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India has numerous invasive alien plant species (IAPSs), which seriously impact biodiversity, ecosystem services, and economic development. The availability of reliable occurrence records of IAPSs is of great importance for their successful management, prediction of distribution across time and space, and other research and development efforts. Global databases of occurrence data, like the Global Biodiversity Information Facility (GBIF), are often not exhaustive, especially for India, and poorly represent the actual distribution of IAPSs in the country. Our objective in creating this data set was threefold: (1) to compile occurrence data for the invasive and naturalized alien plant species of India, (2) to collect spatial and temporal information associated with occurrence records, and (3) to share the data in an accessible format so every record is traceable to its sources and allow users to submit data to increase the resolution of the data set. To achieve these objectives, we extracted data from 3137 literature records and 357 herbarium sheets. For each occurrence record, we curated information for 20 variables, which were arranged in a table with the Darwin Core (DwC) terms as column names. All data were subjected to technical validation before being included in the database. A total of 12,347 occurrence records were obtained for 362 species (195 invasive aliens and 167 naturalized aliens). The number of collected occurrence records was much higher for the invasive aliens (73.7%) than for the naturalized alien species (26.3%). Our data set will supplement the GBIF data by 60.39%, and occurrence records will be added for 64 invasive and naturalized alien plant species. The data set, as a part of the larger database of the Indian Alien Flora Information (ILORA) database, is made available without any restrictions on use as long as this data paper is properly cited. We have also made provisions for users to submit occurrence-related data following a data standard. The users are encouraged to cite the original reference when using a specific data record. The data set is expected to assist a wide range of stakeholders involved in India's scientific research, policy formulation, and decision-making related to IAPSs., (© 2022 The Authors. Ecology © 2022 The Ecological Society of America.)

Background: In the field of biological invasions science, a problem of many overlapping terms arose among eradication assessment frameworks. Additionally there is a need to construct a universally applicable eradication evaluation system. To unify the terminology and propose an eradication feasibility assessment scale we created the Unified System for assessing Eradication Feasibility (USEF) as a complex tool of factors for the analysis of eradications of alien (both invasive and candidate) plant species. It compiles 24 factors related to eradication success probability reported earlier in the literature and arranges them in a hierarchical system (context/group/factor/component) with a possibility to score their influence on eradication success., Methodology: After a literature survey we analyzed, rearranged and defined each factor giving it an intuitive name along with the list of its synonyms and similar and/or related terms from the literature. Each factor influencing eradication feasibility is ascribed into one of four groups depending on the context that best matches the factor: location context (size and location of infestation, ease of access), species context (fitness and fecundity, detectability), human context (knowledge, cognition and resources to act) and reinvasion context (invasion pathways). We also devised a simple ordinal scale to assess each factor's influence on eradication feasibility., Conclusions: The system may be used to report and analyze eradication campaign data in order to (i) prioritize alien species for eradication, (ii) create the strategy for controlling invasive plants, (iii) compare efficiency of different eradication actions, (iv) find gaps in knowledge disabling a sound eradication campaign assessment. The main advantage of using our system is unification of reporting eradication experience data used by researchers performing different eradication actions in different systems., Competing Interests: The authors declare there are no competing interests., (©2022 Galera et al.)

When analyzing biotic resistance/diversity-invasibility, including predictors of species richness may result in a false negative correlation between native and non-native richness. However, reanalysis of vegetation surveys shows that the negative effect of native richness is statistically significant whether or not predictors of species richness are included., (© 2021 John Wiley & Sons Ltd.)

As drivers of global change, biological invasions have fundamental ecological consequences. However, it remains unclear how invasive plant effects on resident animals vary across ecosystems, animal classes, and functional groups. We performed a comprehensive meta-analysis covering 198 field and laboratory studies reporting a total of 3624 observations of invasive plant effects on animals. Invasive plants had reducing (56%) or neutral (44%) effects on animal abundance, diversity, fitness, and ecosystem function across different ecosystems, animal classes, and feeding types while we could not find any increasing effect. Most importantly, we found that invasive plants reduced overall animal abundance, diversity and fitness. However, this significant overall effect was contingent on ecosystems, taxa, and feeding types of animals. Decreasing effects of invasive plants were most evident in riparian ecosystems, possibly because frequent disturbance facilitates more intense plant invasions compared to other ecosystem types. In accordance with their immediate reliance on plants for food, invasive plant effects were strongest on herbivores. Regarding taxonomic groups, birds and insects were most strongly affected. In insects, this may be explained by their high frequency of herbivory, while birds demonstrate that invasive plant effects can also cascade up to secondary consumers. Since data on impacts of invasive plants are rather limited for many animal groups in most ecosystems, we argue for overcoming gaps in knowledge and for a more differentiated discussion on effects of invasive plant on native fauna., (© 2015 John Wiley & Sons Ltd.)

