, particularly closest to the water’s edge at highly invaded sites. This suggests that mono-specific stands of IAPs proliferate best under less disturbed environmental conditions, although fluvial disturbance events may be required to create opportunities for initial establishment. The propagule bank contributed very little to the above-ground vegetation, nor did it limit invasion, suggesting that above-ground plant composition is largely dictated by competitive interactions. The findings presented in this thesis suggest that invasion by IAPs is an additional stressor for native vegetation within riparian habitats, modifying above-ground plant communities via competition and suppressing recruitment from the propagule bank. However, native dominant species common in riparian habitats also negatively impact, subordinate species via competition, in some cases equalling the effect of IAPs. Native dominant and IAP species are differently affected by environmental factors operating in the riparian zone, which may provide future opportunities for reducing and managing invasions.

The aim of this thesis was to verify the success of previous reintroduction of noble crayfish (Astacus astacus) in main streams and selected reservoirs in the protected area Třeboňsko. Further expansion took place monitoring invasive signal crayfish (Pacifastacus leniusculus) and spiny cheek crayfish (Orconectes limosus) in these streams. Both are a carrier of crayfish plague. Thus, where they already exist, would not make sense to try to strengthen further the population of noble crayfish.

L’étude des mécanismes qui régissent le succès d’établissement et d’expansion des espèces exotiques apparait primordial pour l’appréhension de leurs potentiels impacts. Ce travail de thèse a pour objet d’étude la Perruche à collier \textit{Psittacula krameri}, un Psittacidé largement introduit en Europe. Les objectifs de ces travaux relèvent de l’étude des facteurs qui peuvent influencer le succès d’établissement de cette espèce en milieu urbain, par l’analyse de la sélection de l’habitat à l’étude des traits comportementaux. Les résultats montrent que la sélection de l’habitat est associée aux activités humaines, de par la préférence de l’espèce pour les zones urbanisées dans lesquelles l’espèce semble être attirée par les lumières artificielles et les espèces végétales exotiques. La comparaison de la sélection de l’habitat avec une espèce native en expansion, le Choucas des tours \textit{Corvus monedula}, a permis de montrer que la Perruche à collier est contrainte spatialement aux zones suburbaines tandis que le Choucas pourrait être capable de s’étendre aux zones les plus urbanisées. Une approche expérimentale et éthologique a mis en lumière le comportement agressif de la Perruche à collier et une monopolisation passive des ressources alimentaires, suggérant un avantage compétitif sur les espèces natives. L’ensemble des résultats de cette thèse laisse présager un potentiel de forte croissance démographique des populations et contribue aux connaissances nécessaires pour comprendre les mécanismes qui régissent l’établissement et le succès des espèces en expansion, native et exotique, tant au travers de l’étude spatiale que comportementale. / Identifying the mechanisms which may allow invasive species to establish and spread is not only a scientific question of interest but also a crucial knowledge to acquire for the management of these species. This thesis work focuses on the ring-necked parakeet, \textit{Psittacula krameri},, a Psittacine species widely introduced throughout Europe.This thesis aimed to study factors underlying the spatiotemporal distribution and which may explain the urban success of this species, from the analysis of habitat selection to behavioral traits. Results showed that habitat selection is closely related to anthropic activities, the species showing a clear preference for suburban zones and green urban areas in which the species seems to be attracted by artificial lights and exotic tree species. Using the Western jackdaw, a native range-expanding and co-occurring species, distribution modelling allowed to predict the potential future distribution and showed that, while the jackdaw may spatially expand in the more urbanized part of the city, the ring-necked parakeet may be restricted to suburban areas in the future. An ethological experiment highlighted the agonistic behavior of the ring-necked parakeet and a passive monopolization of resources, suggesting a competitive advantage over native species, exacerbated by temporal niche overlap and avoidance behavior by native species. This thesis suggests that parakeets have the potential to reach high numbers in urban areas and the overall findings provide further insight into the mechanisms allowing the establishment and spread of expanding species, native and exotic, through spatial and behavioral factors.

