@article{VanKleunenWeberFischer2010,
  author    = {Van Kleunen, Mark and Weber, Ewald and Fischer, Markus},
  title     = {A meta-analysis of trait differences between invasive and non-invasive plant species},
  issn      = {1461-023X},
  year      = {2010},
  abstract  = {A major aim in ecology is identifying determinants of invasiveness. We performed a meta-analysis of 117 field or experimental-garden studies that measured pair-wise trait differences of a total of 125 invasive and 196 non-invasive plant species in the invasive range of the invasive species. We tested whether invasiveness is associated with performance-related traits (physiology, leaf-area allocation, shoot allocation, growth rate, size and fitness), and whether such associations depend on type of study and on biogeographical or biological factors. Overall, invasive species had significantly higher values than non-invasive species for all six trait categories. More trait differences were significant for invasive vs. native comparisons than for invasive vs. non-invasive alien comparisons. Moreover, for comparisons between invasive species and native species that themselves are invasive elsewhere, no trait differences were significant. Differences in physiology and growth rate were larger in tropical regions than in temperate regions. Trait differences did not depend on whether the invasive alien species originates from Europe, nor did they depend on the test environment. We conclude that invasive alien species had higher values for those traits related to performance than non-invasive species. This suggests that it might become possible to predict future plant invasions from species traits.},
  language  = {en}
}
@article{KhurooReshiMaliketal.2012,
  author    = {Khuroo, Anzar A. and Reshi, Zafar A. and Malik, Akhtar H. and Weber, Ewald and Rashid, Irfan and Dar, G. H.},
  title     = {Alien flora of India taxonomic composition, invasion status and biogeographic affiliations},
  series = {Biological invasions : unique international journal uniting scientists in the broad field of biological invasions},
  volume    = {14},
  journal   = {Biological invasions : unique international journal uniting scientists in the broad field of biological invasions},
  number    = {1},
  publisher = {Springer},
  address   = {Dordrecht},
  issn      = {1387-3547},
  doi       = {10.1007/s10530-011-9981-2},
  pages     = {99 -- 113},
  year      = {2012},
  abstract  = {The wide knowledge gaps in invasion biology research that exist in the developing world are crucial impediments to the scientific management and global policymaking on biological invasions. In an effort to fill such knowledge gaps, we present here an inventory of the alien flora of India, based on systematic reviews and rigorous analyses of research studies (ca. 190) published over the last 120 years (1890-2010 AD), and updated with field records of the last two decades. Currently, the inventory comprises of 1,599 species, belonging to 842 genera in 161 families, and constitutes 8.5\% of the total Indian vascular flora. The three most species-rich families are Asteraceae (134 spp.), Papilionaceae (114 spp.) and Poaceae (106 spp.), and the three largest genera are Eucalyptus (25 spp.), Ipomoea (22 spp.), and Senna (21 spp.). The majority of these species (812) have no report of escaping from cultivation. Of the remaining subset of 787 species, which have either escaped from intentional cultivation, or spread after unintentional introduction, casuals are represented by 57 spp., casual/naturalised by 114 spp., naturalised by 257 spp., naturalised/invasive by 134 spp., and invasive by 225 spp. Biogeographically, more than one-third (35\%) of the alien flora in India has its native ranges in South America, followed by Asia (21\%), Africa (20\%), Europe (11\%), Australia (8\%), North America (4\%); and cryptogenic (1\%). The inventory is expected to serve as the scientific baseline on plant invasions in India, with implications for conservation of global biodiversity.},
  language  = {en}
}
@article{KhurooWeberMaliketal.2011,
  author    = {Khuroo, Anzar A. and Weber, Ewald and Malik, A. H. and Reshi, Zafar A. and Dar, G. H.},
  title     = {Altitudinal distribution patterns of the native and alien woody flora in Kashmir Himalaya, India},
  series = {Environmental research},
  volume    = {111},
  journal   = {Environmental research},
  number    = {7},
  publisher = {Elsevier},
  address   = {San Diego},
  issn      = {0013-9351},
  doi       = {10.1016/j.envres.2011.05.006},
  pages     = {967 -- 977},