Montane regions worldwide have experienced relatively low plant invasion rates, a trend attributed to increased climatic severity, low rates of disturbance, and reduced propagule pressure relative to lowlands. Manipulative experiments at elevations above the invasive range of non-native species can clarify the relative contributions of these mechanisms to montane invasion resistance, yet such experiments are rare. Furthermore, global climate change and land use changes are expected to cause decreases in snowpack and increases in disturbance by fire and forest thinning in montane forests. We examined the importance of these factors in limiting montane invasions using a field transplant experiment above the invasive range of two non-native lowland shrubs, Scotch broom (Cytisus scoparius) and Spanish broom (Spartium junceum), in the rain-snow transition zone of the Sierra Nevada of California. We tested the effects of canopy closure, prescribed fire, and winter snow depth on demographic transitions of each species. Establishment of both species was most likely at intermediate levels of canopy disturbance, but at this intermediate canopy level, snow depth had negative effects on winter survival of seedlings. We used matrix population models to show that an 86% reduction in winter snowfall would cause a 2.8-fold increase in population growth rates in Scotch broom and a 3.5-fold increase in Spanish broom. Fall prescribed fire increased germination rates, but decreased overall population growth rates by reducing plant survival. However, at longer fire return intervals, population recovery between fires is likely to keep growth rates high, especially under low snowpack conditions. Many treatment combinations had positive growth rates despite being above the current invasive range, indicating that propagule pressure, disturbance, and climate can all strongly affect plant invasions in montane regions. We conclude that projected reductions in winter snowpack and increases in forest disturbance are likely to increase the risk of invasion from lower elevations., (© 2014 John Wiley & Sons Ltd.)

Invasion science is a very active subdiscipline of ecology. However, some scientists contend that theoretical integration has been limited and that predictive power remains weak. This paper, focusing on plants, proposes a new multi-pronged research strategy that builds on recent advances in invasion science. More intensive studies on particular model organisms and ecosystems are needed to improve our understanding of the full suite of interacting factors that influence invasions ('model system research'). At the same time, comparative studies across many study systems are essential for unravelling the context-dependencies of insights that emerge from particular studies ('multi-site studies'); and quantitative synthesis based on large datasets should be constrained to well-defined theoretical domains ('focused meta-analysis'). We also suggest ways for better integration of information about species biology and ecosystem characteristics ('invasion syndromes'). We expect that a resulting theory of invasions will need to be conceived as a somewhat heterogeneous conglomerate of elements of varying generality and predictive power: laws that apply to well-specified domains, general concepts and theoretical frameworks that can guide thinking in research and management, and in-depth knowledge about the drivers of particular invasions., (© 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.)

Non‐native annual grasses can dramatically alter fire frequency and reduce forage quality and biodiversity in the ecosystems they invade. Effective management techniques are needed to reduce these undesirable invasive species and maintain ecosystem services. Well‐timed management strategies, such as grazing, that are applied when invasive grasses are active prior to native plants can control invasive species spread and reduce their impact; however, anticipating the timing of key phenological stages that are susceptible to management over vast landscapes is difficult, as the phenology of these species can vary greatly over time and space. To address this challenge, we created range‐wide phenology forecasts for two problematic invasive annual grasses: cheatgrass (Bromus tectorum), and red brome (Bromus rubens). We tested a suite of 18 mechanistic phenology models using observations from monitoring experiments, volunteer science, herbarium records, timelapse camera imagery, and downscaled gridded climate data to identify the models that best predicted the dates of flowering and senescence of the two invasive grass species. We found that the timing of flowering and senescence of cheatgrass and red brome were best predicted by photothermal time models that had been adjusted for topography using gridded continuous heat‐insolation load index values. Phenology forecasts based on these models can help managers make decisions about when to schedule management actions such as grazing to reduce undesirable invasive grasses and promote forage production, quality, and biodiversity in grasslands; to predict the timing of greatest fire risk after annual grasses dry out; and to select remote sensing imagery to accurately map invasive grasses across topographic and latitudinal gradients. These phenology models also have the potential to be operationalized for within‐season or within‐year decision support. [ABSTRACT FROM AUTHOR]

In response to non‐native plant invasions, many governments have established noxious weed lists to control and eradicate introduced invasive plants. However, invasive agronomic species are often unregulated, and the extent of their invasion across habitat types has never been determined.Using vegetation surveys across 222 plots, we investigated the contribution of agronomic versus noxious non‐native species to the levels of invasion across seven habitat types in central Canada.Although agronomic non‐native species, such as Poa pratensis and Bromus inermis, only made up 21.3% of the non‐native species pool, they accounted for 43.6% of non‐native plant species frequency and 74.4% of relative non‐native plant cover. They were also disproportionately overrepresented compared with noxious non‐native species across all habitat types, except saline marshes.The overabundance of agronomic non‐native plants in central Canada is likely the legacy of cultivar breeding, intentional seeding of introduced forage species and a lack of incentive for the use of native species.Synthesis and applications: Decelerating the invasion by agronomic non‐native plants will require approaches beyond noxious weed lists and initiatives in research, policy and education. These tools can include incentives to use native seed material, for example, in reclamation and forage and turf production, to reduce propagule pressure from invasive agronomic non‐native plants. [ABSTRACT FROM AUTHOR]