Made available in DSpace on 2016-12-12T20:12:27Z (GMT). No. of bitstreams: 1 PGEF13MA003.pdf: 12110 bytes, checksum: 7b1ae939feda74e5283da74e397a79bf (MD5) Previous issue date: 2013-10-04 / This study aimed to evaluate the biological invasion by tree species in two Araucaria Forest fragments (F1 and F2) in Lages, SC. A total of 25 plots were allocated in each fragment, distributed in five, 20x100 m, transects perpendicular to fragment edge and, at least, 100 m apart from each other, where the adult (individual with dbh diameter at breast height higher or equal to 5 cm) and the regenerative component (individuals belonging to tree species, with dbh lower than 5cm and height higher than 10 cm) were evaluated. All sampled individuals were identified and measured (circumference and height). For each fragment and component, the phytosociological descriptors and the biological invasion index (BII) were determined. The relationships between BII and the distance from the edge were evaluated by simple linear regressions. The grouping among non-native and native species was analyzed through spearman correlation and clusters. A total of 3,701 individuals distributed in 105 species and 42 families were sampled, being five invasive species: Citrus limon (L.) Burm, Ligustrum lucidum W.T. Aiton., Ligustrum sinense Lour., Pinus elliottii Engel. and Pinus taeda L. Myrtaceae was the richest family (22), with a total of 890 sampled individuals. In F1 occurred a relative low value of BII, with Pinus taeda as the most expressive species, being grouping with native pioneers species. The BII in F2 was elevated, mainly in the regenerative component, due to the expressive participation of Ligustrum lucidum (the most important species in this component). No relationships between BII and the distance from the edges were observed. The results demonstrated that the fragments showed different biological invasion patterns that were determined by the nature of surrounding matrix and the ecological traits of invasive species / O presente estudo teve como objetivo principal avaliar a invasão biológica por espécies arbóreas em dois fragmentos (F1 e F2) de Floresta Ombrófila Mista em Lages, SC. Foram alocadas 25 parcelas em cada fragmento, distribuídas em cinco transeções de 20x100 m, perpendiculares as bordas e com distância mínima de 100 m entre si, onde foram avaliados os componentes arbóreos adulto (indivíduos com DAP - diâmetro a altura do peito - maior ou igual a 5 cm) e regenerante (indivíduos pertencentes à espécies arbóreas com DAP menor que 5 cm e altura maior que 10 cm). Estes foram identificados e mensurados (circunferência e altura). Foi calculado, para cada estrato e para cada fragmento, os descritores fitossociológicos e o Índice de Invasão Biológica (IIB). A relação entre o IIB e a distância da borda foi verificada por meio de regressões lineares simples. O agrupamento de espécies exóticas e nativas foi determinada por meio de correlações de Spearman e a construção de dendrogramas. No total, foram amostrados 3.701 indivíduos distribuídos em 105 espécies e 42 famílias, sendo cinco espécies invasoras: Citrus limon (L.) Burm, Ligustrum lucidum W.T. Aiton., Ligustrum sinense Lour., Pinus elliottii Engel. e Pinus taeda L. A família Myrtaceae apresentou o maior número de espécies (22), com um total de 890 indivíduos amostrados. No F1 houve um valor de IIB relativamente baixo, sendo Pinus taeda a espécie com maior participação na invasão. O IIB no F2 foi alto, especialmente no estrato regenerativo, pela alta participação de Ligustrum lucidum (maior Índice de Regeneração Natural nesse estrato). Não foi observada relação entre a distância da borda e a intensidade da invasão biológica. Os resultados demonstraram que os fragmentos apresentaram diferentes padrões de invasão biológica, determinados pela natureza da matriz de entorno e pelas características ecológicas das espécies invasoras

The state of Florida has one of the most severe exotic species invasion problems in the United States, but little is known about their influence on soil biogeochemistry. My dissertation research includes a cross-continental field study in Australia, Florida, and greenhouse and growth chamber experiments, focused on the soil-plant interactions of one of the most problematic weeds introduced in south Florida, Lygodium microphyllum (Old World climbing fern). Analysis of field samples from the ferns introduced and their native range indicate that L microphyllum is highly dependent on arbuscular mycorrhizal fungi (AMF) for phosphorus uptake and biomass accumulation. Relationship with AMF is stronger in relatively dry conditions, which are commonly found in some Florida sites, compared to more common wet sites where the fern is found in its native Australia. In the field, L. microphyllum is found to thrive in a wide range of soil pH, texture, and nutrient conditions, with strongly acidic soils in Australia and slightly acidic soils in Florida. Soils with pH 5.5 - 6.5 provide the most optimal growth conditions for L. microphyllum, and the growth declines significantly at soil pH 8.0, indicating that further reduction could happen in more alkaline soils. Comparison of invaded and uninvaded soil characteristics demonstrates that L. microphyllum can change the belowground soil environment, with more conspicuous impact on nutrient-poor sandy soils, to its own benefit by enhancing the soil nutrient status. Additionally, the nitrogen concentration in the leaves, which has a significant influence in the relative growth rate and photosynthesis, was significantly higher in Florida plants compared to Australian plants. Given that L. microphyllum allocates up to 40% of the total biomass to rhizomes, which aid in rapid regeneration after burning, cutting or chemical spray, hence management techniques targeting the rhizomes look promising. Over all, my results reveal for the first time that soil pH, texture, and AMF are major factors facilitating the invasive success of L. mcirophyllum. Finally, herbicide treatments targeting rhizomes will most likely become the widely used technique to control invasiveness of L. microphyllum in the future. However, a complete understanding of the soil ecosystem is necessary before adding any chemicals to the soil to achieve a successful long-term invasive species management strategy.