  year      = {2011},
  abstract  = {Background: Many studies have shown that alien species richness pattern follows that of native species richness patterns along environmental gradients, without taking the specific composition of the two groups into account. Objectives: To compare species richness patterns of native and alien woody plants along an altitudinal gradient in Kashmir Himalaya, India, and to analyse the specific composition, e.g. proportion of life forms. Methods: Analysis of secondary data from published floristic inventories. The gradient (500-4800 m asl) was split into 100 m bands and presence/absence data for each species were obtained, for each band. Results: Species richness of both native and alien species followed a hump-shaped distribution. Alien species richness dropped faster above 2000 m asl than the native did. The ratio of trees to shrubs decreased monotonically along the gradient in native species, but showed a peak at c. 2500 m asl in alien species. Alien species flowered in average earlier than native species. Conclusions: The change of species richness of native and alien species along altitude is similar, but the proportion of life forms is not. Most likely both climatic and socio-economic factors affect alien species richness and its specific composition in the Kashmir Himalaya.},
  language  = {en}
}
@unpublished{CierjacksKowarikJoshietal.2013,
  author    = {Cierjacks, Arne and Kowarik, Ingo and Joshi, Jasmin Radha and Hempel, Stefan and Ristow, Michael and von der Lippe, Moritz and Weber, Ewald},
  title     = {Biological flora of the british isles: robinia pseudoacacia},
  series = {The journal of ecology},
  volume    = {101},
  journal   = {The journal of ecology},
  number    = {6},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0022-0477},
  doi       = {10.1111/1365-2745.12162},
  pages     = {1623 -- 1640},
  year      = {2013},
  abstract  = {This account presents information on all aspects of the biology of Robinia pseudoacacia L. that are relevant to understanding its ecological characteristics and behaviour. 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 and conservation.Robinia pseudoacacia, false acacia or black locust, is a deciduous, broad-leaved tree native to North America. The medium-sized, fast-growing tree is armed with spines, and extensively suckering. It has become naturalized in grassland, semi-natural woodlands and urban habitats. The tree is common in the south of the British Isles and in many other regions of Europe.Robinia pseudoacacia is a light-demanding pioneer species, which occurs primarily in disturbed sites on fertile to poor soils. The tree does not tolerate wet or compacted soils. In contrast to its native range, where it rapidly colonizes forest gaps and is replaced after 15-30years by more competitive tree species, populations in the secondary range can persist for a longer time, probably due to release from natural enemies.Robinia pseudoacacia reproduces sexually, and asexually by underground runners. Disturbance favours clonal growth and leads to an increase in the number of ramets. Mechanical stem damage and fires also lead to increased clonal recruitment. The tree benefits from di-nitrogen fixation associated with symbiotic rhizobia in root nodules. Estimated symbiotic nitrogen fixation rates range widely from 23 to 300kgha(-1)year(-1). The nitrogen becomes available to other plants mainly by the rapid decay of nitrogen-rich leaves.Robinia pseudoacacia is host to a wide range of fungi both in the native and introduced ranges. Megaherbivores are of minor significance in Europe but browsing by ungulates occurs in the native range. Among insects, the North American black locust gall midge (Obolodiplosis robiniae) is specific to Robinia and is spreading rapidly throughout Europe. In parts of Europe, Robinia pseudoacacia is considered an invasive non-indigenous plant and the tree is controlled. Negative impacts include shading and changes of soil conditions as a result of nitrogen fixation.},
  language  = {en}
}
@article{HeinkenWeber2013,
  author    = {Heinken, Thilo and Weber, Ewald},
  title     = {Consequences of habitat fragmentation for plant species do we know enough?},
  series = {Perspectives in plant ecology, evolution and systematics},
  volume    = {15},
  journal   = {Perspectives in plant ecology, evolution and systematics},
  number    = {4},
  publisher = {Elsevier},
  address   = {Jena},
  issn      = {1433-8319},
  doi       = {10.1016/j.ppees.2013.05.003},
  pages     = {205 -- 216},
  year      = {2013},