Species introduced from elsewhere are known as alien species. They may be introduced as crop plants or ornamental plants, or for timber. A small proportion of introduced species can become invasive thereby spreading at the cost of native species and habitats, negatively affecting biodiversity, food security, and human wellbeing. Despite the growing recognition of the threat of invasive alien species, we still lack information about the distribution and abundance of species widely accepted to be invasive. To address this information gap regarding invasive alien species distributions, we initiated a pilot citizen science effort to create an atlas of invasive plants in the Moyar-Bhavani landscape of the Nilgiri District. We aimed, through this pilot effort, to develop and test user-friendly mapping protocols and develop an interface for citizen scientists to use. Ultimately, we hope to create a model that can be scaled up to large conservation landscapes, such as the Western Ghats, the Central Indian Highlands, and the Himalaya. [ABSTRACT FROM AUTHOR]

The Andes mountain range in South America has a high level of endemism and is a major source of ecosystem services. The Andes is increasingly threatened by anthropogenic disturbances that have allowed the establishment of non-native plants, mainly in the lower elevation areas. However, synergies between climate change and anthropogenic pressure are promoting the spread of non-native plants to higher elevation areas. In this article, we evaluate and identify the main non-native plants invading Andean ecosystems, and assess their taxonomic families, growth forms and distribution patterns. Based on a systematic literature review, we identified the importance of climatic and anthropogenic factors as drivers of non-native species establishment in Andean ecosystems and the main impacts of non-native plants in the Andes. We then identified research gaps across each biogeographic region in the Andes. Finally, we highlight key elements to better tackle the problem of non-native plant invasions in Andean ecosystems, including the need for a systematic monitoring of invasion patterns and spread (e.g. MIREN protocol) and a common policy agenda across international borders for the prevention and management of non-native plants in this highly vulnerable region. [ABSTRACT FROM AUTHOR]

To serve human needs, non-native species are selected based on an array of functional traits, which generally confer competitive advantages to these species in their recipient environments. Identifying non-obvious functional traits that indirectly inform human selection of non-natives to introduce into urban greenspaces is not yet part of common discussions in invasion biology. We tested whether functional traits integrated within a phylogenetic framework, may reveal those subtle criteria underlying the introduction of non-native plants into urban greenspaces. We found no differences in terms of functional traits between natives and non-natives. We also found no evidence that functional traits predict nectar production, irrespective of how nectar production was measured. Finally, we found that the mean sugar concentration of nectar per flower is evolutionarily shared both within closely related non-native plants as well as within close native plants. However, phylogenetically close species share similar intraspecific variation in mass of nectar sugar per flower, but this is true only for non-native plants, thus revealing a non-obvious selection criteria of non-native plants for urban greenspaces. Our results indicate that the phylogenetic patterns of intraspecific variation in mass of nectar sugar per flower is the major criterion distinguishing non-natives from native plants in urban greenspaces in Southern England. [ABSTRACT FROM AUTHOR]

Introduced plants can have long-lasting and irreversible effects on the communities and ecosystems they invade. A critical step towards understanding the legacy of plant introductions is the characterisation of changes in the invaded plant communities and how these changes are related to biogeochemical modifications. Here, we addressed this issue by comparing the impacts of two large invasive herbs, Gunnera tinctoria and Impatiens glandulifera, on the compositional, functional, and phylogenetic structure of the standing vegetation (above-ground communities) and the soil seed bank (below-ground communities). The introduction of both invasive species was associated with a significant decrease in above-ground species richness, with subsequent changes in the functional diversity and phylogenetic dispersion of the vegetation. Yet, these invaders differed in their long-term impacts and the reversibility of any modifications they caused. While G. tinctoria invasions resulted in phylogenetically clustered communities (both above and below-ground) that were clearly distinct from uninvaded ones, seed bank communities invaded by I. glandulifera were indistinguishable from uninvaded ones, despite major compositional changes above-ground. Further, we found alterations in nutrient cycling associated with G. tinctoria invasions that could facilitate its local persistence and exacerbate any negative effects on native diversity. Our findings suggest a high susceptibility of pre-invasion above-ground communities to colonisation by distantly related herbs. However, the seed banks showed a degree of resilience against both invaders, with no major differences in species richness. Ultimately, differences in the impacts of these large invasive herbs suggest that dominance in the vegetation and a large stature are poor predictors of long-term plant community changes, including regeneration potential from seed, which are associated with plant introductions. [ABSTRACT FROM AUTHOR]