Qui du phénomène de résistance (RA) ou de susceptibilité (SA) par association est prépondérant en milieu forestier ? En d’autres termes, la défoliation par les insectes herbivores est-elle moins (RA) ou plus (SA) importante sur des arbres hôtes situés en mélange comparés à des monocultures ? A cause des contraintes méthodologiques, les connaissances sur la relation diversité - résistance en forêts matures restent faibles. Pour répondre à cette question, nous avons utilisé le dispositif exploratoire du projet FunDivEUROPE. Sur un réseau de 209 parcelles forestières sélectionnées le long de deux gradients orthogonaux de richesse spécifique (d’une à cinq essences en mélange) et de latitude (de la forêt méditerranéenne à la boréale), nous avons évalué la défoliation des houppiers des arbres. A l’aide d’un échantillon constitué de onze essences différentes, nous avons démontré pour la première fois un patron global de diminution de l’herbivorie (RA) en forêts matures à travers l’Europe. Nous avons également comparé l’herbivorie des insectes dans des placettes constituées de chênes purs ou mélangés à d’autres espèces, placées en lisière ou à l’intérieur de petits bois présents dans les vallées et coteaux de Gascogne. Nous avons observé moins de dégâts foliaires sur les chênes entourés par des voisins hétérospécifiques, et nous avons montré que la magnitude de cette résistance (RA) était plus importante en lisière qu’à l’intérieur des bois. Enfin, nous avons testé cette hypothèse de RA sur une espèce d’herbivore invasif en Italie, le cynips du châtaignier. Basée sur la même approche méthodologique, notre étude a montré de plus faibles dégâts de galles sur les châtaigniers lorsque la richesse spécifique de la parcelle était élevée. Notre travail fournit donc de nouvelles preuves supportant l’hypothèse de RA à travers trois contributions originales : i) la RA existe en forêt mature, ii) quelle que soit l’espèce d’herbivore, iii) y compris sur des espèces exotiques. Ces résultats devraient avoir d’importantes implications pour la gestion des insectes herbivores en forêt puisque le maintien et l’amélioration de la diversité des essences représentent un outil prometteur pour prévenir les dégâts d’insectes. / Whether increasing forest diversity should result in less insect damage (Associational Resistance, AR) or more damage (Associational Susceptibility, AS) is still debated. Moreover little is known about the diversity - resistance relationships in mature forests due to methodological constraints. To answer this question we used the FundivEUROPE exploratory platform. In this network of 209 mature forest plots sampled along two orthogonal gradients of tree species richness (from one to five species mixtures) and latitude (from the Mediterranean to the boreal forest biomes), we assessed insect defoliation in tree crown. Focusing on eleven broadleaved species, we could for the first time demonstrate a global pattern of reduced defoliation (AR) in mature forests across Europe. We replicated the comparison of insect herbivory in pure vs. mixed plots of oak trees, at the edge or within forest patches of the valleys and hills of Gascony. Here we found significantly less damage on oaks surrounded by heterospecific neighbors, and showed that the magnitude of AR was larger at forest edge than in forest interiors. Last we tested the AR hypothesis with an invasive alien species, the Asian chestnut gall wasp, in Italy. Based on the same methodological approach, our study showed lower gall damage on chestnuts when tree species richness was higher in mixed mature stands. Our work therefore provide new evidences to support the AR hypothesis with three original contributions: i) AR does apply to mature forests, ii) irrespective of the identity of insect herbivores, iii) including exotic species. These findings may have important implications for pest management in forest since the maintenance or improvement of tree species diversity represent a promising tool to prevent insect damage.