  abstract  = {Habitat fragmentation is one of the most important causes for the decline of plant species. However, plants differing in phylogeny, habitat requirements and biology are likely to respond differently to habitat fragmentation. We ask whether case studies on the effects of habitat fragmentation conducted so far allow generalizations about its effects on the fitness and genetic diversity of populations of endangered plant species. We compared the characteristics of plant species endangered in Germany whose sensitivity to habitat fragmentation had been studied with those of the endangered species that had not been studied. We found strong discrepancies between the two groups with regard to their taxonomy and traits relevant to their sensitivity to habitat fragmentation. Monocots, graminoids, clonal, abiotically pollinated and self compatible species were underrepresented among the studied species, and most study species were from a few habitat types, in particular grasslands. We conclude that our current knowledge of the effects of habitat fragmentation on plant populations is not sufficient to provide widely applicable guidelines for species management. The selection of species studied so far has been biased toward species from certain habitats and species exhibiting traits that probably make them vulnerable to habitat fragmentation. Future studies should include community-wide approaches in different habitats, e.g. re-visitation studies in which the species pool is assessed at different time intervals, and population-biological studies of species from a wide range of habitats, and of different life forms and growth strategies. A more representative picture of the effects of habitat fragmentation would allow a better assessment of threats and more specific recommendations for optimally managing populations of endangered plants.},
  language  = {en}
}
@article{EsslDawsonKreftetal.2019,
  author    = {Essl, Franz and Dawson, Wayne and Kreft, Holger and Pergl, Jan and Pysek, Petr and van Kleunen, Mark and Weigelt, Patrick and Mang, Thomas and Dullinger, Stefan and Lenzner, Bernd and Moser, Dietmar and Maurel, Noelie and Seebens, Hanno and Stein, Anke and Weber, Ewald and Chatelain, Cyrille and Inderjit, and Genovesi, Piero and Kartesz, John and Morozova, Olga and Nishino, Misako and Nowak, Pauline M. and Pagad, Shyama and Shu, Wen-sheng and Winter, Marten},
  title     = {Drivers of the relative richness of naturalized and invasive plant species on Earth},
  series = {AoB PLANTS},
  volume    = {11},
  journal   = {AoB PLANTS},
  number    = {5},
  publisher = {Oxford Univ. Press},
  address   = {Oxford},
  issn      = {2041-2851},
  doi       = {10.1093/aobpla/plz051},
  pages     = {13},
  year      = {2019},
  abstract  = {Biological invasions are a defining feature of the Anthropocene, but the factors that determine the spatially uneven distribution of alien plant species are still poorly understood. Here, we present the first global analysis of the effects of biogeographic factors, the physical environment and socio-economy on the richness of naturalized and invasive alien plants. We used generalized linear mixed-effects models and variation partitioning to disentangle the relative importance of individual factors, and, more broadly, of biogeography, physical environment and socio-economy. As measures of the magnitude of permanent anthropogenic additions to the regional species pool and of species with negative environmental impacts, we calculated the relative richness of naturalized (= RRN) and invasive (= RRI) alien plant species numbers adjusted for the number of native species in 838 terrestrial regions. Socio-economic factors (per-capita gross domestic product (GDP), population density, proportion of agricultural land) were more important in explaining RRI (similar to 50 \% of the explained variation) than RRN (similar to 40 \%). Warm-temperate and (sub)tropical regions have higher RRN than tropical or cooler regions. We found that socio-economic pressures are more relevant for invasive than for naturalized species richness. The expectation that the southern hemisphere is more invaded than the northern hemisphere was confirmed only for RRN on islands, but not for mainland regions nor for RRI. On average, islands have similar to 6-fold RRN, and >3-fold RRI compared to mainland regions. Eighty-two islands (=26 \% of all islands) harbour more naturalized alien than native plants. Our findings challenge the widely held expectation that socio-economic pressures are more relevant for plant naturalization than for invasive plants. To meet international biodiversity targets and halt the detrimental consequences of plant invasions, it is essential to disrupt the connection between socio-economic development and plant invasions by improving pathway management, early detection and rapid response.},