Although relatively infrequent, invasions by non-native plants at high latitudes are increasingly recognized as an emerging problem. Churchill, MB, Canada is unusual as over 100 non-native species have been found in human-disturbed areas, making it an outlier amongst subarctic habitats. Although these non-native species have persisted almost exclusively within town, some occur in isolated locations throughout the local road network. Most of these non-native species have been observed in areas with a history of soil movement (e.g., for construction or road repairs), suggesting that they have been moved within the soil, likely either germinating from seeds or growing clonally from root and rhizome fragments. Using a greenhouse experiment, we found evidence that soils from human-disturbed sites can contain a substantial non-native seed bank. In particular, we grew a significantly higher number of non-native seedlings from translocated soils compared with uninvaded soils. These germinated non-native species are native to Europe but have widely invaded temperate regions. This study provides the first direct evidence that movement of seed-contaminated soil is a significant source of local non-native species spread. Future warming in Arctic regions may increase seed production of these species, leading to increased spread and persistence via contaminated soil. [ABSTRACT FROM AUTHOR]

The negative impacts of non‐native species have been well documented, but some non‐natives can play a positive role in native ecosystems. One way that non‐native plants can positively interact with native butterflies is by provisioning nectar. Relatively little is known about the role of phenology in determining native butterfly visitation to non‐native plants for nectar, yet flowering time directly controls nectar availability. Here we investigate the phenological patterns of flowering by native and non‐native plants and nectar foraging by native butterflies in an oak savanna on Vancouver Island, British Columbia, Canada. We also test whether native butterflies select nectar sources in proportion to their availability. We found that non‐native plants were well integrated into butterfly nectar diets (83% of foraging observations) and that visitation to non‐natives increased later in the season when native plants were no longer flowering. We also found that butterflies selected non‐native flowers more often than expected based on their availability, suggesting that these plants represent a potentially valuable resource. Our study shows that non‐native species have the potential to drive key species interactions in seasonal ecosystems. Management regimes focused on eradicating non‐native species may need to reconsider their aims and evaluate resources that non‐natives provide. [ABSTRACT FROM AUTHOR]

Many invasion hypotheses propose biotic interactions as the main mechanism to explain non‐native species' success. Despite the evidence that the strength of biotic interactions varies with abiotic context, it remains unclear whether the importance of the different mechanisms proposed to explain invasion predictably varies with the abiotic context and whether this variation is consistent across different growth forms.We reviewed studies at a global scale to evaluate whether evapotranspiration, latitude, precipitation and temperature influence the importance of disturbance, enemy release, facilitation, and novel weapons mechanisms to explain non‐native plant invasions. In total, we calculated 171 effect sizes for ~300 non‐native plant species covering a wide range of environmental conditions and growth forms.Environmental context and plant growth form influenced the role played by each invasion mechanism. The importance of disturbance in facilitating invasion exhibited a quadratic relationship with latitude and temperature, and decreased with increasing precipitation. In mixed communities and trees, disturbance was mediated by either evapotranspiration, latitude, precipitation or temperature. Enemy release exhibited a quadratic relationship with evapotranspiration, latitude and precipitation, and it was positively related to temperature. The importance of enemy release was also contingent on growth form and was highly context‐dependent. Enemy release responses for grasses, and trees were modulated by either evapotranspiration, latitude, precipitation or temperature. The importance of facilitation decreased with increasing temperature. In forbs, facilitation decreased with evapotranspiration and temperature. The importance of novel weapons was more strongly confirmed for studies conducted at lower evapotranspiration, precipitation and higher latitudes, and exhibited a quadratic relationship with temperature.Synthesis. Our results show that environmental conditions not only filter non‐native species depending on physiological tolerances but may also influence the importance of invasion mechanisms. [ABSTRACT FROM AUTHOR]

Efficient management of invasive species benefits from understanding patterns of persistence and change over time. In this study, we compare distribution and abundance of the invasive macrophyte parrotfeather (Myriophyllum aquaticum) in an unregulated river system between the time near its presumed introduction and 20 years later. Initial surveys were conducted in 1996–1997, and were repeated in 2015–2016 using similar methodology. Moderate increases in the proportion of river kilometers with parrotfeather between the two periods were observed, but the distribution of sites with low, medium, and high abundance remained consistent, with small numbers of sites in either period having well-established extents of parrotfeather. The distributional extent has moved downstream, with the most upstream and downstream presences shifted by 17 and 28 river kilometers, respectively; however, parrotfeather remains sparse in the lower reaches below the historical downstream extent. Sites with high abundance and stable presence over time are in the intermediate segment of the river, indicating longitudinal and hydrologic controls on distribution. In contemporary sites, area of parrotfeather cover was associated with larger, deeper habitats, whereas dominance of parrotfeather occurred in smaller sites having uniformly shallow depth and low bank slopes. Sites where both abundance and dominance were low had dense canopy cover. Our results demonstrate that landscape and site-level characteristics restrict establishment and persistence of parrotfeather, and that hydrologic alterations to stabilize flow regimes and land use changes should be considered for their potential to increase presence of parrotfeather and other invasive aquatic plants in dynamic floodplain habitats. [ABSTRACT FROM AUTHOR]