La compréhension des mécanismes déterminant le succès des espèces invasives est une étape essentielle dans la gestion des invasions biologiques actuelles et la prédiction des futurs risques d’invasion. En adoptant un cadre d’étude conceptuel intégrant les processus écologiques et évolutifs, l’objectif de ce travail était d’analyser les déterminants de la colonisation de l’ambroisie à feuilles d’armoise en France. Tout d’abord, l’étude des interactions biotiques et abiotiques a permis de montrer la capacité de tolérance de l’ambroisie à l’herbivorie et au stress hydrique. L’ambroisie est capable de tolérer la défoliation grâce à une croissance compensatoire efficace, sans que sa reproduction en soit affectée. Cette forte tolérance à l’herbivorie est maintenue chez les populations introduites, malgré la faible pression des ennemis naturels dans la zone d’introduction. En condition de stress hydrique, l’ambroisie produit une biomasse racinaire supérieure aux espèces présentes dans les communautés qu’elle envahit. De plus, les différences dans les valeurs moyennes pour les traits mesurés suggèrent une occupation différente par l’ambroisie des niches écologiques disponibles. La comparaison en jardins communs de populations de l’aire d’origine avec des populations de l’aire d’introduction isolées et issues du foyer central d’invasion a montré que l’adaptation de l’ambroisie à son environnement reposait principalement sur la plasticité phénotypique plutôt que sur la différenciation des traits. Les études de génétiques quantitatives ont mis en évidence un potentiel évolutif élevé pour les traits liés à la germination. Les traits liés à la morphologie, à la phénologie et à la physiologie de la plante montrent une variance additive et une héritabilité plus faibles et donc un potentiel évolutif moindre. En revanche, la variation dans les normes de réaction indique un potentiel évolutif important de la plasticité phénotypique. La tolérance au stress hydrique et à l’herbivorie sont des facteurs qui potentiellement augmentent la capacité de l’ambroisie à coloniser une large gamme d’habitat. De plus, la plasticité phénotypique et le potentiel évolutif important peuvent favoriser une augmentation ou un déplacement de la niche écologique de l’espèce et ainsi favoriser l’expansion de son aire de répartition / Understanding of the mechanisms behind the success of the invasive species is essential to manage current biological invasions and to prevent the risks of the futures ones. Using a conceptual framework integrating ecological and evolutionary processes, this work aimed to analyse the factors of the common ragweed colonization in France. First of all, the study of biotic and abiotic interactions has shown the ability of common ragweed to tolerate herbivory and water stress. Common ragweed is able to buffer defoliation through an efficient compensatory growth with no consequence on the reproduction. Herbivory tolerance has been maintained in introduced populations even if herbivory pressure is low in the introduction area. Under water stress conditions, common ragweed displayed higher root biomass than the other species present in the communities it invades. In addition, differences in mean trait values suggest different niche occupation by common ragweed compared with its companion species. Common garden experiments comparing native populations vs. invasive isolated and invasive core populations have shown that adaptation ability is mainly due to phenotypic plasticity rather than trait differentiations. Quantitative genetic studies suggest a high evolutionary potential for germination traits. Morphological, phenological and physiological traits exhibit lower standard genetic variation and lower heritability and thus a lower evolutionary potential. However, variation in reaction norms suggests a high evolutionary potential for phenotypic plasticity. Herbivory and water stress tolerance are factors that potentially increase the ability to colonize à large range of habitats. Furthermore, phenotypic plasticity and evolutionary potential may also favour an increase or a shift in species ecological niche and hence may favour the distribution range expansion