  language  = {en}
}
@article{vanKleunenDawsonEssletal.2015,
  author    = {van Kleunen, Mark and Dawson, Wayne and Essl, Franz and Pergl, Jan and Winter, Marten and Weber, Ewald and Kreft, Holger and Weigelt, Patrick and Kartesz, John and Nishino, Misako and Antonova, Liubov A. and Barcelona, Julie F. and Cabezas, Francisco J. and Cardenas, Dairon and Cardenas-Toro, Juliana and Castano, Nicolas and Chacon, Eduardo and Chatelain, Cyrille and Ebel, Aleksandr L. and Figueiredo, Estrela and Fuentes, Nicol and Groom, Quentin J. and Henderson, Lesley and Inderjit, and Kupriyanov, Andrey and Masciadri, Silvana and Meerman, Jan and Morozova, Olga and Moser, Dietmar and Nickrent, Daniel L. and Patzelt, Annette and Pelser, Pieter B. and Baptiste, Maria P. and Poopath, Manop and Schulze, Maria and Seebens, Hanno and Shu, Wen-sheng and Thomas, Jacob and Velayos, Mauricio and Wieringa, Jan J. and Pysek, Petr},
  title     = {Global exchange and accumulation of non-native plants},
  series = {Nature : the international weekly journal of science},
  volume    = {525},
  journal   = {Nature : the international weekly journal of science},
  number    = {7567},
  publisher = {Nature Publ. Group},
  address   = {London},
  issn      = {0028-0836},
  doi       = {10.1038/nature14910},
  pages     = {100 -- +},
  year      = {2015},
  abstract  = {All around the globe, humans have greatly altered the abiotic and biotic environment with ever-increasing speed. One defining feature of the Anthropocene epoch(1,2) is the erosion of biogeographical barriers by human-mediated dispersal of species into new regions, where they can naturalize and cause ecological, economic and social damage(3). So far, no comprehensive analysis of the global accumulation and exchange of alien plant species between continents has been performed, primarily because of a lack of data. Here we bridge this knowledge gap by using a unique global database on the occurrences of naturalized alien plant species in 481 mainland and 362 island regions. In total, 13,168 plant species, corresponding to 3.9\% of the extant global vascular flora, or approximately the size of the native European flora, have become naturalized somewhere on the globe as a result of human activity. North America has accumulated the largest number of naturalized species, whereas the Pacific Islands show the fastest increase in species numbers with respect to their land area. Continents in the Northern Hemisphere have been the major donors of naturalized alien species to all other continents. Our results quantify for the first time the extent of plant naturalizations worldwide, and illustrate the urgent need for globally integrated efforts to control, manage and understand the spread of alien species.},
  language  = {en}
}
@article{SeebensEsslDawsonetal.2015,
  author    = {Seebens, Hanno and Essl, Franz and Dawson, Wayne and Fuentes, Nicol and Moser, Dietmar and Pergl, Jan and Pysek, Petr and van Kleunen, Mark and Weber, Ewald and Winter, Marten and Blasius, Bernd},
  title     = {Global trade will accelerate plant invasions in emerging economies under climate change},
  series = {Global change biology},
  volume    = {21},
  journal   = {Global change biology},
  number    = {11},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {1354-1013},
  doi       = {10.1111/gcb.13021},
  pages     = {4128 -- 4140},
  year      = {2015},
  abstract  = {Trade plays a key role in the spread of alien species and has arguably contributed to the recent enormous acceleration of biological invasions, thus homogenizing biotas worldwide. Combining data on 60-year trends of bilateral trade, as well as on biodiversity and climate, we modeled the global spread of plant species among 147 countries. The model results were compared with a recently compiled unique global data set on numbers of naturalized alien vascular plant species representing the most comprehensive collection of naturalized plant distributions currently available. The model identifies major source regions, introduction routes, and hot spots of plant invasions that agree well with observed naturalized plant numbers. In contrast to common knowledge, we show that the 'imperialist dogma,' stating that Europe has been a net exporter of naturalized