Biological invasions are one of the most defining features of the Anthropocene. Most studies on biological invasions focus on the later stages of the invasion process, that is after species have already become naturalized. It is frequently overlooked, however, that patterns in origin, phylogeny and traits of naturalized alien species might largely reflect which species have been introduced in the first place. Here, we quantify and assess such introduction biases by analyzing 5317 plant species introduced for cultivation (i.e. primarily as ornamental garden plants) in the 10 countries composing Southern Africa. We show that this cultivated alien flora represents a non‐random subset of the global flora and that this bias at the introduction stage largely contributes to patterns in geographic origin, phylogenetic composition and traits of the naturalized flora. For example, while species from Australasia are, compared to the global flora, disproportionally overrepresented in the naturalized cultivated flora of Southern Africa, this pattern is driven by their higher likelihood of introduction for cultivation. The same is true for the overrepresentation of free‐standing woody species in the naturalized cultivated flora. The strong phylogenetic clustering of the naturalized cultivated flora is also, to a large extent, driven by introduction bias. Although functional traits explained little variation in naturalization success of cultivated plants, naturalization success was more likely for plants with intermediate seed mass and height and high specific leaf area. Thus, despite strong biases in which species have been introduced to Southern Africa, there are significant patterns in the species characteristics related to naturalization probability. Our quantification of introduction biases demonstrates that they are huge, and that accounting for it is important to avoid over‐ or under‐emphasizing the characteristics of successfully naturalized alien plants. [ABSTRACT FROM AUTHOR]

Since 2007, more people in the world live in urban than in rural areas. The development of urban areas has encroached into natural forest ecosystems, consequently increasing the ecological importance of parks and fragmented forest remnants. However, a major concern is that urban activities have rendered urban forests susceptible to non-native species incursions, making them central entry sites where non-native plant species can establish and spread. We have little understanding of what urban factors contribute to this process. Here we use data collected by citizen scientists to determine the differential impacts of spatial and urban factors on non-native plant introductions in urban forests. Using a model city, we mapped 18 urban forests within city limits, and identified all the native and non-native plants present at those sites. We then determined the relative contribution of spatial and socioeconomic variables on the richness and composition of native and non-native plant communities. We found that socioeconomic factors rather than spatial factors (e.g., urban forest area) were important modulators of overall or non-native species richness. Non-native species richness in urban forest fragments was primarily affected by residential layout, recent construction events, and nearby roads. This demonstrates that the proliferation of non-native species is inherent to urban activities and we propose that future studies replicate our approach in different cities to broaden our understanding of the spatial and social factors that modulate invasive species movement starting in urban areas. [ABSTRACT FROM AUTHOR]

Resources for biodiversity conservation are limited and it is therefore imperative that management actions that have the best chance of success are prioritized. Non‐native species (NNS) are one of the key problems facing biodiversity conservation, so understanding how NNS disperse and establish can inform more effective conservation planning and management. Using a novel Bayesian belief network model, we investigated non‐native plant dispersal on the approximately 550 islands along the Pilbara coast, Western Australia, and identified priority species and locations for targeted management. Of a total of around 9,000 weed arrivals onto the islands, 1,661 arrivals across 14 weed species had some probability of establishment. Suggested management actions in these cases would be education campaigns to inform visitors about the risk of accidental transport of propagules, quarantine programs, and eradication. For the seven weed species that arrived only via human dispersal and had a >10% chance of establishment on five islands, surveillance, and control of new arrivals would be the recommended management actions. Removal of propagule source populations would not be a cost‐effective management strategy. The inherent flexibility of our model means that different objectives can be analyzed in a transparent way, making it a powerful tool for guiding effective targeted action, derived from an explicit decision‐making framework. [ABSTRACT FROM AUTHOR]