<p>Climate change has dramatically altered the ecological landscape of the eastern U.S., leading to shifts in phenological events and redistribution of tree species. However, shifts in phenology and species distributions have implications for the productivity of different populations and <a></a>the communities these species are a part of. Here, I utilized two studies to quantify the effects of climate change on forests of the eastern U.S. First, I used phenology observations at a common garden of 28 populations of northern red oak (<i>Quercus rubra</i>) across seven years to assess shifts in phenology in response to warming, identify population differences in sensitivity to warming, and correlate sensitivity to the productivity of the populations. Second, I utilized data from the USDA Forest Service’s Forest Inventory and Analysis Program to identify forest communities of the eastern U.S., assess shifts in their species compositions and spatial distributions, and determine which climate-related variables are most associated with changes at the community level. In the first study, I found that populations were shifting their spring phenology in response to warming, with the greatest sensitivity in populations from warmer, wetter climates. However, these populations with higher sensitivity did not have the highest productivity; rather, populations closer to the common garden with intermediate levels of sensitivity had the highest productivity. In the second study, I found that there were 12 regional forest communities of the eastern U.S., which varied in the amount their species composition shifted over the last three decades. Additionally, all 12 communities shifted their spatial distributions, but their shifts were not correlated with the distance and direction that climate change predicted them to shift. Finally, areas with the highest changes across all 12 communities were associated with warmer, wetter, lower temperature-variable climates generally in the southeastern U.S. Taken together, these studies provide insight into the ways in which forests are responding to climate change and have implications for the management and sustainability of forests in a continuously changing global environment.</p>

Invasiva arter är ett stort hot mot den biologiska mångfalden världen över och den invasiva blomsterlupinen bidrar till minskad biodiversitet i de miljöer som den invaderar. Den är ett stort hot mot organismer i artrika infrastrukturmiljöer såsom artrika vägkanterna, vilka innehar en hög biologisk mångfald med hotade och sällsynta arter. I denna studie används GIS (Geografiskt informationssystem) för att undersöka blomsterlupinernas utbredning längsmed vägnätet i Jämtlands län. Resultatet visar att icke artrika vägkanter har en större andel vägkant med förekomst av blomsterlupiner än artrika vägkanter. Det finns ingen skillnad mellan artrika vägkanter med en bedömd högre värdeklass än artrika vägkanter med en bedömd lägre värdeklass vad gällande andelen vägkant med förekomst av blomsterlupiner. Att urskilja bakomliggande orsaker till det framkomna resultatet är problematiskt eftersom vägkanterna är heterogena miljöer som dessutom påverkas av många abiotiska och biotiska faktorer. Förekomsten av störningar snarare än biotisk resistens framhålls som tänkbar förklaring och utpekas som en inriktning för vidare forskning kring spridningen av blomsterlupiner inom vägnätet. / Invasive species are a major threat for biodiversity worldwide and the invasive Garden Lupine has shown to decrease biodiversity in the environments it invades. The invasion of Garden Lupines threatens infrastructure habitats, such as species rich road verges, which possess a high biodiversity with endangered and rare species. In this study, I used GIS (Geographic Information System) to investigate the spread of the Garden Lupine along the road network in the Swedish county of Jämtland. The result shows that non species-rich road verges have a larger proportion of road sections with occurrence of Garden Lupine than species rich road verges. A comparison between higher status species-rich road verges and lower status species rich road verges showed no difference in the proportion of the road section that contain Garden Lupine. Distinguishing the underlying causes to the result is problematic since road verges are heterogenic habitats under influence of a large variety of abiotic, biotic and anthropogenic factors. The presence of disturbances is a more likely explanation to the occurrence patterns than biotic resistance. This would also be a potential direction for further research concerning the spread of Garden Lupines along road verges.