plants since colonial times, does not hold for the past 60 years, when more naturalized plants were being imported to than exported from Europe. Our results highlight that the current distribution of naturalized plants is best predicted by socioeconomic activities 20 years ago. We took advantage of the observed time lag and used trade developments until recent times to predict naturalized plant trajectories for the next two decades. This shows that particularly strong increases in naturalized plant numbers are expected in the next 20 years for emerging economies in megadiverse regions. The interaction with predicted future climate change will increase invasions in northern temperate countries and reduce them in tropical and (sub) tropical regions, yet not by enough to cancel out the trade-related increase.},
  language  = {en}
}
@article{PyšekPerglEssletal.2017,
  author    = {Pyšek, Petr and Pergl, Jan and Essl, Franz and Lenzner, Bernd and Dawson, Wayne and Kreft, Holger and Weigelt, Patrick and Winter, Marten and Kartesz, John and Nishino, Misako and Antonova, Liubov A. and Barcelona, Julie F. and Cabezas, Francisco Jos{\´e} and C{\´a}rdenas L{\´o}pez, Dairon and C{\´a}rdenas-Toro, Juliana and Castańo, Nicol{\´a}s and Chac{\´o}n, Eduardo and Chatelain, Cyrille and Dullinger, Stefan and Ebel, Aleksandr L. and Figueiredo, Estrela and Fuentes, Nicol and Genovesi, Piero and Groom, Quentin J. and Henderson, Lesley and Inderjit, and Kupriyanov, Andrey and Masciadri, Silvana and Maurel, No{\"e}lie and Meerman, Jan and Morozova, Olʹga V. and Moser, Dietmar and Nickrent, Daniel and Nowak, Pauline M. and Pagad, Shyama and Patzelt, Annette and Pelser, Pieter B. and Seebens, Hanno and Shu, Wen-sheng and Thomas, Jacob and Velayos, Mauricio and Weber, Ewald and Wieringa, Jan J. and Baptiste, Maria P. and Kleunen, Mark van},
  title     = {Naturalized alien flora of the world},
  series = {Preslia : the journal of the Czech Botanical Society},
  volume    = {89},
  journal   = {Preslia : the journal of the Czech Botanical Society},
  number    = {3},
  publisher = {Czech Botanical Soc.},
  address   = {Praha},
  issn      = {0032-7786},
  doi       = {10.23855/preslia.2017.203},
  pages     = {203 -- 274},
  year      = {2017},
  abstract  = {Using the recently built Global Naturalized Alien Flora (GloNAF) database, containing data on the distribution of naturalized alien plants in 483 mainland and 361 island regions of the world, we describe patterns in diversity and geographic distribution of naturalized and invasive plant species, taxonomic, phylogenetic and life-history structure of the global naturalized flora as well as levels of naturalization and their determinants. The mainland regions with the highest numbers of naturalized aliens are some Australian states (with New South Wales being the richest on this continent) and several North American regions (of which California with 1753 naturalized plant species represents the world’s richest region in terms of naturalized alien vascular plants). England, Japan, New Zealand and the Hawaiian archipelago harbour most naturalized plants among islands or island groups. These regions also form the main hotspots of the regional levels of naturalization, measured as the percentage of naturalized aliens in the total flora of the region. Such hotspots of relative naturalized species richness appear on both the western and eastern coasts of North America, in north-western Europe, South Africa, south-eastern Australia, New Zealand, and India. High levels of island invasions by naturalized plants are concentrated in the Pacific, but also occur on individual islands across all oceans. The numbers of naturalized species are closely correlated with those of native species, with a stronger correlation and steeper increase for islands than mainland regions, indicating a greater vulnerability of islands to invasion by species that become successfully naturalized. South Africa, India, California, Cuba, Florida, Queensland and Japan have the highest numbers of invasive species. Regions in temperate and tropical zonobiomes harbour in total 9036 and 6774 naturalized species, respectively, followed by 3280 species naturalized in the Mediterranean zonobiome, 3057 in the subtropical zonobiome and 321 in the Arctic. The New World is richer in naturalized alien plants, with 9905 species compared to 7923 recorded in the Old World. While isolation is the key factor driving the level of naturalization on islands, zonobiomes differing in climatic regimes, and socioeconomy represented by per capita