Aim: Biological invasion has become one of the most important environmental concerns in many countries, with considerable time, money and effort being spent in the prevention and eradication of invasive species. Since mineral ores tend to harbour seeds from the local plants, our aim was to study the non‐native plants collected in Chinese ports to understand the influence of global ore trade on biological invasion. Location: China. Methods: We surveyed 75 ore heaps across six types of ore in 22 Chinese port cities from 2010 to 2016 and collected 737 voucher specimens of non‐native plants, out of which 709 specimens were traced to the country of origin. Using the software Maxent, we evaluated the risk of invasion from these non‐native plants based on the global ore trade flow, traced their route and predicted the regions in China most vulnerable to invasion by these plants. Results: Of the 407 non‐native plant species identified, most were from India, followed by Malaysia, Swaziland, Mexico, and Iran. Taxonomically, there were representations from 49 families, notably Fabaceae, Poaceae, Asteraceae and Solanaceae. The non‐native plant species were represented by varying number of species, from a single specimen to 179. Analysis of the invasion risk indicated that the entire coast of China was at high risk. Furthermore, two major potential introduction pathways were also identified, namely the Yangtze drainage basin and the land from the Gulf of Tonkin to Sichuan Basin. Main conclusion: An important pathway for the invasion of non‐native plants is the inadvertent transportation of seeds through global ore trade networks. Based on this study, we suggest greater monitoring and cooperation in the international ore trade for better management, and creating public awareness of the dangers of non‐native species to help minimize the risk of transporting non‐native plants by the global ore trade network. [ABSTRACT FROM AUTHOR]

Most invasive plants have been originally introduced for horticultural purposes. Still, most alien garden plants have not naturalized yet, probably due in part to inadequate climatic conditions. Climate change may alter this, but few experimental studies have addressed this for non‐naturalized alien garden plants, and those that have, addressed only singular aspects of climate change.In a greenhouse experiment, we examined the performance of nine non‐naturalized alien herbaceous garden plants of varying climatic origins in response to simulated climate warming and reduced water availability, in a factorial design, as projected for southern Germany. To assess their invasion potential, we grew the species in competition with resident native and already‐naturalized alien species.Reduced watering negatively affected non‐naturalized garden plants, as well as the native and naturalized competitors, particularly at higher temperatures. However, non‐naturalized aliens performed better relative to competitors when temperatures increased. Naturalized and native resident competitor responses to climate change were both negative, but across climate treatments, non‐naturalized aliens, irrespective of their climatic origins, performed better against native than against naturalized competitors.Synthesis. We conclude that relative performance compared to resident species may increase for non‐naturalized alien garden plants under climate change, as resident species become less competitive. Ongoing climate change is therefore likely to promote naturalization of commonly planted alien herbaceous species. [ABSTRACT FROM AUTHOR]

A definitive list of invasive species traits remains elusive, perhaps due to inconsistent ways of identifying invasive species. Invasive species are typically identified using one or more of four demographic criteria (local abundance, geographic range, environmental range, spread rate), referred to here as the demographic dimensions of invasiveness., In 112 studies comparing invasive and non-invasive plant traits, all 15 combinations of the four demographic dimensions were used to identify invasive species; 22% of studies identified invasive species solely by high abundance, while 25% ignored abundance., We used demographic data of 340 alien herbs classified as invasive or non-invasive in Victoria, Australia, to test whether the demographic dimensions are independent and which dimensions influence invasive species listing in practice., Species' abundances, spread rates and range sizes were independent. Relative abundance best explained the invasiveness classification. However, invasive and non-invasive species each spanned the full range of each demographic dimension, indicating that no dimension clearly separates invasive from non-invasive species., Graminoids with longer minimum residence times were more frequently classified as invasive, as were forbs occurring near edges of native vegetation fragments., Synthesis. Conflating multiple forms of invasiveness, by not distinguishing invasive species that are identified using different demographic criteria, may obscure traits possessed by particular subsets of invasive species. Traits promoting high abundance likely differ from those enabling fast spread and broad ranges. Examining traits linked with the four demographic dimensions of invasiveness will highlight species at risk of becoming dominant, spreading quickly or occupying large ranges. [ABSTRACT FROM AUTHOR]

[Display omitted] • Non-native plants mainly shifted upward, while native plants shifted downward. • The upper limit of both native and non-native plants showed different trends. • Non-native plants expanded their elevational range size, native plants shrank. • The climate suitability and change in upper/lower limits influence species' shifts. Species are changing their elevational distributions in response to climate change, leading to biodiversity loss and changes in community structure. Yet whether native and non-native species have consistent elevational shifts remains to be evaluated. Subtropical mountains are rich in biodiversity, sensitive to climate change, and are experiencing high risks of biological invasion. Hence exploring the changes in species elevational distributions induced by climate change in subtropical mountains is an urgent need. Here, we explored the impact of climate change on the elevational distribution of seed plant species in Jinfo Mountain (Mt. Jinfo), a subtropical mountain in China with rich plant diversity. Notably, we compared the elevational redistributions of native and non-native plants in response to climate change. The results showed that the elevational centroids of native plant species moved downhill, while those of non-native plants shifted upward on average. The upper limit of native plants shifted downward, while the upper limit of non-native plants shifted upward on average. The elevational shifts of non-native plants were dominated by changes in the upper range limits, while those of native plants were affected by the lower limits. These opposite elevational shifts of native vs non-native species led to the increase in the elevational range size of the non-native plants, but decrease in the elevational range size of native plants, especially in high altitudes. The differences in the directions and magnitudes of elevational shifts between the native and non-native plants are mainly due to differences in their climate adaptation. Changes in temperature and precipitation influenced the elevational range shifts of native plants but not of non-native ones. This study provides a new perspective for understanding the elevational redistribution of native and non-native plant species in subtropical mountains, and suggests that climate change has stronger influence on native than non-native species. [ABSTRACT FROM AUTHOR]