Les invasions biologiques, deuxième cause de perte de biodiversité à l’échelle mondiale, représentent un risque majeur auquel nos sociétés doivent faire face. On parle d’invasion biologique lorsque des activités humaines permettent à une espèce de franchir des barrières qui jusqu’alors limitaient sa dispersion ou sa multiplication, entrainant une explosion géographique et démographique de l’espèce dans un nouvel écosystème et s’accompagnant éventuellement d’impacts économiques, sociétaux ou écologiques. La façon la plus efficace et la moins coûteuse de limiter les impacts causés par les espèces envahissante et de les prévoir en amont afin de mettre en place des mesures de prévention ciblées et efficaces et d’essayer de les éviter.L’objectif de cette thèse est de démontrer qu’il est possible d’améliorer la prédiction des invasions biologiques en développant et combinant différentes approches de modélisation de façon innovante. Les questions posées sont de savoir s’il est possible de prévoir quelles pourraient-être ces espèces, où elles pourraient devenir envahissantes et quels impacts elles pourraient avoir. Toutes les méthodes développées dans cette thèse ont été appliquées à des hyménoptères sociaux ; nombreuses espèces de fourmis (famille des Formicidés) ou frelon asiatique (famille des Vespidés, vespa Velutina nigrithorax), mais elles sont généralisables et réutilisables pour tout autre taxa.Je montre dans cette thèse qu’il est possible de développer un outil statistique de détection des espèces risquant de devenir envahissantes. J’applique cet outil aux fourmis, je fournis une liste de 15 espèces de fourmis risquant de devenir envahissantes à travers le monde et je cartographie les zones du globe risquant d’être envahies par ces espèces. Chacun des continents est menacée par au moins une de ces invasions potentielles. Dans un deuxième temps, je mets au point d’un cadre méthodologique permettant d’améliorer les prédictions d’aires de distribution des espèces en combinant leurs exigences climatiques et d’habitat, tout en respectant l’échelle géographique à laquelle ces facteurs agissent sur la distribution des espèces. J’applique cette méthode au frelon asiatique, ce qui me permet d’identifier les habitats qui lui sont les plus favorables et d’utiliser ces informations pour raffiner la prédiction de son aire favorable. En combinant le climat et l’habitat, je prédis une aire potentielle de distribution 56% plus restreinte par rapport aux estimations basées sur le climat uniquement. Enfin, dans un troisième temps, je m’intéresse au développement d’une méthode permettant de prédire spatialement les impacts causés par une invasion biologique. Pour ce faire, je prédis d’abord l’abondance potentielle du frelon asiatique en France. Je couple ensuite cette prédiction avec des données de présence de ruches et un modèle présidant l’impact du frelon asiatique sur la survie des colonies d’abeilles. J’estime enfin que cette invasion peut conduire à l’effondrement de 41% des colonies d’abeilles domestiques en France.Cette thèse met en lumière l’utilité d’intégrer la modélisation dans la construction du savoir autour des invasions biologiques, approche relativement nouvelle dans ce champ disciplinaire. De plus, elle illustre comment la modélisation et l’élaboration de prédictions peuvent aider à objectiver la prise de décision concernant la gestion des espèces envahissantes et optimiser leur efficacité en ciblant les habitats, les régions et les espèces d’action prioritaires. / Biologicals invasions, the second cause of biodiversity loss worldwide, represent a major threat that our societies have to face. Invasive species correspond to species that, due to human activities, cross geographic and reproduction barriers and expand into new areas in large numbers. This spread into new ecosystems may have severe socio-economic or ecological impacts. The most efficient way to limit these impacts is to predict and avoid biological invasions before they occur by setting up appropriate management plans.The aim of this PhD thesis is to demonstrate that existing predictive models can be further developed and combined together to improve biological invasion predictions. All of the methods developed in this thesis have been applied to social Hymenoptera: ant species (Formicidae) and the Asian hornet (Vespa velutina nigrithorax), but they are generalizable to any other taxa. The questions asked are: can we predict future invader species? Can we improve the spatial predictions of their distribution? Can we predict invasive species impact?First, I show in this thesis that it is possible to develop a model that detects future invasive species, even before they have had the chance to be moved outside their native range. I apply this screening tool to more than 2000 ant species, provide a list of the 15 ant species that are highly likely to become invasive and map their global suitability to highlights the area the most at risk from these invasions. All continents are threatened by at least one of these potential invasions. Second, I set up a methodological framework to improve species distribution predictions by combining multi-scale drivers. I apply this method to the invasive Asian hornet, identify its high affinity habitats, and use this information to refine suitability maps. I show that integrating multiple drivers, while still respecting their scale of effect, produced a potential range 55.9% smaller than that predicted using a climatic model alone. Finally, I propose a method to predict invasive species impacts in a spatially explicit way and I apply it to the estimate the Asian hornet’s impact on honeybee colonies in France. To do so, I estimate the Asian hornet nest density across France and combine it with an agent-based hive model to estimate honeybee mortality risk. I show that up to 41% of the honeybee colonies are likely to collapse due to the Asian hornet.Overall, these studies demonstrate how modelling techniques can provide valuable inputs to improve invasive species management decision by offering tools to optimize prevention strategies and target areas, species or habitats where action is needed in priority. Biological invasions involve our scientific, political and cultural perceptions in an intricate way; this PhD thesis highlights the usefulness of bringing together modelling techniques and the rest of biological invasion knowledge to better grasp invasion science complexity.