GDP, are central for mainland regions. The 11 most widely distributed species each occur in regions covering about one third of the globe or more in terms of the number of regions where they are naturalized and at least 35\% of the Earth’s land surface in terms of those regions’ areas, with the most widely distributed species Sonchus oleraceus occuring in 48\% of the regions that cover 42\% of the world area. Other widely distributed species are Ricinus communis, Oxalis corniculata, Portulaca oleracea, Eleusine indica, Chenopodium album, Capsella bursa-pastoris, Stellaria media, Bidens pilosa, Datura stramonium and Echinochloa crus-galli. Using the occurrence as invasive rather than only naturalized yields a different ranking, with Lantana camara (120 regions out of 349 for which data on invasive status are known), Calotropis procera (118), Eichhornia crassipes (113), Sonchus oleraceus (108) and Leucaena leucocephala (103) on top. As to the life-history spectra, islands harbour more naturalized woody species (34.4\%) thanmainland regions (29.5\%), and fewer annual herbs (18.7\% compared to 22.3\%). Ranking families by their absolute numbers of naturalized species reveals that Compositae (1343 species), Poaceae (1267) and Leguminosae (1189) contribute most to the global naturalized alien flora. Some families are disproportionally represented by naturalized aliens on islands (Arecaceae, Araceae, Acanthaceae, Amaryllidaceae, Asparagaceae, Convolvulaceae, Rubiaceae, Malvaceae), and much fewer so on mainland (e.g. Brassicaceae, Caryophyllaceae, Boraginaceae). Relating the numbers of naturalized species in a family to its total global richness shows that some of the large species-rich families are over-represented among naturalized aliens (e.g. Poaceae, Leguminosae, Rosaceae, Amaranthaceae, Pinaceae), some under-represented (e.g. Euphorbiaceae, Rubiaceae), whereas the one richest in naturalized species, Compositae, reaches a value expected from its global species richness. Significant phylogenetic signal indicates that families with an increased potential of their species to naturalize are not distributed randomly on the evolutionary tree. Solanum (112 species), Euphorbia (108) and Carex (106) are the genera richest in terms of naturalized species; over-represented on islands are Cotoneaster, Juncus, Eucalyptus, Salix, Hypericum, Geranium and Persicaria, while those relatively richer in naturalized species on the mainland are Atriplex, Opuntia, Oenothera, Artemisia, Vicia, Galium and Rosa. The data presented in this paper also point to where information is lacking and set priorities for future data collection. The GloNAF database has potential for designing concerted action to fill such data gaps, and provide a basis for allocating resources most efficiently towards better understanding and management of plant invasions worldwide.},
  language  = {en}
}
@article{DellingerEsslHojsgaardetal.2016,
  author    = {Dellinger, Agnes S. and Essl, Franz and Hojsgaard, Diego and Kirchheimer, Bernhard and Klatt, Simone and Dawson, Wayne and Pergl, Jan and Pysek, Petr and van Kleunen, Mark and Weber, Ewald and Winter, Marten and Hoerandl, Elvira and Dullinger, Stefan},
  title     = {Niche dynamics of alien species do not differ among sexual and apomictic flowering plants},
  series = {New phytologist : international journal of plant science},
  volume    = {209},
  journal   = {New phytologist : international journal of plant science},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0028-646X},
  doi       = {10.1111/nph.13694},
  pages     = {1313 -- 1323},
  year      = {2016},
  abstract  = {We compiled global occurrence data sets of 13 congeneric sexual and apomictic species pairs, and used principal components analysis (PCA) and kernel smoothers to compare changes in climatic niche optima, breadths and unfilling/expansion between native and alien ranges. Niche change metrics were compared between sexual and apomictic species. All 26 species showed changes in niche optima and/or breadth and 14 species significantly expanded their climatic niches. However, we found no effect of the reproductive system on niche dynamics. Instead, species with narrower native niches showed higher rates of niche expansion in the alien ranges. Our results suggest that niche shifts are frequent in plant invasions but evolutionary potential may not be of major importance for such shifts. Niche dynamics rather appear to be driven by changes of the realized niche without adaptive change of the fundamental climatic niche.},
  language  = {en}
}