Prevention and early detection are considered to be the most effective means of managing non-native invasive species that have serious ecological and economic impacts. Consequently, the study of those taxa that are still in an early stage of invasion but are highly likely to spread and to have a significant adverse impact in future is becoming an increasingly important issue in both the research on and management of invasive species. In Italy, one such species isArctotheca calendula(L.) Levyns, a herbaceous plant of theAsteraceaefamily that is native to South Africa. Here, we present an overview of current knowledge on the distribution and potential impacts of this species in Italy, and we outline some features that are crucial to understanding and preventing its invasive spread. [ABSTRACT FROM PUBLISHER]

Aim Use of local-scale non-native plant species ( NNS) distribution models has the potential to decrease survey effort and improve population prioritization for management. We developed and evaluated data collection methods and minimum sampling requirements to inform local-scale models of NNS distribution. We also evaluated overall model predictive performance for 16 species at two sites and determined how classes of variables contributed to model performance and suggest invasion drivers. Location Wyoming and Idaho, USA Methods A simulation study was used to test the efficiency of different sampling methods to predict imposed species distributions. Empirical distribution models of species occurrence data from two environmentally disparate sites were cross-validated at increasing sample sizes, and the asymptotic maximum predictive performance and relative contribution of classes of variables were determined for 16 NNS. Results Transect sampling was the most efficient method for maximizing model performance after accounting for logistics. Minimum sample sizes to reach model maximum predictive performance were similar for the simulation (< 0.5% of study area) and empirical studies (mean of 0.13% using transects). Maximum predictive performance tended to be greater at the site with steeper environmental gradients, and topo-climatic/biotic variables were most important to model improvement. Main conclusions Local-scale SDMs can be useful to NNS managers. Using transect methodology, enough data can be collected (ca. 0.13% of the management area) to fit models within logistical/budgetary constraints. These models are most predictive for well-established species as opposed to new invaders and in areas with steeper environmental gradients. Finally, topo-climatic/biotic predictors are the most important variables for predicting more established species, but disturbance and dispersal limitation should be considered and quantified to ensure variables associated with dominant processes are included in the SDM. [ABSTRACT FROM AUTHOR]

Background and Aims Invasiveness of some alien plants is associated with their traits, plastic responses to environmental conditions and interpopulation differentiation. To obtain insights into the role of these processes in contributing to variation in performance, we compared congeneric species of Impatiens (Balsaminaceae) with different origin and invasion status that occur in central Europe. Methods Native I. noli-tangere and three alien species (highly invasive I. glandulifera, less invasive I. parviflora and potentially invasive I. capensis) were studied and their responses to simulated canopy shading and different nutrient and moisture levels were determined in terms of survival and seedling traits. Key Results and Conclusions Impatiens glandulifera produced high biomass in all the treatments and the control, exhibiting the ‘Jack-and-master’ strategy that makes it a strong competitor from germination onwards. The results suggest that plasticity and differentiation occurred in all the species tested and that along the continuum from plasticity to differentiation, the species at the plasticity end is the better invader. The most invasive species I. glandulifera appears to be highly plastic, whereas the other two less invasive species, I. parviflora and I. capensis, exhibited lower plasticity but rather strong population differentiation. The invasive Impatiens species were taller and exhibited higher plasticity and differentiation than native I. noli-tangere. This suggests that even within one genus, the relative importance of the phenomena contributing to invasiveness appears to be species'specific. [ABSTRACT FROM PUBLISHER]

ABSTRACT Aim To determine relative effects of habitat type, climate and spatial pattern on species richness and composition of native and alien plant assemblages in central European cities. Location Central Europe, Belgium and the Netherlands. Methods The diversity of native and alien flora was analysed in 32 cities. In each city, plant species were recorded in seven 1-ha plots that represented seven urban habitat types with specific disturbance regimes. Plants were classified into native species, archaeophytes (introduced before ad 1500) and neophytes (introduced later). Two sets of explanatory variables were obtained for each city: climatic data and all-scale spatial variables generated by analysis of principal coordinates of neighbour matrices. For each group of species, the effect of habitat type, climate and spatial variables on variation in species composition was determined by variation partitioning. Responses of individual plant species to climatic variables were tested using a set of binomial regression models. Effects of climatic variables on the proportion of alien species were determined by linear regression. Results In all cities, 562 native plant species, 188 archaeophytes and 386 neophytes were recorded. Proportions of alien species varied among urban habitats. The proportion of native species decreased with increasing range and mean annual temperature, and increased with increasing precipitation. In contrast, proportions of archaeophytes and neophytes increased with mean annual temperature. However, spatial pattern explained a larger proportion of variation in species composition of the urban flora than climate. Archaeophytes were more uniformly distributed across the studied cities than the native species and neophytes. Urban habitats rich in native species also tended to be rich in archaeophytes and neophytes. Main conclusions Species richness and composition of central European urban floras are significantly affected by urban habitat types, climate and spatial pattern. Native species, archaeophytes and neophytes differ in their response to these factors. [ABSTRACT FROM AUTHOR]

Abstract: Invasion of some alien plants is considered to be associated with inter-population differentiation and adaptations to local conditions. To obtain an insight into these processes it is convenient to compare invasive plants with their native congeners. The intra-specific differentiation during invasion was studied using four Impatiens (Balsaminaceae) species in Central Europe: native Impatiens noli-tangere and three aliens (highly invasive Impatiens glandulifera, less invasive Impatiens parviflora and potentially invasive Impatiens capensis). Differentiation in traits important for the establishment (germination; seedling emergence; seedling frost resistance) was measured in a laboratory and an experimental garden using seed collected from five natural populations of each species. Frost resistance of I. capensis, currently invasive in Western Europe, was within the scope of other congeners and it does not seem to be a barrier to spread of the species into Central Europe. Among-population differences were found within all species except I. capensis. In I. noli-tangere, I. glandulifera and I. parviflora the differences were related to the climatic characteristics in early spring at the source localities, which indicates that individuals may be adapted to local conditions. The differences found between the populations of I. noli-tangere, I. glandulifera and I. parviflora are likely to reflect the frost sensitivity of the species. In the highly frost-sensitive I. parviflora differentiation was found both in germination and frost resistance of individual populations. In I. glandulifera the differences among populations in frost sensitivity depended on temperature at the seed source and corresponded to the pattern of emergence of seedlings in the garden. In the native I. noli-tangere, the differences among populations in the time of germination depended on temperature at the seed-source locality. Since local adaptations were indicated both in native and invasive species studied, they are unlikely to provide the invasive Impatiens species with an advantage against the native congener, at least in terms of the traits investigated. [Copyright &y& Elsevier]

Invasive plants are typically managed using top-down control techniques that focus on the removal of the target organism. Bottom-up control limits the resources available to the undesired species by manipulating disturbance, competition, and successional processes, and thus may prevent reinvasion. Tamarisk species ( Tamarix sp.) have invaded riparian areas throughout western North America, resulting in expansive control efforts. A companion study has shown that a native competitor, Box elder ( Acer negundo), is capable of outcompeting and killing established Tamarisk through light interception in canyons of Dinosaur National Monument (DNM), Colorado. The goal of this study was to determine the feasibility of using Box elder as a bottom-up control agent by (1) determining the distributional overlap of the two species in DNM; (2) determining if Tamarisk facilitates Box elder establishment; and (3) analyzing Box elder seedling survival across a range of physical gradients. The distribution of Tamarisk and Box elder overlapped considerably throughout the study area. Box elder seedlings were planted under Tamarisk canopies or areas with the canopy removed. Survival was significantly higher under Tamarisk canopies, indicating that Tamarisk facilitates Box elder seedling survival. Box elder seedling survival was tested across soil texture, litter depth, groundwater depth, and shade intensities indicative of conditions found in the canyons of DNM, and survival was high for all treatments. The manipulation of competitive and successional processes through the promotion of Box elder and other native tree establishment is suggested as a means of bottom-up Tamarisk control to complement traditional control techniques. [ABSTRACT FROM AUTHOR]

Exotic species are an integral part of the plants used by many ethnic groups, but they usually receive little attention and have been considered alien to the ethnobotanical data. Here, we analyze the plants used by Thai Hmong refugees that are not native to their current habitats in Thailand. We attempt to understand the sources of this knowledge. Do people maintain the original traditional knowledge related to exotic species when they migrate to a new region, or does new knowledge originate from acculturation? We interviewed 16 specialist Hmong informants in Nan province, Thailand, about their traditional knowledge of 69 exotic species used. Acquisition of this knowledge has a long history; several species are the same as plants used by the Hmong in China and other countries, others are globally useful species which have become part of the pool of species that the Hmong have developed local knowledge about. However, migration also involves the integration of local knowledge from other cultures, and also adapts them to function in urban settings. This includes using closely related exotic taxa that replace some of the species they used in their original homelands. The migrants' traditional knowledge in their new habitats is more complicated and also involves the development of local knowledge that is entirely new. [ABSTRACT FROM AUTHOR]